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Review

The history, genotoxicity, and carcinogenicity of carbon-based fuels and their emissions: 1. Principles and background Larry D. Claxton * LDC Scientific Services, 6012 Brass Lantern Court, Raleigh, NC 27606, United States

A R T I C L E I N F O

A B S T R A C T

Article history: Received 7 May 2014 Received in revised form 17 July 2014 Accepted 20 July 2014 Available online xxx

As research expands the types of energy sources for the future, there is a need to understand the health impacts of fuels and their emissions and to understand what health-research data gaps exist so that in the future proper and informative research and decision-making can be done. In that regard, this series of papers will explore what is known about the history, carcinogenicity, and genotoxicity of fuels and their emission products and attempt to identify major data gaps and areas of interest for future research. The reviews will concentrate on petroleum-derived fuels and biofuels. Although the length of these papers may cause the reader to think otherwise, the coverage of published works is intended to be illustrative rather than exhaustive and is intended for a multidisciplinary audience. This series of papers is not a risk assessment; instead, it is an attempt to introduce the reader with the history and terminology needed when examining fuels and emissions for genotoxic effects. The purpose of this particular paper is to provide a background for the other papers (both within this series and within papers by others) and to establish some principles used in these reviews. In particular, this paper provides definitions, general histories relevant to the topic, an overview of the regulatory history, and appendices the author believes are useful to those interested in the fields associated with the toxicology of carbonaceous fuels and their emissions. ß 2014 Elsevier B.V. All rights reserved.

Keywords: Emissions Health Cancer Regulations Laws History

Contents 1.

2. 3.

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5. 6.

Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Need and history of fuels . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.1. Positive and negative environmental and health impacts of fuels and their emissions . . . . . . . . . . . . . . . . 1.2. Fuels and emissions – an international perspective. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Types of fuels . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Biofuels . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.1. Solid biofuels (wood, charcoal, peat, dung, etc.) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.1.1. Liquid biofuels (alcohols, fats, and oils) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.1.2. Fossil (mineral) fuels . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.2. Coal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.2.1. Petroleum. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.2.2. Other fuels . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.3. Combined fuels (also referred to as biofuels) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.4. Energy from fuels . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . The production of fuels: mechanisms and chemistry of energy production . . . . . . . . . . . . . . . . . . . . . . . . . 4.1. Relative amounts of energy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.2. Mutagenicity and carcinogenicity issues associated with fuels . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Review of regulations and public policies/practices that concern fuels and mutagenicity and/or carcinogenicity . Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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* Tel.: +1 919 839 8978. E-mail addresses: [email protected], [email protected], [email protected] http://dx.doi.org/10.1016/j.mrrev.2014.07.001 1383-5742/ß 2014 Elsevier B.V. All rights reserved.

Please cite this article in press as: L.D. Claxton, The history, genotoxicity, and carcinogenicity of carbon-based fuels and their emissions: 1. Principles and background, Mutat. Res.: Rev. Mutat. Res. (2014), http://dx.doi.org/10.1016/j.mrrev.2014.07.001

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1. Introduction With higher levels of energy production, society sees an increased standard of living that leads to improvements in general health and well-being. Indeed, the history of humanity can be seen through the improvement in energy sources. These improvements have increased the ease of living, longevity, population numbers, and the prosperity of humans [1]. In the past and currently, most of these energy sources have relied on chemical bonds of hydrocarbons that have saved solar energy in the form of hydrocarbon bonds within plants and animals. Because human society cannot survive without a continuous use and supply of energy, humans have exploited these hydrocarbon sources. Reddy et al. [2] in their review write, ‘‘The original source of energy for social activities was human energy – the energy of human muscle provided the mechanical power necessary at the dawn of civilization. Then came the control and use of fire from the combustion of wood, and with this, the ability to exploit chemical transformations brought about by heat energy, and thereby to cook food, heat dwellings, and extract metals (bronze and iron). The energy of flowing water and wind was also harnessed. The energy of draught animals began to play a role in agriculture, transport, and even industry. Finally, in rapid succession, human societies acquired control over coal, steam, oil, electricity, and gas. Thus from one perspective, history is the story of the control over energy sources for the benefit of society.’’ Because the history and toxicology of fuels (including their emission products) are intimately related, these reviews will explore the history, genotoxicity, and carcinogenicity of fuels and their emission products. The production of energy entails both quantifiable risk and measurable benefit. It is not surprising (perhaps a sign of our times) that some people put a disproportionate emphasis on either the hazard or the benefits. However, the calculation of potential risks and benefits by one analysis is often dissimilar from one group (or person) to another. The differences between the relative risks and benefits assigned by various analyses reflect differences in underlying assumptions, methodological approaches, and other factors (e.g., unconscious biases). Therefore, I admit that my career has created unconscious biases; however, I hope that the work of others will support my final conclusions. Perhaps a key benefit of these reviews will be that many people with their biases and interests will communicate concerning the hazards, risks, and benefits associated with fuels and their emission products and will attempt to reach a common ground in their understandings. Otherwise, decision makers will be forced to decide on the future of

energy alternatives, which may not please most and perhaps not provide the correct decisions. Decision makers chosen to lead our industries, our special-interest groups, and our local and national policies are facing extremely difficult issues. In the case of energy policy, these issues are highly technical and have many social, political, and moral implications. It is an almost impossible task for decision makers to filter through this quagmire of information and come to rational decisions when extremists and the media express their views. Yet, our decision makers are doing their best to reflect their constituents’ views. Therefore, scientists must provide unemotional views of the information and data surrounding a topic. I hope I have done that. Nearly 3000 different compounds, mostly organic, resulting from human activity have been identified in the atmosphere [3,4]. Table 1 provides a listing of the types of pollutants in environments. This complex mixture of pollutants can have impacts on health and the environment. The search for alternative fuels to reduce dependence on petroleum and emission of pollutants into the atmosphere has stimulated many scientific studies. Air quality in urban atmospheres depends on several related factors: primary pollutant’s emissions (emitted directly from sources to the atmosphere), secondary pollutants (resulting from the chemical reactions occurring in the environment and which involve some primary pollutants), and consumption (e.g., through geographical and meteorological factors) [3]. Primary pollutants can be associated with natural and anthropogenic sources. The pollutants emitted from sources may be in two physical states: adsorbed on/ in particulate matter (PM) or in a gas phase. In this context, the primary particles emitted by many natural and anthropogenic sources include volcanic eruptions, forest fires, fumes created by certain industrial activities, roadways, ‘‘marine spray,’’ and some biological materials [1,3]. Because (in recent decades) societies’ members have expressed concerns with the increase of anthropogenic pollution, there has been an initiation of programs aimed at improving air quality in cities around the world. One of the strategic actions to reduce the emission of pollutants in urban environments is the displacement of local industries from urban to non-urban areas [5]. This ‘‘dilution is the solution’’ strategy has not worked [6]. In addition, other solutions using carbonaceous fuels have not worked. The history of complex environmental mixtures (e.g., carbonaceous emissions from combustion processes) and genetic toxicology and carcinogenicity) are intertwined. Starting with Percival Pott in 1775 realizing that chimney soot is related to scrotal cancer [8] and in 1892 Butlin realizing that only scrotal skin and not other

Table 1 Types of pollutants observed in the atmospheric environment. Pollutant

Sources where pollutants mainly originate

Examples

CFC chemicals CH4 CO CO2 HNO3 N2O NOx O3 PAHs and PACs Pb (Lead) PM

Industry and residential sites Agriculture, traffic, and industry Traffic and industry Agriculture, traffic, and industry Traffic, industry, and residential sites Agriculture, industry, traffic, and residential sites Traffic, industry, and soils Traffic, industries, landfills, VOCs from paints and solvents, forests, gas stations, etc. Traffic, industry, residential sites, and agriculture Traffic and industry Traffic and industry

SOx

Traffic and industry

VOC

Chemical industry, traffic, storage of fuel and gasoline stations, car workshops, construction, and residential

Refrigeration, aerosols, propellants, expanded foams, and solvents. Production and consumption of energy, farming and livestock, landfills and wastewater In sources without after treatments for CO (e.g., catalytic converters) Use of fossil fuels, deforestation, and change of land use Combustion of wood and fossil fuels, the chemical composition of fertilizers, and microbes. Fertilizer use, production of acids, burning of biomass, and use of fossil fuels. Results from combustion and soil metabolism [7]. Secondary chemical reactions between some primary pollutants (such as NOx, VOCs, and/or CO) and sunlight. Occurs more when primary pollutants are emitted in the summer. Combustion of fuels. Leaded fuels and manufacturing processes with the use of certain raw materials Cement production, refineries, steel, paper pulp, chemical industry, construction work, agricultural practices, and combustion of fossil fuels. Vehicles using fuel with high sulfur content, chemical industry, pulp and paper processing, refineries and boilers using fuel with high sulfur content. Any combustion of fossil and other fuels, any industrial processes that use volatile portions of fuels, solvents.

Modeled after Miguel [5].

Please cite this article in press as: L.D. Claxton, The history, genotoxicity, and carcinogenicity of carbon-based fuels and their emissions: 1. Principles and background, Mutat. Res.: Rev. Mutat. Res. (2014), http://dx.doi.org/10.1016/j.mrrev.2014.07.001

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types of skin were involved [9], the dawning of environmental toxicology and genetic toxicology had occurred even though this was not realized at the time. Southam and Wilson [10] continued this effort on scrotal cancer by following the occupations of those showing this disease (out of 141 cases, the distribution was 69 mule spinners, 22 tar workers, 1 chimney sweep, 38 other occupations, and 11 patients not reporting an occupation). We then go back to Europe to find that, in the early months of 1900, investigators in The Netherlands (de Vries), Germany (Correns), and Austria (Tschermak-Sysenegg) rediscovered the 1866 work of Gregor Mendel [11,12]. With this rediscovery of Mendel’s classic article [12,13], a rapid development of the science of genetics began. The Dutch botanist Hugo de Vries [14,15] devised the word ‘‘mutation’’ to describe sudden hereditary changes in wild varieties of the plant evening primrose (Oenothera lamarckiana). Although these changes later were found to be due to other rare events, the term was preserved [16]. In the 1920s, mutation research was reaffirmed by Muller who showed unequivocally that radiation was a mutagen [17]. In 1941, Alexander Hollaender’s [18] contribution was noting that the action spectrum for UV-induced mutation of spores of ring-worm fungi resembled the absorption spectrum of nucleic acids and realizing that genes were made of nucleic acids at a time when most of his contemporaries were sure that they were made of proteins. They either explained away, were unaware, or ignored his discovery. Further mutation research was encouraged when Auerbach and Robson [19] in 1942 showed that the chemical warfare agent mustard gas was shown to be mutagenic (because of wartime censorship, results were not published until 1947). Muller [17], in his classic article on the induction of mutations by X-rays, suggested the possibility that mutations may well cause cancer. Now, science had a linkage between mutation, cancer, and chemicals. In 1953, Watson and Crick published the structure of DNA making a mystery of many years understandable [20–22]. It is amazing that the early pioneers accomplished so much without knowing the basic structure of genetic material. Now, science had a linkage between mutation, cancer, chemicals, and genetic material. During the First Erwin Bauer Memorial Lectures, Auerbach [23] stated in a paper (Chemical Mutagenesis in Animals) that ‘‘as more and more chemicals are used in therapeutics, food processing, and other industries, the testing of the substances for mutagenic ability will become a necessary protective measure.’’ During a 1962 conference, Goldstein expressed a concern for the health of man, not only for the present generation, but also for those yet unborn; and Muller expressed a concern that humans were being exposed to a great number of substances (such as food additives, drugs, narcotics, antibiotics, pesticides, cosmetics, contraceptives, air pollutants, and water pollutants) [11,24,25]. Now, there was a linkage between mutation, cancer, chemicals, DNA, and public health. In 1969, the establishment of the Environmental Mutagen Society demonstrated the strong linkage felt by pioneering members in genetic toxicology between mutagenesis and the environment [11,26]. At a conference entitled Evaluation of Genetic Risks of Environmental Chemicals, the proceedings of which were published [27], a working group chaired by Lars Ehrenberg, and consisting of Peter Brookes, Hermann Druckrey, Bengt Lagerlo¨f, Jack Litwin, and Gary Williams, addressed ‘‘The Relation of Cancer Induction and Genetic Damage.’’ It was Professor Druckrey [28] who suggested the following text: ‘‘In order to describe the components of chemical interaction with genetic material, the term genotoxic is proposed as a general expression to cover toxic, lethal and heritable effects to karyotic and extra-karyotic genetic material in germinal and somatic cells.’’. Because of its historic importance, this event was also mentioned within the cover legend of Cancer Research [29] that honored the careers of John H. Weisburger and Gary M. Williams. In 1977,

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Heinrich Malling said [30] that the overarching goal of the NIEHS Laboratory of Environmental Mutagenesis is the prevention of increased frequency of genetic disease in the human population and that ‘‘Some pollutants in the environment are neither mutagenic nor carcinogenic by themselves but can be converted by mammalian metabolism to highly reactive and genetically active metabolites.’’ He also stated ‘‘There are many harmful chemicals that we cannot avoid in the environment, such as SO2, nitrogen oxides (NOx), etc., some of which may be mutagenic. The human society must set limits to chemical exposure as was done for irradiation’’ [30]. Government agencies and others began to take a strong interest in genetic toxicology [31–38]. During the early period of governments being involved (approximately the 1960s and early 1970s), the primary concern for researchers and the government seem to be that genotoxic damage had the potential to cause heritable genetic alterations in the human germline. However, the milestone publications of Malling [39], Ames et al. [40,41], and McCann et al. [42] demonstrated a strong correlation between Salmonella mutagenicity and animal carcinogenicity and turned the emphasis to mutagenesis testing for predicting animal carcinogenicity. Later, a debate ensued as to whether the Salmonella mutagenicity assay was a predictor of carcinogenicity; however, the work of Zeiger and his colleagues seem to settle the conflicts. Zeiger [43] said, ‘‘It is concluded that the use of the Salmonella mutagenicity assay is warranted for the identification of carcinogens, but not for noncarcinogens. The proportion of carcinogens detected as mutagens is dependent on the specific classes of chemicals tested and on the rodent species used to define the carcinogens.’’ A publication by Claxton et al. [44] strengthened this observation by Zeiger when he examined correlations by chemical class. He concludes [44], ‘‘. . . validation values (sensitivity, specificity, etc.) vary with chemical class. Overall, this analysis demonstrates that when used and interpreted in a meaningful chemical class context, the Salmonella bioassay remains extremely useful in identifying potential animal carcinogens.’’ With the initial work at the USEPA by Huisingh (later Lewtas), Claxton, Nesnow, Waters, and their colleagues [45–61] and by others [62–87], examination of actual environmental contaminates (besides chimney soot) began. The USEPA held several international meetings on the genotoxicity of environmental complex mixtures and the manuscripts are found in books by Waters and his colleagues [88–92]. In summary, toxicology deals with the effect of agents on living systems, with the purpose of defining human health effects. It is an applied science that draws on a number of disciplines such as biochemistry, genetics, pharmacology, and the study of metabolism. Genetic toxicology, a subspecialty of toxicology, identifies and analyzes the action of agents with toxicity directed toward the hereditary components of biological systems (this includes both germline and somatic cells). Genotoxic substances usually interact with DNA (the universal target molecule that provides the scientific basis for the field of genetic toxicology including carcinogenicity [93]). Today, we also know that changes in DNA are associated with a number of other adverse human health effects. Wassom et al. [11] in their 2010 review stated ‘‘Some of the problems we face from chemicals are due to the formidable variety of chemical compounds to which humans may be exposed and their specificities depending on species, strains, sex, and cell stages on which they react and cause harm.’’ The Federal government (especially the USEPA) regulates toxic chemicals through following statutes: Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA) [94]; Toxic Substances Control Act (TSCA) [95]; the Resource Conservation and Recovery Act (RCRA) [96], the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA or Superfund) [97]; Clean Air Act (CAA) [98]; and the Clean Water Act (CWA) [99] and other laws (e.g., FDA

Please cite this article in press as: L.D. Claxton, The history, genotoxicity, and carcinogenicity of carbon-based fuels and their emissions: 1. Principles and background, Mutat. Res.: Rev. Mutat. Res. (2014), http://dx.doi.org/10.1016/j.mrrev.2014.07.001

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statutes). All congressional acts (Federal laws) adopt a standard that can generically be called unreasonable risk describing an undefined, nonzero level of risk determined on an ad hoc basis by balancing both health considerations and nonhealth concerns such as technology, feasibility, and cost. Because of the variety of chemicals in the environment and because these chemicals distribute to and behave differently in diverse species, tissues, and cells, much uncertainty is connected with genotoxicity testing. However, Applegate (in the Columbia Law Review) [33] says, ‘‘. . .not all uncertainty is ‘intractable’ and that most uncertainty results from the difficulty of learning about toxic substances with limited resources. Therefore, even if additional information will never eliminate uncertainty, it can usefully reduce uncertainty and improve agency decision making.’’ Therefore, it may be difficult but it is impossible to regulate toxic environmental substances. Life expectancy in the United States has grown to twice that of the 19th century, and environmental health (healthier food, cleaner water and air, better places to live) has been the greatest contributor [100]. Environmental health in the 19th century was practiced not only by physicians and scientists, but also, by engineers, lawyers, politicians, architects, and many others outside the health and science fields [100]. The primary tools for health improvement were infrastructure and sanitation [100]. For example, Frederick Law Olmsted (1822–1903) a landscape architect (who is better known as the designer of Central Park, Manhattan, New York City, New York; the Biltmore Estate grounds, Asheville, North Carolina; and many other well-known sites) served as Executive Secretary of the U.S. Sanitary Commission, a precursor to the Red Cross in Washington, D.C. He improved sanitation and tended to the wounded during the American Civil War, saving thousands of lives [100,101]. In the 1940s, the most serious aspects of air pollution were thought to be industrial emissions and the combustion of bituminous coal [102]. Because of the 1948 Donora, Pennsylvania, smog that killed 20 people and sickened 7000 and London, England’s ‘‘Great Smog of 1952’’ (where government reports estimated that 4000 people died prematurely and 100,000 more became ill and with recent research suggesting that fatalities were 12,000), little consideration was given to the motor vehicle as a source of pollution before the late 1960s [102]. In the late 1940s, although no one knew the chemical nature of the smoggy aerosol of Los Angeles, it was widely suspected that it had something to do with emissions of petroleum products. An industrial association of petroleum companies engaged the Stanford Research Institute to determine the chemical nature of smog [103]. Even after curtailing SO2 emissions (Los Angeles developed the nation’s cleanest air – from the standpoint of SO2 pollution – of any major city of the United States) smog continued to get worse. Arie Jan Haagen-Smit and Charles E. Bradley determined that the aerosol was composed of polymerized oxidation products of unsaturated hydrocarbons [103]. They showed that these unsaturated hydrocarbons were released from leaks of a butadiene plant, from gasoline storage tanks, from the gasoline tanks of automobiles, and were also present in the exhaust of automobiles. Further study showed that the formation of smog was even more complicated because it was not due to unsaturated hydrocarbons alone, but to their oxidation by ozone. The HaagenSmit [104] studies confirmed the details of the photochemical cycle by which primary pollutants were transformed into polymeric aerosols. In 1954 he wrote, ‘‘We have now received two warnings that our fresh air supply is limited. The first, a wave of eye irritation during the war years, was controlled within a year through corrective measures at a single plant. The second attack of severe air pollution has lasted eight years and involves hundreds of industries and millions of people. We shall overcome our immediate problem, but only constant vigilance and thorough planning will assure a permanent solution.’’ Over the past 50 years,

environmental science became highly specialized and fragmented. For example, the USEPA focused on legal and engineering strategies, health practitioners in local agencies concentrated on enforceable and fee-supported activities like food service inspection, and environmental health scientists increasingly emphasized the mechanisms of toxicity [100]. Today, public health leaders are asserting that the built environment profoundly influences health. Jackson [100] (former director of the Centers for Disease Control and Prevention National Center for Environmental Health) said in an editorial for Science (2007), ‘‘The focus [is on] sprawling communities that foster car dependency, inactivity, obesity, loneliness, fossil fuel and resource consumption, and environmental pollution.’’ Concern about the built environment’s effects on health demands that multidisciplinary (i.e., regulators, health practitioners, scientists, etc.) teams become involved in finding solutions to environmental health challenges. Disciplines long estranged from health issues (architects, planners, environmentalists, industrialists, builders, developers, etc.) should become engaged. As has been said, ‘‘The challenges of the 21st century will require leadership and collaboration. It worked in the 19th century; it can work today.’’ [100]. Because there is a link between the environment, public health, and fuel industries, there is a need to have a common knowledge about fuels and their emissions. With this understanding, decision makers can develop insight into existing and future problems (challenges). This series of papers [105–109] targets a multidisciplinary audience interested in the genotoxicity and carcinogenicity of carbon-based fuels and their emissions. See Table 2 for the areas reviewed. The main fossil fuels (crude oil or petroleum, natural gas, and coal) remain society’s major energy sources, and they are the feedstocks for a vast assortment of synthetic materials and products. The products range from gasoline and diesel fuels to plastics and pharmaceuticals [110]. In addition, in order to produce usable energy for many life-sustaining, vocational, and avocational purposes, humans place a great emphasis on converting one form of energy into another. By producing usable energy, people are able to cook, travel, perform work, enjoy recreation, wage war, and heal the sick and many other things (Table 3). Fuel is the material that is altered (e.g., burned or combusted) to obtain energy and to heat or to move an object. However, the processes associated with recovering and making fuels available for use and the using of fuels many times release toxic substances into the environment. These unwanted toxicants are associated with fuel spills, the refining of fuels, and the combustion of fuels. Global health is everyone’s concern in today’s world [112,113]. In many countries, chronic diseases (excluding infectious diseases) are the leading cause of adult mortality [114–116]. Therefore, we have an urgent need to understand, monitor, prevent, and control chronic diseases, especially cancer. In 2008, of the estimated 57 million global deaths, 36 million (63%) were due to noncommunicable diseases (NCDs) and 7.6 million (21% of the NCDs) were cancer deaths [117–119]. Projections are that by 2030 annual cancer deaths will increase to 13 million. The largest contributors to NCD deaths in 2008 were cardiovascular disease (48%), cancers (21%), and chronic respiratory diseases (12%) [117]. In the United States, 25% of all deaths are due to cancer [120]. The majority of all cancer deaths occur in low- and middle-income countries with the majority of these cancers being lung, breast, colorectal, stomach and liver cancers [121]. The type of cancer seen is obviously due to the types of prevailing risks. For example in subSaharan Africa, the leading cause of cancer death to women is cervical cancer because there is a high prevalence of human papillomas virus infection. The leading causes of cancer deaths in high-income countries are lung cancer for men and breast cancer for women [117]. As cultures add modern conveniences and health care, infectious diseases are declining and NCDs are increasing

Please cite this article in press as: L.D. Claxton, The history, genotoxicity, and carcinogenicity of carbon-based fuels and their emissions: 1. Principles and background, Mutat. Res.: Rev. Mutat. Res. (2014), http://dx.doi.org/10.1016/j.mrrev.2014.07.001

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Table 2 Categories of fuels and oils plus the paper (part) in which they are reviewed. Oil category

Examples

See part(s)a

Crude oil; heavy oil Light fuel Light oil

Crude oil, heavy fuel, No. 6 fuel, bunker, residual oil. Diesel fuel, No. 2 fuel, naphtha. Mineral oil, thermal oil, transmission oil, insulating oil, quench oil, heat transfer oil, light cycle oil, light oil, hydraulic oil, cutting oil, emulsion oil, spray oil, carbolic oil, gas oil, lean oil, clarified oil, produced oil, process oil. IFO, No. 3 fuel, No. 4 fuel. Gasoline, jet fuel, No. 1 fuel oil, crude condensate. Spindle oil, lube oil, gear oil, machine oil, compressor oil, crankcase oil, motor oil, cycle oil. Tar, asphalt, asphalt emulsion, creosote, and tack oil. Tallow, sperm oil, lard, animal fat, vegetable oil, soybean oil, seal oil, corn oil, canola oil, safflower oil, peanut oil, palm oil, fish oil, croton oil, coconut oil, cottonseed oil, tung oil, linseed oil, tanner oil, pine oil, and castor oil. Wood, charcoal, peat, dung. Coal, coke. Electricity (from fossil fuels), synthetic oil, dusting oil, road oil, resin oil, hot oil, wax, paraffin, nuclear, hydroelectric, geothermal, solar, tide, wind, waste.

1, 2, 3, and 5 1, 3, and 5 Not covered

Intermediate fuel oil Volatile distillate Waste oil; lubricating oil Asphalt/tar Animal fat and vegetable oil

Renewable solid fuels Solid fossil fuels Other oils and sources of energy

a

Not covered 1, 3, and 5 Crankcase and motor oils–3 and 5 Not covered 1, 4, and 5

1, 2, 4, and 5 1, 2, and 5 Synthetic fuels and electricity – 4 and 5

Part 1 is this paper, Part 2 is[106], Part 3 is [107], Part 4 is [108], and Part 5 is [109].

[117]. Choi et al. [122] summarize this occurrence in the following manner, ‘‘Put simply, human progress and technological advance have brought about a global epidemic of ‘diseases of comfort’. In spite of the progress being made, many countries lack the expertise and resources to conduct the needed disease and toxic sources surveillance and the actions that would prevent and control exposure to toxic substances.’’ Therefore, more advanced nations and international organizations will be asked for advice. In February 2001, a group of over 200 scientists, engineers, decision makers, and educators met together in North Carolina to review challenges in air-quality science, policy, and education. In this conference entitled ‘‘Future Directions in Air Quality Research: Ecological, Atmospheric, Regulatory/Policy, and Educational Issues,’’ four keynote speakers provided some of the salient points of the meeting. Ginsburg and Cowling [123] provided a summary

of this meeting. First, Dr. Daniel Albritton provided broad perspectives including ‘‘Recent experience has demonstrated conclusively that no one organization in any nation will have the necessary human talents, financial and other resources, and the vision with which to characterize adequately the air-quality issues of the future.’’ Dr. William Chameides noted, ‘‘Air pollution is linked to the natural chemical cycles of the earth and is best understood through the ‘one atmosphere’ [concept] . . . Ultimately, we care about the trace chemical constituents of the atmosphere because of their effects on public health and the productivity and stability of crop, forest, and natural ecosystems.’’ Dr. Norman Christensen, talking about educating the public and other scientists said that there are three important questions to be asked when we are educating others: What are the problems? What are we teaching? Who are we educating? He pointed out that

Table 3 Examples of the positive and negative health effects associated with the use of energy sources. Category affected

Positive effects (examples)

Negative effects (examples)

Air, outdoor

Production of pollution controls; usually not as concentrated as indoor air. Better environmental controls (e.g., for temperature, lighting, cooking); Filtering of outdoor air is possible. Food production (e.g., increased abundance, fertilizers, better transportation, improved irrigation, improved processing); Food refrigeration (improved preservation, reduced contamination); Better distribution. Disinfection of products; Increased distribution of health care products and services; Increased/improved production of health care products. Shielded from daily or seasonal environmental constraints (e.g., darkness, extreme temperatures, rainfall, or wind); Improved/increased transportation;

Pollution (ozone, NOx, particulates)

Air, indoor

Food

Health systems

Personal life styles

Soil

Better communication technologies; Increased access to personal products Fertilizers, Better tilling and crop harvesting.

Water, drinking Water, general

Increased/improved water disinfection Increased supply, Decreased exposure to disease vectors

Pollution (from heating, cooking, personal habits, etc.).

Contaminated with fertilizers, fuels, etc.

Unanticipated negative health effects of commercial products

Air and water pollution; Unanticipated negative health effects of personal products (e.g., tobacco combustion)

Fertilizer accumulation; Decreased nutrient levels due to increased irrigation and farming techniques; Contamination from spills and emissions. Some disinfection by-products are toxic Pollution due to spills and emissions

Source: [111].

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decision makers and the public at large have a limited understanding of why changes in the chemical and physical behavior of the atmosphere are important. Communication about these matters is challenging because of their complicated and multifaceted nature makes understanding the issues and setting priorities overwhelming. Dr. John D. Bachmann stated, ‘‘The current state of our air-quality environment—cleaner air, stronger economy, new tailored rules to ensure that this continues—has been greatly influenced by scientific contributions.’’ The four major keynote addresses presented at this conference inspired participants to provide many other observations and recommendations [123]. Concurring with these observations, I realize that it is: (1) beyond the talents of any one scientist, especially me, to provide information about all there is needed to know about pollution that can come from the use of fossil fuels, (2) not possible to identify all the trace constituents that come from fossil fuel use and their genotoxicity, (3) not possible for me to answer all the questions that readers may have, and (4) not possible to give credit to each of the thousands of scientists that have explored aspects of pollution caused by the use of fossil fuels. However, it is my wish that I can provide the basic understanding needed to do research in this field and direct the reader to the literature needed. Today, decision makers are largely concerned about the environmental impact of emissions of sulfur dioxide (SO2), nitrogen oxide (NO), and carbon dioxide (CO2). Globally, decision makers concentrate on the risk of global warming, which is linked to CO2 emissions from the burning of fossil fuels. In Europe, 60% of SO2 emissions and 30% of NO emissions come from electricity generation. Therefore, an energy charter to be adopted by all European countries, including the USSR, emphasizes environmental protection as one of its objectives [124]. Because the cost of fossil fuels is expected to increase, and the availability of fossil fuels is expected to decrease, society has an increasing interest in renewable alternative fuels. Key within these renewable fuels, are the ones that are derived from biomass. Photosynthesis is the means by which vegetable species use solar energy to create sugars from CO2 and water. This energy is subsequently stored in the form of glucose or starch molecules, oleaginous, cellulose, and lignocellulose. There are at least four reasons that renewable plant life is an attractive feedstock for fuels. First, it is a renewable resource. Second, biomass combustion generally releases a very low amount of sulfur. Third, carbon is theoretically recycled in a biological process in which carbon is released and taken up in equal amounts resulting with no net releases of CO2. Fourth, biomass usage may result in significant economic potential (provided that fossil fuel prices increase, quite substantially) [125]. Cadenas et al. [125] divided types of biomass fuels into the following four broad categories: (1) Waste – organic, urban, or industrial wastes; (2) agricultural residues – e.g., manure, straw, bagasse, and forestry waste; (3) uncultivated vegetation – e.g., trees, shrubs, and bracken, and (4) energy plantations – planted energy crops put into production for the purpose of producing plants as a fuel source. In categories (3) and (4), land may be diverted from other useful purposes. Critical to future transportation, industrial, urban, and residential planning is an understanding of the toxicology of fuels and emissions from those fuels. Transportation has fundamental roles in the lives of societies and individuals [126]. Included in these roles according to Krzyzanowski et al. [126] are: how people interact, work, play, organize production, develop cities, and get access to services, amenities and goods. In societies that rely heavily and increasingly on private motorized transport, vehicles are expected to become safer, more luxurious and powerful, and to be driven more frequently. These expectations often do not examine the ensuing consequences: increased fuel consumption, greater emissions of air pollutants, and greater exposure of people

to hazardous pollution that causes serious health problems. As needs evolve in the 21st century, society will ask ‘‘What fuels will power our vehicles, our factories, our businesses, and our homes?’’ Although many factors (e.g., availability, state of technology, political and economic influences, public opinion, etc.) will influence the answers to this question, one primary consideration should be the potential health consequences and benefits. As an aid in understanding the public health issues, this series of papers review what is known and not known about the carcinogenicity and genotoxicity of (1) of various carbon-based fuels, and (2) of the emissions from different fuels consumed by differing sources. These reviews do not address nuclear power or other energy producers that use non-carbon based fuels; therefore, the reader is directed to a National Research Council report [127]. When studying fuels and their emissions, several questions usually arise: (1) Are the emissions mutagenic and/or carcinogenic? (2) Do any process stream materials and fugitive emissions products produce negative health effects? (3) What compounds or classes of compounds contribute to the mutagenic activity and potential carcinogenicity? (4) How is mutagenic activity altered by pollution control devices and other after-treatments? Most studies generally focus on aromatic compounds in the production process and combustion products; however, researchers usually find that other types of chemicals also are toxic. This series of papers [105–109] is not a risk assessment. Instead, it is an attempt (1) to introduce environmental toxicologists and others with the terminology and history they need when examining fuels and emissions for toxic effects and (2) to document what is known about the carcinogenicity and mutagenicity of fuels and their emission products. More importantly, it is an attempt to understand what needs further scientific investigation. The purpose of this particular paper is to provide a background for the other papers (both within this series and within papers by others) and to establish some principles upon which the author relies in these reviews. Since the topic (the mutagenicity and carcinogenicity of fuels and their emissions) is designed for a multidisciplinary audience, some portions may be somewhat elementary for some readers; but, I hope that this series will fill needed gaps of understanding. Table 2 gives the commonly accepted categories of fuels and oils plus the paper in this series in which they are reviewed. Review articles were heavily relied upon (rather than individual research articles, unless otherwise indicated) for highly documented areas of research; therefore, readers should refer to these reviews for more detail. The coverage of published work is intended to be illustrative rather than exhaustive although the length of these papers may cause the reader to think otherwise. Within sections of these five papers, I have taken primarily a historical viewpoint (referring to papers in a primarily chronological fashion). There was not a heavy reliance on quantitative data because fuel and emission chemistry and associated toxicology have changed quantitatively with time. For example, gasoline fuels have reduced or eliminated lead as an additive, and many diesel engines have reduced the amount of aromatic compounds exhausted. Although the economic benefits from modernization, industrialization, and technology transfer seem attractive to many including decision makers, little attention usually is paid to the potential negative impact of any related actions that may occur. The impacts include air pollution, soil contamination, discharges that find their way to surface, coastal and ground water resources, and drinking water. These problems have long-lasting adverse effects. Therefore, some have pointed out that the success of modernization and industrialization needs to be carefully evaluated on the bases of economic benefits and associated risks with a major area of concern being environmental health [126,128].

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1.1. Need and history of fuels In prehistoric societies, humans learned to use available fuels as a source of heat and a means to cook, and they also learned to smoke and dry their foods for long-term storage [129]. Heizer [130] says, ‘‘The world distribution of tales accounting for the origin or possession of fire indicates that its appreciation in human consciousness may be one of the oldest intellectual ideas now identifiable . . . we are quite in the dark as to whether these early fire-users took advantage of natural fire or had learned to generate fire by the means of tools.’’ Even so, we do know that for the majority of human history that fuels derived from plants and animal fat were the only ones available for human use [130]. The main fuel the world over and through time has undoubtedly been wood. One alternative to wood fuel is coal, known to have been employed in late prehistoric times by the Hopi for household heating and the firing of pottery [130]. The Hopi abandoned coal as fuel because of the Spanish conquest which led to the introduction of sheep dung (used for fires), steel tools (for the cutting of wood), and donkeys (for the transport of firewood). Coronado, in 1542, observed that the only fuel available to the Plains hunters encountered by him was buffalo dung [131]; and among the Marsh Dwellers of the Euphrates Delta, water buffalo are important not only for the milk they produced but also for their dung which was the main fuel available [132]. In the Heizer review [130], he noted that: (1) the peoples in arctic or sub-arctic environments substituted animal fats for wood, (2) Scythia was barren of firewood and that fat-laden animal bones were used for fuel, (3) the eastern Eskimos burned bones which had been rubbed with sea mammal blubber, and (4) the maritime Chukchi hunted whales for their edible blubber as well as for the oil which they poured on moss, peat, or whale bones, which they burned instead of wood. When bones were burned as a substitute for wood, it was actually the oil that was the flammable substance that burned. As long ago as 6000 years, charcoal was the preferred fuel for smelting copper. With the invention of the blast furnace around 1400 A.D., charcoal was used extensively throughout Europe for iron smelting [133]. Forest depletion led to a preference for a coal-based form of charcoal (coke) as an alternative fuel [133]. Exposure to indoor air pollution can be traced to prehistoric times when humans first moved to temperate climates. Cold weather made the construction of shelters and the use of fire indoors for cooking, warmth, and light necessary. However, this use of fire, resulted in exposure to high levels of pollution as evidenced by the soot found in prehistoric caves [134,135]. It has been estimated that approximately half the world’s population, and up to 90% of rural households in developing countries, still rely on biomass fuels where indoor pollution occurs because of the use of open fires or poorly functioning stoves. This leads to levels of air pollution levels that are among the highest ever measured [136]. In the early stages of the industrialized age, the primary sources of energy were wood, coal, and whale oil [129]. In the United States, the primary fuel was wood from the early 1600s until the late 1800s at which time coal surpassed the usage of wood [129]. In the middle of the twentieth century, petroleum and natural gas along with coal became the primary sources of energy [137]. As research expands the types of energy sources for the future, there is a need to understand the health impacts of fuels and their emissions and to understand what health-research data gaps exist so that proper and informative research and decision-making can be done. In that regard, these papers will explore what is known about the carcinogenicity and mutagenicity of fuels and their emission products and attempt to identify major data gaps and areas of interest for future research. While the reviews will supply an overview of many fuels, the reviews will concentrate on petroleum-derived fuels and biofuels. Today’s society is very

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different from earlier societies because of energy sources. The higher quality energy sources and technologies of today have initiated a chain of demographic and health outcomes by changing socioeconomic relationships and the products found in today’s society [111]. For example, the American Petroleum Institute (API) web site (http://www.api.org/classroom/tools/upload/LifeInOilandNaturalGas.pdf) states, ‘‘When you stop and think about it, it’s amazing how many things get their start from oil and natural gas.’’ The API points out that besides helping to provide the energy for manufacturing products that oil and natural gas are used in the product lines of fertilizers, medicines, PVC pipes, plastics, carbon fiber composites, fabrics, etc. [138]. However, it is beyond the scope of this series of papers to examine these products. Many [111,126,137,139] point out there are both positive and negative aspects associated with increased energy use (Table 3). Therefore, it is important to point out awareness of these issues. The categories of fuel use that are of most concern to today’s society are (1) industrial, (2) transportation, and (3) residential. Although the ranking of these use categories depends upon the nation under consideration, the two types of fuel of most interest are coal and petroleum. In less developed nations, other solid fuels (e.g., wood, dung, etc.) may be of interest. Another fuel category of high interest (but will not be discussed in this series of papers) is nuclear energy. The main uses of coal are electricity generation, cement manufacturing, steel production, and conversion to liquid fuels. In 2011, approximately 6.1 billion tons of hard coal were used worldwide and 1 billion tons of brown coal were used. Since 2000, global coal consumption has grown faster than any other fuel. Today, the five largest coal users – China, USA, India, Russia and Japan – account for 77% of the total global coal use [140]. Although the existence of crude oil (petroleum) was known by early man because of areas of natural seepage to the surface that formed tar pits, the uses of petroleum were not generally recognized. Natural asphalt deposits and oil seepages have been and are widespread in the Middle East (especially in northern Iraq, south-west Iran, the Syrian desert, and the Dead Sea area) [141]. Since the Neolithic period, bitumen was found useful in the waterproofing of containers (baskets, earthenware jars, storage pits). Later, bathrooms, palm roofs, mats, sarcophagi, coffins, and jars were sealed with bitumen. Reed and wood boats were also caulked with bitumen [141–143]. Since these products generally are not used as fuels, asphalts will not be reviewed in this series of papers. Edwin Drake drilled the first commercially successful oil well in 1859 in Titusville, Pennsylvania. He created an industry that would go on to make petroleum highly significant. See the review of Binet et al. [143] for more information. Petroleum exists within the earth in a number of forms. The form and quality of crude oil depends on the factors associated with its formation (i.e., hydrocarbon source, exposures, and the temperature and pressure of the reservoir). Although light crude oil is a thin liquid of a brown or brownishblue/green color, some heavy crude oils are black solid tar-like substances. The specific gravity of most crude oils ranges from 0.73 to 1.07. Therefore, physical properties and chemical compositions also vary widely. The distillation products of crude oil are usually grouped into three categories: light distillates (e.g., LPG, gasoline, and naphtha), middle distillates (kerosene, diesel), heavy distillates and residuum (e.g., heavy fuel oil, lubricating oils, wax, and asphalt). This classification is based on the way crude oil is distilled and separated into fractions called distillates and residuum. The yield of a typical barrel of crude oil is given in Table 4. Crude oil is not of much use before refining. For refiners, the two most important qualities of crude oil are viscosity (density) and sulfur content. By using simple distillation, light crude oils yield a higher proportion of the more valuable final petroleum products,

Please cite this article in press as: L.D. Claxton, The history, genotoxicity, and carcinogenicity of carbon-based fuels and their emissions: 1. Principles and background, Mutat. Res.: Rev. Mutat. Res. (2014), http://dx.doi.org/10.1016/j.mrrev.2014.07.001

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8 Table 4 Percentage of main products in U.S. refining of crude oil. Product

Range in % of initial crude oil

Weighted average (%)

Liquefied refinery gases Finished motor gasoline Finished aviation gasoline Kerosene-type jet fuel Kerosene Distillate fuel oil Residual fuel oil Naphtha for petrochemical feedstock use Other oils for petrochemical feedstock use Special naphtha Lubricants Waxes Petroleum coke Asphalt and road oil Still gas Miscellaneous products

3.9–4.3 44.2–46.1 0.1 9.1–9.7 0.1–0.3 25.4–28.9 3.4–4.2 1.0–1.4 0.7–1.3 0.2–0.3 1.0–1.2 0.1 5.2–5.5 2.4–3.2 4.3–4.5 0.4–0.5

4.08 45.38 0.10 9.35 0.15 27.10 3.90 1.25 0.88 0.23 1.10 0.10 5.32 2.68 4.40 0.47

EIA, Refinery Yield (percent): Area: U.S., Period: annual (available at: http:// www.eia.gov/dnav/pet/pet_pnp_pct_dc_nus_pct_a.htm), in EIA, 2012 (release date: 6/28/2012). Notes: Totals do not equal sum of components due to independent rounding. See the above reference for more information on this table.

such as gasoline. Heavy crude oils have much less of the light hydrocarbons and require much more severe refining processes known as coking and cracking. Sulfur is a naturally occurring element in crude oil. Crude oils with high sulfur content (generally undesirable) are referred to as sour crudes, and those with low content of sulfur content are referred to as sweet crudes. Heavy investments are needed to remove sulfur from crude oils. The type of crude oil, therefore, has a bearing on refining yields of different products [144]. Starting in the late 1880s, mobile sources (i.e., automobiles and trucks, farm equipment, ships, small engine machines, airplanes, and trains) provided a major impetus to expand the use of petroleum. During 1876, Otto invented the first four-stroke internal combustion engine, which he used to build a motorcycle. In the same year, Karl Benz patented the first carriage with a gasoline engine. Two years later, Benz developed a two-cycle spark ignition engine, which was followed by the development of a fourcycle engine. In 1886, the first modern oil tanker, the Gluckauf, was built for Germany by England. Rudolf Diesel’s development of the internal compression ignition engine (1892) further encouraged the demand for oil, as did the Duryea brothers building the first internal combustion vehicle in the United States (1895), and Henry Ford building his quadricycle (1896). Most of the major automotive manufacturers began manufacturing between 1900 and 1925 with the first Model T rolling off the Ford assembly line in 1908. However, some manufacturers did not begin until the midtwentieth century. Motorized flight began in 1903 (at Kitty Hawk, N.C.), when the Wright brothers achieved the first heavier-than-air flight. Beginning in 1906, gasoline stations opened for business across the United States, but dispensing was done mostly by buckets and funnels. In 1922, Thomas Midgley began the use of tetraethyl lead as an antiknock additive in gasoline. The first offshore oil well was drilled in 1947. Very important developments occurred during the twentieth-century that allowed the doubling of compression ratios and lower engine weights for both gasoline and diesel engines [129,142]. Other developments centered on chemical additives for fuels. These developments in mobile sources allowed many welcomed modern advantages. For example, food is produced and distributed on a larger scale, more rapid and increased distribution of healthcare services, and increased supply of manufactured products. Among advantages, in 1900, the automobile provided a

relief from New York City pollution by replacing the city’s 120,000 horses that required disposal of approximately 1.1  106 kg (2.4 million pounds) of manure every day [142]. Airborne pollution caused by the emissions from mobile sources was soon recognized [145–152]. In addition, leakage to water supplies became a health concern (e.g., from leaking underground storage tanks and the use of MTBE) [153–156]. Therefore, these same mobile sources have been the cause of air and water pollution, contaminated soils and marshlands, and public health problems. Until the 1970s during a time of relatively cheap and abundant energy, the Federal government played a limited role in formulating the national energy policy. The nation relied on the private sector to fulfill most of its energy needs. The following overview of energy policies and events was taken from reports of the United States Department of Energy (USDOE) (http://energy.gov/node/%20362173), the USEPA (http://www.epa.gov/history), and the Aspen Institute [157]. Before the 1970s, Americans expected private industry to establish production, distribution, marketing, and pricing policies. Government and the public generally thought in terms of particular fuels, technologies, and resources rather than ‘‘energy.’’ The Shippingport Atomic Power Station, the world’s first full-scale nuclear power plant, became operational on December 23, 1957. On November 9, 1965, the first major power blackout covered the northeast United States. On March 13, 1968, the Atlantic Richfield Company along with the Humble Oil and Refining Company announced the discovery of oil on the North Slope of Alaska at Prudhoe Bay. The Cuyahoga River in Ohio became so polluted that it caught on fire. The Cuyahoga River fire (June 29, 1969) helped to spur the creation of the federal Environmental Protection Agency and the Ohio Environmental Protection Agency. President Nixon signed on January 1, 1970, the bill that created the Council on Environmental Quality (CEQ). During September, 1970, electric power ‘‘brownouts’’ again hit the northeast United States during a heat wave. In the mid-1970s, the energy crisis and the need to save the environment hastened a series of government reorganizations as both the executive and legislative branches sought better ways to coordinate Federal health, energy, and environmental policies and programs. The First Earth Day (April 22, 1970) saw more than 20 million Americans participate in a large grassroots community service movement. The official formation of the USEPA occurred on December 2, 1970, as a result of President Richard Nixon’s ‘‘Reorganization Plan No. 3’’ issued in July 1970. The agency consolidated environmental research, monitoring, and enforcement activities into a single agency. USEPA’s mission was to protect human health by safeguarding the air we breathe, water we drink, and land on which we live. In the Clean Air Act of 1970 (CAA), Congress authorized the USEPA to set national air quality, auto emission, and anti-pollution standards. In a July 4, 1971 message to Congress, President Nixon called the breeder reactor the best hope for meeting the growing demand for economical clean energy. Vehicle Fuel Economy Testing was given to the USEPA on December 31, 1971. In 1972, The USEPA announced that all gasoline stations must carry ‘‘nonleaded’’ gasoline, but would delay setting standards until 1973. 1973 was the first year in which the catalytic converter was used to control pollution in order to help meet the reductions required under the Clean Air Act, and lead compounds were not permitted in gasolines to allow the use of catalytic converters. During October, 1973, the United States experienced fuel shortages when on October 6, 1973, the Yom Kippur War in the Middle East broke out and the Organization of Petroleum Exporting Countries (OPEC) declared an oil embargo which sparked the first ‘‘energy crisis’’ for the United States. This oil embargo triggered a spike in oil prices and scarcity of supply, and stimulated efforts for conservation and research into alternative energy sources. In 1975, Congress established fuel economy

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standards and tailpipe emission standards for cars. On August 4, 1977, President Carter signed the Department of Energy Organization Act. The Federal Energy Administration and Energy Research and Development Administration were abolished. During 1977, The U. S. Department of Energy (USDOE) was created. Then in 1985, The U.S. government canceled the USDOEs ‘‘synfuels’’ project due to low prices for gasoline and diesel fuels. In 1978, the ‘‘Love Canal Disaster’’ efforts uncovered pollution caused by buried leaking chemical containers [158]. The pollution was linked to serious health threats such as cancer and birth defects. President Carter declared an emergency and authorized the USEPA to help relocate about 700 families. This lead to Congress passing the Comprehensive Environmental Response, Compensation, and Liability Act, also called the Superfund Act, which authorized the USEPA to identify those responsible for the contamination of sites and to compel the responsible parties to clean up the sites. The ‘‘Three Mile Island Nuclear Accident’’ occurred March 28, 1979. This was a severe meltdown of the nuclear power plant near Harrisburg, Pennsylvania, and the meltdown raised awareness and provoked discussion about nuclear power safety. January 1, 1986 the USEPAs final standard for lead in gasoline went to 0.10 g per gallon. An interim standard of 0.50 g per leaded gallon had taken effect July 1, 1985. The Exxon Valdez Spill occurred on March 24, 1989 spilling 11 million gallons of crude oil into Alaska’s Prince William Sound. The spill spurred the adoption of the Pollution Prevention Act. January 29, 1996 marked the date for completion of a 25-year mission to completely remove lead from gasoline. Administrator Browner called it ‘‘one of the great environmental achievements of all time.’’ In 1999, President Bill Clinton announced tougher tailpipe emissions standards for cars, sport utility vehicles, minivans and trucks, requiring them to be 77–95 percent cleaner. The 2004 Clean Air Nonroad Diesel Rule (Reduced Emissions for Off-road Vehicles with Diesel Engines) proposed emission levels for construction, agricultural, and industrial dieselpowered equipment by more than 90 percent. The new rule (which targeted removing 99 percent of the sulfur in diesel fuel) resulted in dramatic reductions in soot from all diesel engines. Starting June 1, 2006, refiners and fuel importers were required to start providing Ultra Low Sulfur Diesel, which contains 97% less sulfur than the fuel used previously. This cleaner-burning fuel was expected to reduce air pollution from diesel engines by more than 90% which would amount to 2.6 million tons of NOx and over 100,000 tons of PM. The USEPA in 2008 made drastic cuts in PM and NOx emissions from locomotive and marine diesel engines. When fully implemented, these new standards would reduce PM by 90 percent or 27,000 tons and reduce NOx emissions by 80 percent or nearly 800,000 tons. On April 20, 2010, the BP-operated Deepwater Horizon oil rig in the Gulf of Mexico exploded and killed eleven workers. The resulting release was the largest oil spill in American history. Recognizing that the extraordinarily high exposures to toxic indoor smoke from indoor fires and inefficient cookstoves leads to nearly two million deaths each year, primarily in young children and women, on September 21, 2010, the USEPA committed to contributing millions to the Global Alliance for Clean Cookstoves. 1.2. Positive and negative environmental and health impacts of fuels and their emissions It is interesting to note that complex mixtures were the first substances to be implicated in cancer. In 1760, John Hill [159] (as an add-on to a poem published by Baynard) noted that nasal cancer occurred in some people who used snuff excessively. However, Percival Pott [8] is generally the first investigator in modern medicine to be associated with a particular cancer (cancer of the scrotum) with the environmental exposures of a profession

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(chimney sweeping). In his 1892 review of Pott’s work, Henry T. Butlin [9] confirms this association and says ‘‘Seeing, then, the comparative frequency with which cancer attacks the scrotum in chimney-sweeps, the inference is strong that there is something in the trade of a sweep which modifies the skin of the scrotum to such an extent as to render it liable to the occurrence of cancer. Nay, more, the modification is so decided and of such a kind that the integument of the scrotum is not merely predisposed to the occurrence of cancer, but is more predisposed to it than the integument of any other part of the body.’’ Therefore, early evidence suggested that environmental contacts can be associated with cancer and that some tissues or cells may be more easily induced by these environmental substances than other tissues or cells. Epidemiological evidence, also, has been important in detecting carcinogenic substances. Rehn (1895) reported an increased incidence of bladder cancer in aniline dye workers in Germany [160]. In 1859, Bouisson described oral cancer in tobacco smokers [160]. Experimental carcinogenesis was pioneered and the first chemical induction of cancer in laboratory animals was achieved by Yamagiwa and Ichikawa [161,162] by painting coal tar (the products of the distillation of coal) on the ears of rabbits every 2–3 days for more than a year. Their experiments succeeded in producing multiple squamous cell carcinomas in the painted areas [161,162]. Specimens from their experiments are still on display in the museum of the Faculty of Medicine, University of Tokyo. Bloch and Dreifuss in 1921 were the first to explore the chemical basis of coal tar carcinogenicity, but they could not identify the individual compounds responsible [160]. Although Cook et al. [163] showed that a large number of known constituents of coal tars were negative for carcinogenicity, they also demonstrated that ‘‘1:2benzpyrene’’ (BaP) gave malignant tumors [164] of the skin of mice just as rapidly as the material isolated from pitch. Thus, in a preliminary series of 10 mice painted with the synthetic material, 5 died very early and the remaining 5 all developed tumors (4 epitheliomas and 1 papilloma); in one mouse there was a glandular metastasis in the right axilla. These and subsequent series of experiments on mice, for which we are indebted to Professor E. L. Kennaway and which will be described elsewhere, suggested that BaP produces tumors in about half the time required by 1:2:5:6dibenzanthracene, so that ‘‘1:2-benzpyrene is the most active carcinogenic compound yet known’’ [163]. Tumors in animals were seen in 1922 when Passey [165] obtained malignant skin tumors in mice with ether extracts of household chimney coal soot. In 1949, Goulden and Tipler [166] identified 3:4-benzpyrene (benzo(a)pyrene or BaP) as one of its components. Using the same method, Waller [167] in 1952 detected BaP in samples of smoke drawn from the air of eight different towns and in the other soot deposits [168]. In 1952, Waller [167] stated, ‘‘Whilst the above results [of his research] indicate that much of the benzpyrene found in the air is contained in coal smoke, it may not come exclusively from this source. Benzpyrene is found in some mineral oils, and hence one must consider the possible effect of internal combustion engines. A blue haze of extremely fine sooty particles is sometimes emitted from the exhausts of petrol engines, and occasionally a cloud of black smoke from diesel engines. A small deposit of soot often builds up near the end of exhaust pipes, and this is probably similar to the material dispersed into the atmosphere. Samples taken from a motor cycle, two cars, and two diesel compressors have all shown the presence of benzpyrene.’’ To summarize his research paper Waller [167] said, ‘‘Benzpyrene has been detected in samples of smoke drawn from the air at eight different towns in England. The concentration rises sharply during the winter, and there is a tendency for the mean annual values to increase with the size of the town. A large part seems to come from domestic fires, but it has

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been detected also in the exhaust from internal combustion engines.’’ The inhalation of mixtures of gases, vapors, aerosols, and particles can cause a wide range of adverse health effects, ranging from simple irritation to systemic diseases [169–171]. Considering that there are extremely large numbers of chemicals in most environmental mixtures, identifying the toxic chemicals by in vivo testing is unachievable from both economical and practical perspectives [172]. Regulatory agencies are reluctant about replacing whole-animal methods with in vitro techniques. However, studies demonstrate that in vitro methods may have significant potential for assessing the toxicity of environmental contaminants [172–178]. The first toxicology studies in the United States were those reported in 1927 when the LD50 test was introduced by Trevan [179]. When examining test systems that are not reliant on whole animal tests, the initiative to use in vitro techniques probably began with Russell and Burch [172,180–182]. Their thoughts can best be summarized by the ‘‘three Rs’’ they gave in their book The Principles of Humane Experimental Techniques [183] which are:  Reduction in the number of test animals,  Refinement of test protocols in order to minimize suffering of test animals, and  Replacement of current animal tests with appropriate in vitro tests. In addition, as in vitro test methods began to be developed, other advantages of in vitro test methods, especially in genetic toxicology, became obvious [174,184]. Included were advantages like lower costs, fewer time constraints, additional mechanistic information, and predictive tools for chronic effects [36,174, 182,184–187]. 2. Fuels and emissions – an international perspective Pollution and health effects of fuel-based pollution are a worldwide problem. For example, in 2007 it was reported that because China puts a coal-powered plant into operation roughly every four days, China’s emissions are ‘‘undoubtedly soaring’’ [188]. However, in 2003, China’s per capita emissions were 3.2 tons of CO2/person whereas the United States emitted 20 tons/person [188]. From 1975 to 2005, the world population grew from 4.1 billion to 6.7 billion, approximately 64%, and is expected to increase to 7.9 billion by 2025 [189]. In the period 1975 to 2025, the fraction of people living in urban settings will have increased

from 37% to 57%. In 1975 there were three urban areas with over 10 million inhabitants, in 2005 there were 18, and in 2025 the United Nation report estimates that there will be 27 such urban areas [189]. See Table 5 to examine these growth figures. Fenger [191] says that urban areas pass through three stages of pollution: a build-up stage (when pollution increases), a maximum stage, and an abatement-strategy stage (when pollution is reduced). Therefore, for some types of pollution (e.g., soot and SO2) modern western world air pollution is decreasing while air pollution in emerging urban areas in other parts of the world is increasing. However, many cities in Eastern Europe remain in the second stage with highly polluted urban areas, and many have not yet dealt with the problems that come from atmospheric photochemical reactions that produce additional pollutants [191]. In addition, pollution generally knows no boundaries. The waters of rivers, lakes, and oceans often touch the shores of multiple countries. Urban air pollution is a significant contributor to transboundary pollution [191–193]. Although the rising number of private cars is an emerging problem in many parts of the globe (including underdeveloped regions), fuel is still used in many different ways in different regions. For example, while many westerners cook using electricity which itself causes no indoor air pollution, indoor use of coal and wood for cooking and heating is common in many parts of Asia and Africa [191]. In underdeveloped and less developed countries, critical information on the level of exposure to environmental hazardous substances and the association of these substances with health effects is lacking. In Egypt, which is on the cusp of developed and lesser developed countries, exposure to chemical environmental genotoxicants (e.g., automobile exhaust, pesticides, metals and cytotoxic drugs) and to lifestyle factors (e.g., consumption of tobacco products) have been linked to biological effects including an increased risk for cancer. For example, 83% of the industrial sites are located in the vicinity of Cairo and Alexandria. In one industrial suburb of Cairo, 29% of school children suffer from lung diseases compared to 9% in rural areas of Egypt [128]. Because 45% of Egypt’s motor vehicles are found in Cairo and 13% in Alexandria, they see motor vehicles as important sources of air pollution in cities [128]. Therefore, Egypt and less developed countries provide unique opportunities for examining public health problems associated with exposure to environmental mutagens and carcinogens [128]. Research during past decades has indicated consistently the adverse effects of outdoor air pollution on human health, and the evidence has pointed to air pollution from mobile sources as an important contributor to these effects [194]. Roadway

Table 5 Growth of urban populations: summary of data given by the United Nations. Size of Urban settlement (i.e., range of number of Inhabitants)

Population by year

1975

2007

2025

World

Urban area totals 10 million or more 500,000–10 million Fewer than 500,000

1519 53 601 864

3294 286 2032 1712

4584 447 1785 2354

100.0 3.5 39.6 56.9

100.0 8.7 39.3 52.0

100.0 9.7 39.0 51.3

More developed regions

Urban area totals 10 million or more 500,000–10 million Fewer than 500,000

702 42 258 401

910 89 334 487

995 103 362 531

100.0 6.1 36.9 57.1

100.0 9.8 36.7 53.5

100.0 10.3 36.3 53.4

Less developed regions

Urban area totals 10 million or more 500,000–10 million Fewer than 500,000

817 11 344 463

2384 197 962 1 225

3590 344 1423 1 822

100.0 1.3 42.1 56.6

100.0 8.3 40.3 51.4

100.0 9.6 39.7 50.8

Region

1975

2007

Percent of population by year 2025

Taken from data given in Table I.5., Population Distribution of the World and Development Groups, by Area of Residence and Size Class of Urban Settlement, 1975, 2007, and 2025 [190].

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transportation will remain a significant contributor to air pollution in most cities. For example, because catalytic converters are not as effective in the initial minutes of engine operation and many urban trips cover distances of less than 3–4 miles (5–6.5 km), the average emission per distance driven is very high in urban areas. In addition, poorly maintained vehicles are responsible for a large share of pollutant emissions. Tailpipe emissions of PM 91 N/A to turbine engines N/A to turbine engines

77,600 147,894

64,600 123,143

34.8 37.6 35.5 9.3 25.3 25.5–28.7 17.9 34.3

108–110 123

Source: U.S. Energy Information Administration, various tables. Notes: ? = not sure of value.

Alcohols: Alcohols contain oxygen in addition to carbon and hydrogen. Ethanol is one example of an alcohol that can be used as a fuel. In effect, alcohol is a hydrocarbon that has already partially reacted with oxygen:

2 C2 H6 þ O2 ! 2 C2 H5 OH The main purpose of any engine is to convert the stored energy of a fuel into mechanical work so that a vehicle or other system can be powered. Flynn [244] says, ‘‘the engine represents a vessel for harboring the chemical processes that do this important job.’’ Therefore, the chemistry of fuel oxidation determines the conversion process by which an engine converts a fuel into usable energy. 4.2. Relative amounts of energy Fuels obviously are not all the same. Not only do they differ in their source and processing, but fuels differ in the amount of energy per volume, per weight, and by other measures. Table 9 compares examples of various fuels and their energy contents using different measures. Wall [245] repeats a story in which accounting is compared ‘‘with a cashier counting his cash only by the number of coins or notes, and neglecting their value.’’ He says. ‘‘This comparison has a striking similarity with what is happening in the energy description . . .’’ area. In other words, it is similar to counting a ‘‘hundred dollar bill’’ the same as a ‘‘one dollar bill’’ because there is no belief that value matters. This view of energy contents hampers decision makers and researchers from making proper decisions. Therefore, emission measurements (e.g., Salmonella revertants) from a fuel may be similar on a weight basis (e.g., per kilogram), but be dissimilar when compared on distance traveled (e.g., per kilometer). In order to examine emissions on an analogous basis, many comparisons are made on an energy expended basis (e.g., per megajoule of energy). 5. Mutagenicity and carcinogenicity issues associated with fuels Identifying mutagens and carcinogens in complex mixtures (e.g., in ground and surface waters, sediments, soils, air particles, exhausts of engines, and energy sources such as petroleum products) can have a high priority. Identification of individual genotoxicants is an aid in developing better emission controls, having better exposure data for epidemiology studies, designing higher levels of toxicity tests, understanding what makes a

particular complex mixture toxic, understanding the data on how environmental transformation can change the toxicity of a complex mixture, etc. This is obvious when one realizes that most hazard assessments of pollutants in air, soils, surface and ground waters, and sediments was and is based on preselected compounds for which there is an abundance of toxicity information (e.g., priority pollutants). It can be demonstrated, however, that the toxic effects of environmental mixtures are often caused by other, unknown or unexpected contaminants [246]. Included in the unknown or unexpected contaminants are industrial by-products, emissions, and environmental transformation products. Risk assessments of such complex mixtures based on previously evaluated pollutants and the modeling of toxicity using individual compound toxicity data, has been very useful; however, this approach can be meaningless if key contaminant toxicity is not known prior to the risk assessment [246]. Toxicity assessment using biological-toxicity tests is sometimes an established alternative for hazard assessment of complex environmental mixtures (especially in ecological areas of research and regulation). This approach provides an integrated assessment of the toxicity for the mixture of compounds affecting the applied test system. In such testing, prior knowledge of key toxicants is not necessary and any interactive toxicity among the components is included within the resulting data. However, such toxicity testing alone does not identify which compounds are causing the toxic effects. Therefore, it may be difficult to design risk reduction methods (e.g., remediation or emission controls) [246]. Researchers have shown that bioassay-directed fractionation (BDF), also known as effect-directed analysis (EDA), can be useful when applied to toxicant identification in air particles, soils, sediments, effluents, surface and ground water [247–250]. Reemtsma [251] reminds his readers that the concepts of BDF are not new, but that this concept is gaining more and more attention. Some studies using BDF were very successful, others were not. For example, extracts of selected xerographic toners and copies, found to be mutagenic in the Salmonella assay, were identified by BDF to contain nitropyrenes as impurities in a carbon black used as a toner colorant [85]. Changes in the manufacturing process resulted in a reduction of the nitropyrene content and reduced the mutagenicity of the toners [85]. When similar methods were applied to diesel emissions, it was shown that nitroaromatic compounds were also responsible for a portion of the genotoxic activity [250]. Austin et al. [247] showed that BDF methods were appropriate to compare the particle-bound organics from divergent sources. They used the Salmonella assay to examine the organic emissions from diesel particulate emissions, cigarette smoke condensate (CSC), coke oven emissions, and roofing tar

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samples. However, Reemtsma [251] said ‘‘Nevertheless, the process of toxicity-directed wastewater analysis is still judged too laborious to be widely applicable. Future method development may, thus, be directed toward automated extraction and fractionation procedures and miniaturized toxicity detection systems. The inclusion of biological test systems at the cellular or suborganismal level and directed to sub-lethal effects appears promising.’’ BDF has the potential to reduce the complexity of environmentally obtained complex mixtures to individual toxicants. Although identifying individual compounds may be ideal, much can be learned by identifying only the toxic classes of chemicals in a mixture. Various combinations of physicochemical fractionation procedures, and biological effects testing have been used [246]. In BDF, the following generalized procedure is done:  Initially, bioassays are used to determine what type(s) of toxic activity characterize the whole, testable mixture.  After a separation step the fractions are biotested for selection of active fractions for further investigation.  The active fractions again undergo a separation step.  This reiterative process (bioassay-separation) is repeated until highly toxic chemicals or groups of compounds are identified, or the sample quantity is too limited for further testing.  If possible, each active fraction of the mixture is reduced to a few individual compounds, and the fractions are used for chemical identification and quantification. Because many environmental toxicants are sorbed onto water or air PM, sediments, soils, or found in contaminated tissue, the first step of BDF and toxicant identification is the separation of the toxicants from the matrix by extraction. However, this step is selective, extracting some compounds and excluding others. The fractionation method used can be based on a number of physicochemical and chemical properties (expected of the toxicants) including polarity, molecular size, planarity, the presence of specific functional groups, and hydrophobicity [246]. The fractionation of the mixture itself can provide information about the fractionated compounds, which may be useful for identifying toxicants [246]. In BDF, the toxic potency of the fractions guides any further fractionation and chemical analysis. Obviously, the selection of the bioassays determines which types of toxicants are identified. Because time and sample availability are precious, proper selection of the bioassay(s) is critical. The major criteria for bioassay selection are the type of toxicants of interest (the ability to discriminate toxic from nontoxic fractions), rapidity (speed of throughput), a low volume requirement, reproducibility, sensitivity, and the ability to provide quantitative results [246]. Most mutagen/carcinogen identification studies have been based on the Salmonella mutagenicity assay [44,52,92,246,247,250,252–262]. Because of the sample amount available, most studies have limited Salmonella studies to one or two tester strains, most often TA98 and TA100 [246]. White [248] stated the paucity of knowledge about the behavior of genotoxic compounds in complex mixtures as a major problem in risk assessment of complex mixtures [246]. Environmental pollution (which is a subject of environmental, social, legal, and economic concern within many countries) has to be evaluated, regulated, and managed. Risk assessment not only is used to regulate substances but is used to manage environmental media and to support environmental management decisions. In other words, risk assessment is widely used as a means of assessing and managing impacts of toxic pollutants to human and ecosystem health. Although a proportion of pollution may be due to historical practices, modern practices also produce potential contaminants. Therefore, societies need a system for comparing and managing risks. Risk assessment methods give societies a critical portion of

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the tools needed. Energy sources are needed throughout the world. However, all energy sources either directly or indirectly cause pollution through emissions, accidental spills, and/or leakage (i.e., fugitive emissions). Risk assessment can be used to minimize risks to human health, property, watercourses, ecosystems, etc. Most pollution consists of highly complex mixtures of organic and inorganic constituents. The composition of polluting compounds varies substantially and depends upon the original makeup of the starting substance, how it is processed and used, and how it weathers. The phrase ‘‘how it weathers’’ refers to physical, chemical, and biological processes that further change a mixture’s availability, distribution, composition, and toxicity. Such interactions also include absorption, adsorption, biotransformation, hydrolysis, oxidation, photolysis, and volatilization. Performing a risk assessment for any environmental mixture brings several, hard-to-overcome problems. Although there are numerous approaches to risk assessment [36,115,153,236,263– 300], one useful method demonstrated in the 1980s with various emissions was the comparative potency method [264,290,301,302]. An estimation of the human lung cancer ‘‘unit risk’’ from automotive emissions was made using this approach [55,58,264,290,301,303– 307]. This method involved evaluating the tumorigenic and mutagenic potencies of the particulates from four diesel and one gasoline engine in relation to other combustion and pyrolysis products (coke oven, roofing tar, and cigarette smoke) for which there is good epidemiologic data and which are known to cause lung cancer in humans. The unit cancer risk is predicated using the linear nonthreshold extrapolation model and is the individual lifetime excess lung cancer risk from continuous exposure to 1 mg carcinogen per m3 inhaled air. The human lung cancer unit risks obtained from the epidemiologic data for coke oven workers, roofing tar applicators, and cigarette smokers were, respectively, 9.3  104, 3.6  104, and 2.2  106 per mg particulate organics per m3 air. The comparative potencies of these three materials measured in unit risk values were used to estimate the unit risk values of diesel and gasoline engine exhaust particulates from the data of an in vivo tumorigenicity bioassay and by results in in vitro genotoxicity assays. The in vivo tumorigenicity bioassay involved skin initiation and skin carcinogenicity in SENCAR mice. The in vitro bioassays originally used were the Salmonella mutagenicity assay, the L5178Y mouse lymphoma cell mutagenesis bioassay, and the sister chromatid exchange bioassay in Chinese hamster ovary cells. A high correlation existed between the in vitro and in vivo bioassays in their responses to particulate extracts. Using the mouse skin initiation assay, the relative potencies of the coke oven, roofing tar, and cigarette smoke emissions were within a factor of 2 of those determined using the epidemiologic data. Based on comparisons with three sources with epidemiologic data, the unit cancer risk for the particulates from one of the four diesels used averaged 4.4  104. The unit lung cancer risks for the other, motor-vehicle emissions were also determined using the comparative potency method. Using three in vitro bioassays, relative to the most potent diesel, the unit lung cancer risk per mg particulates per m3 for the automotive diesel and gasoline exhaust particulates ranged from 0.20  104 to 0.60  104; that for the heavy-duty diesel engine was 0.02  104. These unit risks combined with human population exposure estimations provide a basis for an estimation of human lung cancer risks for populations exposed to automotive emissions [289,290,301,302,308,309]. The term ‘‘comparative risk assessment’’ has been applied in a number of different ways [310,311]. Health considerations should not be given only to the emissions of the fuel but should be given in proportion to the Life-cycle Assessment of the fuel [312]. For example, Colvile [312] states that when estimating automotive emissions, 75% of the emissions are from exhaust combustion; however, 10% is associated with the car’s manufacture and 5% are associated with refining and

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transport of the fuel. Colvile et al. [312] also point out that while switching fuel sources may have some benefit that the trade-offs have to be considered. For example, the switching of trains and automobiles from petroleum fuels to electricity has a positive effect on urban pollution by transferring the pollution to a distant power source with different emissions. If this power source is a coal-fired power plant then the type of pollution is altered because many coal-fired power plants may emit SO2. Therefore, there is less concern over the combustors of the future (e.g., diesel engine, gasoline engine, electric engine, etc.) and more concern over which energy source (e.g., diesel fuel, gasoline fuel, coal, etc.) will power the engines of the future. In 1989, Bender et al. [313] reported on an occupational cohort mortality study that examined Minnesota’s highway maintenance workers (HMWs) employed between 1945 and 1984. Although the overall mortality was reduced, plausible increases in leukemia and urologic cancer mortalities were found. Leukemia mortality in HMWs with 30–39 years of work (SMR = 425; CI95% = 171–876) and urologic cancer mortality in HMWs with 40–49 year latency (SMR = 292; CI95% = 117–602) were significantly elevated. Since these men may have shared experiences other than just their work, the extent to which these findings are related to particular workplace exposures remains unknown. If related to work exposures, the sources of carcinogens are hard to determine because HMWs are exposed to a broad range of potentially toxic substances (e.g., asphalts and tars, benzene, diesel fuels and exhaust, and herbicides). Presently, there are no energy sources which can substitute for all liquid hydrocarbon fuels. This statement is both obvious and true because no other fuels: (1) are so readily abundant to use as a fuel, (2) are known to have such a high energy density, (3) store energy so efficiently and conveniently, (4) release their stored energy so readily (rapid oxidation/combustion), (5) have the existing infrastructure that petroleum fuels have, and (6) are so easily transported. Although these positive factors argue for the continued use of petroleum fuels, other factors argue that petroleum fuels contribute to: (1) environmental pollution, (2) an environment that is burdened by toxic substances, (3) the creation of other toxic pollutants when the fuel is combusted or goes through environmental transformation, and (5) makes toxins available for the air, water, and land. This series of reviews examines the genotoxicity of fuels and their combustion products. Because the term ‘‘genotoxicity’’ was not used until the middle of the twentieth century, terms like ‘‘carcinogenicity’’ must be explored in order to understand the earliest beginnings of environmental genotoxicity and carcinogenicity. Some of the earliest carcinogenic research efforts were done by Horton [314,315]. Russian (at that time known as United Soviet Socialist Republic) scientists Professors Bogovsky and Vo˜sama¨e and their colleagues [316,317] and U.S. scientists Bingham and Barkley and their colleagues [72,219] who took over the work of Horton. When Vo˜sama¨e [317] applied extracts of shale oil to the skin of mice, he showed that shale oil soot was carcinogenic. However, when he by intratracheal application examined the extracts of oil shale soot and tars to random bred albino rats, the rats did not develop epithelial tumors of the lung. In addition, he and his colleagues found no significant rise in the frequency of lung tumors. Vo˜sama¨e concluded ‘‘The results of our study confirm the possibility of the induction of lung tumors by the action of tars from oil shale soot, i.e., from material containing only a small amount of BP [BaP]’’ [317]. In 1979, Bingham and Barkley [72] recognized that the elevated temperatures and altered pressures used in the conversion or processing of shale, coal, and petroleum might cause the formation of polynuclear aromatic hydrocarbons, and that this formation of new compounds might include carcinogens. Many liquid fractions derived from these sources were shown to be

carcinogenic when used in bioassays. They also recognized that benzo(a)pyrene (BaP) could be frequently used as an indicator substance. However, it is clear from their data: (1) all fractions had a small quantity of B(a)P present in a fraction and all fractions examined had some carcinogenic activity, (2) the concentration of BaP in the extracts did not correlate with the numbers of carcinomas or with the number of animals having carcinomas, and, therefore, (3) the results indicated that other carcinogens were present. Also, their work does not indicate that the lack of detectable B(a)P insures that a fraction will be noncarcinogenic.

6. Review of regulations and public policies/practices that concern fuels and mutagenicity and/or carcinogenicity During 1954, President Eisenhower asked that an ad hoc interdepartmental Committee on Community Air Pollution be established [318]. Therefore, an ad hoc Interdepartmental Committee on Community Air Pollution was created with Dr. Leonard A. Scheele (then Surgeon General of the Public Health Service) as chairman of the committee. The committee was composed of representatives of the Departments of Defense, Agriculture, Commerce, Interior, the Atomic Energy Commission, the National Science Foundation, and the Department of Health. The committee recommended legislation authorizing a broad federal program of research and technical assistance in air pollution problems. President Eisenhower recognized the serious nature of the air pollution on several occasions including his ‘‘State of the Union’’ message in January, 1955, in which he called on Congress to take appropriate action against these hazards. With many state and local governments passing different legislative packages concerning air pollution, the federal government decided that this problem needed to be dealt with on a national level. When Congress passed the Air Pollution Control Act of 1955, it was the nation’s first piece of federal legislation on this issue. Congress concluded ‘‘. . . the work under way at present is largely uncoordinated and in need of both acceleration and technical assistance. A solution of the problem is delayed by inadequate observations, insufficient exchange of data, and limited know-how, facilities, and funds.’’ In addition, Congress concluded ‘‘that the Department of Health, Education, and Welfare could best coordinate efforts of federal agencies and cooperate with and aid other bodies, state and local, public and private, in formulating and carrying out research programs directed toward abatement of air pollution.’’ [318]. The Air Pollution Control Act of 1955 (public law 84-159) granted $5 million annually for five years for research by the Public Health Service. The act did little to prevent air pollution, but it made the government aware that this problem existed on a national level. Even though there was concern about inconsistent and stringent laws by state and local governments, state and local governments showed their concern over pollution by passing a number of laws. Rogers [318] notes that during many 1959 sessions a number bills of ‘‘varying significance and interest related to air pollution’’ were introduced into a number of state legislatures. Rogers [318] was able to document the following numbers of bills passed by state legislatures: California, 4; Florida, 3; Idaho, 1; Massachusetts, 1; Oregon, 1; South Carolina, 2; and Tennessee, 1. Although there are many estimates as to the number of local laws for air pollution, the accuracy of such estimates is questionable. In addition, some states and localities had passed other legislation before 1959. By the 1960s, people from all walks of life and from every part of the political spectrum found it obvious that crucial steps had to be taken to correct and prevent future pollution problems [319]. Amendments in 1960 and 1962 extended research funding while reinforcing the principles of the original act.

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In 1962, Rachel Carson’s book Silent Spring [320], which piqued the public’s interest in environmentalism, was first published in serial form in the New Yorker and then as a Houghton Mifflin best seller. This stimulator of the environmental movement was exhaustively researched, carefully reasoned, and beautifully written. At this time, state and local governments began enacting environmental laws, regulating polluters, and banning the use of certain chemicals. The federal government saw that this mass of laws was confusing and often ineffectual, and that the United States needed a comprehensive environmental policy [319]. The Ash Council (1970), a part of President Nixon’s ‘‘President’s Advisory Council on Executive Organization,’’ wrote [321], ‘‘The President’s Advisory Council on Executive Organization recommends that key anti-pollution programs be merged into an Environmental Protection Administration, a new independent agency of the Executive Branch.’’ It was in this atmosphere that the U.S. Environmental Protection Agency was created in 1970. By Executive Order [322], President Nixon ‘‘reorganized’’ the Executive Branch by transferring 15 units from existing organizations into a new independent agency, the USEPA [319]. It took several years for an able Administrator, William D. Ruckelshaus, and employees in the new organization to bring order out of the resulting chaos. During this period, many new environmental laws were passed, some old laws were resurrected and refurbished, and other laws (e.g., energy legislation) impacted the new agency. The Rules and Regulations issued under these laws numbered into many thousands. In its early years, the USEPA alone placed about 1500 rulemaking notices in the Federal Register annually. The first Administrator William D. Ruckelshaus wrote in a press release (December 16, 1970), ‘‘EPA is an independent agency. It has no obligation to promote agriculture or commerce; only the critical obligation to protect and enhance the environment. It does not have a narrow charter to deal with only one aspect of a deteriorating environment; rather it has a broad responsibility for research, standard-setting, monitoring and enforcement with regard to five environmental hazards; air and water pollution, solid waste disposal, radiation, and pesticides. The USEPA presents a coordinated approach to each of these problems, guaranteeing that as we deal with one difficulty we do not aggravate others.’’ Readers

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can get a glimpse of USEPA’s history by reading documents on the EPA web site [319,321–325]. The Clean Air Act (CAA) of 1963 (public law 88-206) bore the words ‘‘clean air’’, in order to promote public health and welfare. The Clean Air Act (codified as 42 U.S.C. 7401) seeks to protect human health and the environment from emissions that pollute ambient air. Note that the CAA applies only to outdoor air. This act sets emissions standards for stationary sources such as power plants and steel mills. This act also recognized the harmfulness of motor vehicle emissions and encouraged the development of emissions standards for mobile sources. The act granted research money to state and local governments and air pollution control agencies. This act also encouraged the use of technology to removed sulfur from high sulfur coal and oil. Amendments of 1965, 1966, 1967 and 1969 targeted: (a) setting standards for automobile emissions, (b) transboundary air pollution, (c) expanding local air pollution control programs, (d) establishing national emissions standards for stationary sources, and (e) extending research to examine low-emission fuels and automobiles. The Motor Vehicle Pollution Control Act of 1965 and the Air Quality Act of 1967 were included in these federal statutes regulating air pollution. The USEPA took ownership of such environmental laws [326]. Elliott et al. [327] argues that this legislation was not passed because environmentalist had national political power but because two well-organized industrial groups (the automobile industry and the soft coal industry) were afraid that states and local rule makers might establish inconsistent and progressively more stringent environmental laws at the state and local level. Facing many different regulations and regulatory organizations, of course, would be even worse from the perspective of industry than federal legislation. See Table 10 for a listing of relevant laws. In the early 1970s, there was a significant growth of legislation designed to improve the quality of life in America by regulating the way industrial facilities contaminate their environments. New laws gave the federal government significant responsibilities. This legislation included the Occupational Safety and Health Act of 1970, the Clean Air Act of 1970 (CAA), the Consumer Product Safety Act of 1972, and the Federal Water Pollution Control Act of 1972 (FWPCA) [328]. These laws gave the federal government significant

Table 10 A listing of U.S. Federal laws that relate to energy (and especially air pollution). Year

Act

Public law number

1955 1959 1960 1963 1965 1966 1967 1970 1973 1974 1977 1978

Air Pollution Control Act Reauthorization Motor vehicle exhaust study Clean Air Act Amendments Motor Vehicle Air Pollution Control Act Clean Air Act Amendments of 1966 Air Quality Act of 1967 and the National Air Emission Standards Act Clean Air Act Amendments of 1970 Reauthorization Energy Supply and Environmental Coordination Act of 1974 Clean Air Act Amendments of 1977 The National Energy Act of 1978 includes the following:  Public Utility Regulatory Policies Act (PURPA)  Energy Tax Act  National Energy Conservation Policy Act (NECPA)  Power Plant and Industrial Fuel Use Act  Natural Gas Policy Act Acid Precipitation Act of 1980 Steel Industry Compliance Extension Act of 1981 Clean Air Act 8-month Extension Clean Air Act Amendments of 1990 Relatively minor laws amending the Act Chemical Safety Information, Site Security and Fuels Regulatory Relief Act Amendments to §209 regarding small engines Energy Policy Act of 2005

P.L. P.L. P.L. P.L. P.L. P.L. P.L. P.L. P.L. P.L. P.L.

1980 1981 1987 1990 1995-96 1999 2004 2005

84-159 86-353 86-493 88-206 89-272, Title I 89-675 90-148 91-604 93-13 93-319 95-95

P.L. 95-617 P.L. 95-618 P. L. 95-619 P. L. 95-620 P. L. 95-621 P.L. 96-294, Title VII P.L. 97-23 P.L. 100-202 P.L. 101-549 P.L. 104-6, 59, 70, 260 P.L. 106-40 P.L. 108-199, Div. G, Title IV, Section 428 P.L. 109-58

Please cite this article in press as: L.D. Claxton, The history, genotoxicity, and carcinogenicity of carbon-based fuels and their emissions: 1. Principles and background, Mutat. Res.: Rev. Mutat. Res. (2014), http://dx.doi.org/10.1016/j.mrrev.2014.07.001

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20

information gathering, oversight, standard-setting, and enforcement responsibilities in many areas formerly regulated, if at all, only by individual states. Although the Clean Air Act of 1970 (public law 91-604) was technically an amendment, this version was a major revision and set very demanding standards. This act established the National Ambient Air Quality Standards (NAAQS) for protecting the public’s health, and New Source Performance Standards (NSPS) for regulating emissions from a new source. The federal government established NAAQS for seven pollutants (lead, sulfur oxides, carbon monoxide, NOx, ozone, hydrocarbons, and PM). NSPS dictated the level of pollution that a new stationary source could produce. NSPSs have been established for several individual source categories (e.g., landfills, boilers, petroleum refineries, turbines, and air emissions from wastewater treatment systems). In addition, standards were set for hazardous emissions from motor vehicles. This Clean Air Act amendment also gave citizens the right to take legal action against anyone or any organization (including the government), who was in violation of the emissions standards. Under this Act, the nation was divided into 247 Air Quality Control Regions (AQCRs) that were to be regulated by each state through a State Implementation Plans (SIPs). Each state SIP was to establish procedures, timetables, and standards (at least as strict as the national standards) for each major pollution source in any AQCR existing in their state. Also, the SIPs were to include a process for approving new sources and significant source modifications. The U.S. Environmental Protection Agency (USEPA) needed to approve the SIP. If a state failed to generate a SIP, the USEPA could control the programs for that state. The amendments of 1977 extended the deadlines for meeting the ambient air standards. For water, each house of congress passed its own bill (‘‘the differences between the two were substantial’’), a final version was developed by a Conference Committee of the two houses of Congress, and a President Nixon veto was overridden before the Federal Water Pollution Control Act (FWPCA) of 1972 was enacted [328]. It provided for complete revision of the prior FWPCA, gave the federal government new roles in pollution abatement, and set up a complex system for the control of water pollution. The

comprehensive and complex goal of the statute was the elimination of the discharge of pollutants into the navigable waters of the United States by 1985. By its language, the FWPCA’s objective is the restoration and maintenance of the ‘‘chemical, physical, and biological integrity of the Nation’s waters.’’ Two of the ‘‘national goals’’ set forth in the Act were: (1) the discharge of pollutants into navigable waters be eliminated by 1985 and (2) that wherever attainable, an interim goal of water quality would provide for the protection and propagation of fish, shellfish, and wildlife and water recreation by July 1, 1983 [328]. The USEPA was made responsible for most aspects of the new FWPCA. However, much of the act was subject to interpretation of the USEPA [328]. More information on water regulation is available [328–331]. In 1990, after over a decade of virtual dormancy, the federal government believed that they should again revise the Clean Air Act due to growing environmental concerns. This also was an attempt to deal with new issues. The Clean Air Act of 1990 (public law 101-549) addressed five main areas: stratospheric ozone depletion, acid rain, air-quality standards, motor vehicle emissions and alternative fuels, and toxic air pollutants. Also, it mandated for new stationary sources the use of the Best Available Control Technology (BACT) to reduce the amount of air toxics. A new source uses the BACT based on a maximum amount of achievable reductions after both cost and technology are considered. As in the past, the act designated the states as being responsible for any non-attainment areas; however, it allowed the states to establish deadlines for each source considering the severity of its pollution. There are several procedures for measuring vehicle emissions for regulatory purposes. The most commonly used are those known as the U.S. Federal, the United Nations Economic Commission for Europe (ECE), and the Japanese test procedures. For light-duty vehicles and motorcycles, the exhaust usually is collected using a constant-volume sampling system while operating the vehicle on a chassis dynamometer. Testing of heavy-duty vehicle engines is done on an engine dynamometer. However, none of the tests fully reflect real-world driving patterns.

Table 11 Emission standards according to Faiz et al. [332], selected examples.a Type of vehicle

Country

Units, Year

CO

HC

NOx

Light-Duty Gasoline or Diesel vehicles Light-Duty Gasoline vehicles Light-Duty Gasoline-vehicles Light-Duty Gasoline- or Diesel vehicles Light-duty vehicles Light-Duty Gasoline-vehicles Light-Duty Diesel vehicles Light-duty vehicles Light-Duty vehicles, Light-Duty Gasoline-vehicles Heavy-duty vehicles Heavy-duty Diesel vehicles Heavy-duty vehicles Heavy-duty vehicles Heavy-duty vehicles Heavy-duty vehicles Motorcycle Motorcycle Motorcycle Motorcycle Motorcycle Mopeds Mopeds Two- and three-wheel vehicles

Argentina Australia Brazil Canada Colombia European Commission European Commission India Mexico United States Brazil Canada China Colombia United States United States Austria Republic of Korea Switzerland United States US-California Austria Switzerland India

g/km, 1999 g/km, 2000 g/km, 1997 g/km, 1988 g/km, 1996 g/km, 2005 proposed g/km, 2005 proposed g/km g/km, 1993 g/mi., 2004 g/kWh, 2002 g/bhp-h, 1988

2.0 2.11 2 2.11 2.3 1.00 0.50 27.1 2.11 1.7 4.0 15.5 5.0 vol% 25.0 15.5 15.5 13.0 3.6 vol% 13.0 12.0 12.0 1.2 0.5 30.0

0.3 0.26 0.3 0.25 0.25 0.10 0.30 HC + NOx 2.9 0.25 0.125 1.1 1.3 2500 ppm 10.0 HC + NOx 1.3 1.3 3.0 450 ppm 3.0 5.0 1.4 1.0 0.5 12.0

0.6 0.63 0.6 0.62 0.62 0.08 0.25

g/bhp-h g/bhp-h, 2004 proposed Opt. A g/bhp-h, 2004 proposed Opt. B g/km, 1991 1996 g/km, 1990 g/km, 1980 g/km, 1980 g/km, 1988 g/km, 1995 g/km, 1995

0.62 0.2 7.0 5.0

See pub. See publication 0.30

PM

0.05 0.16 Diesel

0.025

0.15 0.1 Diesel

0.10 0.10

0.30

0.2 0.10

Abbreviations: CO = carbon monoxide; g/bhp-h = grams per brake horsepower-hour; g/kW-h = grams per kilowatt hour; g/km = grams/kilometer; g/mi/ = grams/mile; HC = hydrocarbons; NOx = nitrogen oxides; NMHC = Non-methane hydrocarbons; PM = particulate matter. a Faiz et al. [332] provide a good accounting of regulatory values as of the year of publication.

Please cite this article in press as: L.D. Claxton, The history, genotoxicity, and carcinogenicity of carbon-based fuels and their emissions: 1. Principles and background, Mutat. Res.: Rev. Mutat. Res. (2014), http://dx.doi.org/10.1016/j.mrrev.2014.07.001

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21

Vehicle emissions in the real world are affected by traffic speed, highway congestion, driving patterns, altitude, temperature, engine characteristics (by the type, size, age, and condition of the engine); and by the emissions control equipment [332]. Differences due to operating conditions can cause emissions to change by more than 100 percent for a given vehicle [332]. While U.S. regulations prohibit crankcase emissions and European regulations specify a test confirming the absence of venting from the crankcase, there is no procedure used by multiple countries for measuring crankcase emissions [332]. See Table 11 for a sample of the regulations of countries for mobile sources (see Faiz et al. [332] for more information).

As John Locke once said, ‘‘Reading furnishes the mind only with materials of knowledge; it is thinking that makes what we read ours.’’ Therefore, I want to think all future researchers and decision makers worldwide who will contribute to the thinking and courage that will be needed to protect the public’s health through protecting the air breathed, the water ingested, and the soils contacted. I also want to acknowledge and thank those researchers who have paved the way and the decision makers who did what was right. Special thanks go to Mutation Research and the editors (David DeMarini and Mike Waters) for their encouragement and assistance.

Conflict of interest statement

Appendix A. Commonly used energy terms, abbreviations and conversion values.

Acknowledgements

The author declares that there are no conflicts of interest.

See Tables A.1 and A.2.

Table A.1 Commonly used energy terms, symbols, abbreviations, and conversions. Term

Symbol

Definition

Useful conversions =42 gallons =159 L

Barrel

Barrel of oil equivalent

(boe)

5.8  106 Btu59 8F

6.12  109 J

British thermal unit (ISO)

BtuISO

B1.0545  103 J

=1.0545 103 J Conversion Table of Common Energy Sources to Btu Gasoline: 1 gallon = 124,000 Btu Diesel Fuel: 1 gallon = 139,000 Btu Heating oil: 1 gallon = 139,000 Btu Electricity: 1 kilowatt hour (kWh) = 3412 Btu (but on average, it takes about 3 times the Btu of primary energy to generate the electricity) Natural Gas: 1 cubic foot (ft3) = 1022 Btu 1 cubic foot = 0.01 therms

British thermal unit (International table)

BtuIT

=1.05505585  103 J =252 International Table calories =1055.05585 J =1.055 kJ

Btu per hour

=.293 W

Calorie (International table)

calIT

B4.1868 J

Calorie (thermochemical)

calth

B4.184 J

=4.1868 J =.00397 Btus =4.184 J 3

Cord

cord

A stack of wood equal to 128 ft . The standard dimensions are 40  40  80 including bark space and air space.

1.2 U.S. tons 2400 lbs 1089 kg

Cubic centimeter of atmosphere

cc atm

B1 atm  1 cm3

=0.101325 J

Cubic foot of atmosphere

cu ft atm

B1 atm  1 ft3

=2.869204 J

B1000 BtuIT

=1.055056 J

Cubic foot of natural gas Drum

=55 gallons

Drum, metric

=52.8 gallon

Electronvolt

eV

Gallon, U.S.

Gal.

Be  1 V

=1.6021773  1019 J =0.833 imperial gallons =.0182 drum =.0189 metric drum =231 cubic inches =0.1337 cubic feet =3.785 L =0.0238 barrels

Please cite this article in press as: L.D. Claxton, The history, genotoxicity, and carcinogenicity of carbon-based fuels and their emissions: 1. Principles and background, Mutat. Res.: Rev. Mutat. Res. (2014), http://dx.doi.org/10.1016/j.mrrev.2014.07.001

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22 Table A.1 (Continued ) Term

Symbol

Gallon, imperial

Definition

Useful conversions

B4.54609 L

=4.55 L

Gigajoule

GJ

B109 J

=0.948  106 Btu Or = 947,817.12 Btu =239  106 cal =278 kWh

Horsepower

hp

B550 foot-pounds per second (mechanical horsepower)

=2545 Btu/h =745.7 watts =0.746 kW

Horsepower-hour

hp h

B1 hp  1 h

=2.6485195  106 J

Joule (SI unit)

J

The work done when a force of 1 Newton moves the point of its application a distance of 1 m in the direction of the force.

=1 m N =kg m2/s2 =0.239 cal =.0009478 Btus

Kilocalorie

kcal

B1000  calIT

=4.1868  103 J

B1000 J

=.9479 Btus

Kilowatt

kW

=3413 Btu/h

=1.341 horsepower

Kilowatt-hour

kW h

B1 kW  1 h =3413 Btu

=3.6  106 J =3.6 MJ

Liter

L

Liter-atmosphere

1 atm

Kilojoule

=0.264 U.S. gallons =0.220 imperial gallons =.00629 barrels B1 atm  1 L 15

Quad

B10

Therm (U.S.)

B100,000 Btu59?F

Ton, U.S.

B2000 pounds

Ton, imperial

B2240 pounds

Ton, metric

B1000 kg

BtuIT

3

Ton, metric, wood

=1.4 m (solid wood, no stacked)

=101.325 J =1.0550559  1018 J =1.055 EJ (exajoules) 172 million barrels of oil equivalent (106 boe) =105.4804  106 J

=2205 pounds =18–22 GJ/ton (bone dry) =7600–9000 Btu/pound =15 GJ/ton (20% moisture) =6400 Btu/pound (20% moisture)

Ton, metric, agriculture residue

=10–17 GJ =4300–7300 Btu/pound

Ton, metric, charcoal

30 GJ 12,800 Btu/pound

Ton, metric, ethanol

=1262 L

=11,500 Btu/pound =74,700 Btu/gallon =26.7 GJ/ton =21.1 MJ/L

Ton of coal equivalent

TCE

B7 Gcalth

=29.3076  109 J

Ton of oil equivalent

TOE

B10 Gcalth

=41.868  109 J

B1.0 J/s

=3.413 Btu/h

Watt Watt hour

Wh

=3600 J

The author has rounded off values at seven significant figures after the decimal point. Go to more authoritative sources for more precise values. Values from: Oak Ridge National Laboratory (http://bioenergy.ornl.gov/papers/misc/energy_conv.html) [333], U.S. National Institute of Standards and technology (www.nist.gov/owm or www.nist.gov/metric or http://www.nist.gov/pml/wmd/h44-12.cfm), Energy Information Administration, (http://www.eia.doe.gov/), Measurement Converter, Convertit.com, (http://www.convertit.com/Go/ConvertIt/), Iowa Energy Center, Iowa State University, (http://www.energy.iastate.edu/), Biomass Energy Datebook, U.S. Department of Energy, (http://cta.ornl.gov/bedb/appendix_a.shtml), and BP Conversion Factors: (http://www.bp.com/conversionfactors.jsp). See the ORNL site for their useful ‘‘Glossary of Bioenergy Terms’’ (http://bioenergy.ornl.gov/faqs/glossary.html) [334]. Useful prefixes include: deka = 10, hecto = 100 = 102, kilo = thousand = 103, mega = million = 106, giga = billion = 109, tera = trillion = 1012.

Please cite this article in press as: L.D. Claxton, The history, genotoxicity, and carcinogenicity of carbon-based fuels and their emissions: 1. Principles and background, Mutat. Res.: Rev. Mutat. Res. (2014), http://dx.doi.org/10.1016/j.mrrev.2014.07.001

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23

Table A.2 Conversions used in these papers. Convert from

Convert to

Multiply by

Source

Barrel, oil (42 U.S. gallons) Gallon Mile per gallon Kilowatt hour Btu Therm (U.S.) Btu per second

Liter (L) Liter (L) Kilometer per liter Megajoule (MJ) Kilojoule (kJ) Megajoule (MJ) Kilowatt (kW)

158.9837 3.785412 0.4251437 3.6 1.055056 105.4804 1.055056

[335] [335] [335] [335] [335] [335] [335]

Appendix B. Physiochemical and other useful facts about fuels Information in this appendix is a compilation from: Biomass Energy Data Book, U.S. Department of Energy (https://cta.ornl.gov/ bedb/appendix_a.shtml); Bioenergy Feedstock Network (http:// bioenergy.ornl.gov/); Energy Information Administration (http:// www.eia.doe.gov/kids/energyfacts/science/energy_calculator. html); Measurement Converter (http://www.convertit.com/ Go/ ConvertIt/Measurement/Converter.ASP); D. Hofstrand, Energy Measurements and Conversions (File C6-86), (http://www.extension. iastate.edu/agdm/wholefarm/html/c6-86.html); D. Hofstrand, Energy Measurements and Conversions, Iowa State University, Extension and Outreach, 2008 (http://www.extension.iastate.edu/ agdm/wholefarm/html/c6-86.html); and Wikipedia (http://en. wikipedia.org/wiki/Fuel_efficiency). When determining the heat energy obtained when a certain quantity (e.g., a gallon, a liter, and a kilogram) is burned, the specific energy content of a fuel (sometimes called the heat of combustion) is derived. There are two different values (HHV and

LHV) of specific heat energy for the same batch of fuel. Therefore, in some of the information below, HHV and LLV are given. These abbreviations are for High Heating Value and Lower Heating Value, respectively. The HHV is larger since it includes the latent heat of vaporization of water. In most cases, LHV is the closest value to the actual energy yield. HHV is greater by between 5% (in the case of coal) and 10% (for natural gas), depending mainly on the hydrogen content of the fuel. For most biomass feed-stocks, this difference appears to be 6–7%. In the U.S., the HHV has traditionally been used, but in many other countries, the LHV is commonly used. See other sources when deciding which value to use. Neither the gross heat of combustion nor the net heat of combustion gives the theoretical amount of mechanical energy (work) that can be obtained from a reaction. This is given by the change in Gibbs free energy. The actual amount of mechanical work obtained from fuel (the inverse of the specific fuel consumption) depends on the engine. See Tables B.1–B.4.

Table B.1 Energy values associated with fuels. Fuel

Gasoline

Diesel fuel

Biodiesel

Ethanol

Methanol

Energy valuesa HHV

LHV

Comments

Gallon = 125,000 Btu Gallon = 131.9 MJ Barrel = 5,250,000 Btu Barrel = 5539 MJ Liter = 33,025 Btu Liter = 34.8 MJ

Gallon = 115,400 Btu Gallon = 121.7 MJ Barrel = 4,846,800 Btu Barrel = 5113 MJ Liter = 30,489 Btu Liter = 32.2 MJ

Gallon = .002791 metric tons

Gallon = 138,700 Btu Gallon = 146.3 MJ Barrel = 5,825,400 Btu Barrel = 6146 MJ Liter = 36,645 Btu Liter = 38.7 MJ

Gallon = 128,700 Btu Gallon = 135.8 MJ Barrel = 5,405,400 Btu Barrel = 5703 MJ Liter = 34,003 Btu Liter = 35.9 MJ

Gallon = 0.003192 metric tons

Gallon = 126,206 Btu Gallon = 133.1 MJ Barrel = 5,300,652 Btu Barrel = 5592 MJ Liter = 33,344 Btu Liter = 35.2 MJ

Gallon = 117,093 Btu Gallon = 123.5 MJ Barrel = 4,917,906 Btu Barrel = 5188 MJ Liter = 30,936 Btu Liter = 32.6 MJ

Metric ton = 37.8

Gallon = 84,600 Btu Gallon = 89.3 MJ Barrel = 3,553,200 Btu Barrel = 3749 MJ Liter = 22,351 Btu Liter = 23.6 MJ

Gallon = 75,670 Btu Gallon = 79.8 MJ Barrel = 3,178,140 Btu Barrel = 3353 MJ Liter = 19.992 Btu Liter = 21.1 MJ

Gallon = 64,600 Btu Gallon = 68.2 MJ Barrel = 2713,200 Btu Barrel = 2862 MJ Liter = 17,067 Btu Liter = 18.0 MJ

Gallon = 56,560 Btu Gallon = 59.7 MJ Barrel = 2,375,520 Btu Barrel = 2506 MJ Liter = 14,943 Btu Liter = 15.8 MJ

Barrel = 0.1172 metric tons

Barrel = 0.1341 metric tons

Average density = 0.88 grams per milliliter Average density = 0.88 metric tons per cubic meter

Average density = 0.79 grams per milliliter Average density = 0.79 metric tons per cubic meter

Please cite this article in press as: L.D. Claxton, The history, genotoxicity, and carcinogenicity of carbon-based fuels and their emissions: 1. Principles and background, Mutat. Res.: Rev. Mutat. Res. (2014), http://dx.doi.org/10.1016/j.mrrev.2014.07.001

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24 Table B.1 (Continued ) Fuel

Energy valuesa HHV

LHV

Residual fuel

Gallon = 149,700 Btu Gallon = 157.9 MJ Barrel = 6,287,400 Btu Barrel = 6633 MJ Liter = 39,551 Btu Liter = 41.7 MJ

Gallon = 138,400 Btu Gallon = 146.0 MJ Barrel = 5,812,800 Btu Barrel = 6133 MJ Liter = 36,565 Btu Liter = 38.6 MJ

LP gas (liquefied petroleum gas–propane)

Gallon = 91,300 Btu Gallon = 96.3 MJ Barrel = 3,834,600 Btu Barrel = 4046 MJ Liter = 24,121 Btu Liter = 25.4 MJ

Gallon = 83,500 Btu Gallon = 88.1 MJ Barrel = 3,507,000 Btu Barrel = 3700 MJ Liter = 22,061 Btu Liter = 23.3 MJ

Butane

Gallon = 103,000 Btu Gallon = 108.7 MJ Barrel = 4,326,000 Btu Barrel = 4564 MJ Liter = 27,213 Btu Liter = 28.7 MJ

Gallon = 93,000 Btu Gallon = 98.1 MJ Barrel = 3,906,000 Btu Barrel = 4121 MJ Liter = 24,571 Btu Liter = 25.9 MJ

Crude oil

Gallon = 138,100 Btu Gallon = 145.7 MJ Barrel = 5,800,200 Btu Barrel = 6119 MJ Liter = 36,486 Btu Liter = 38.5 MJ

Gallon = 131,800 Btu Gallon = 139.0 MJ Barrel = 5,535,600 Btu Barrel = 5840 MJ Liter = 34,822 Btu Liter = 36.7 MJ

Natural gasa

Gallon–liquid = 90,800 Btu 1 metric ton LNG = 48,700 cubic feet of natural gas Cubic meter – dry = 36,409 Btu Cubic meter – dry = 38.140 MJ

Gallon–liquid = 87,600 Btu

Coala

Pound = 10,377 Btu Pound = 10.948 MJ Short ton (2000 lbs) of coal = 20,754,000 Btu Short ton = 21,897 MJ Short ton = .907 metric tons Metric ton = 22,877,388 Btu Metric ton = 24,137 MJ

Comments

MJ = megajoules, LNG = Liquefied natural gas a The HHV and LHV were not given in some cases.

Table B.3 Automotive fuel usage measurements and conversions.

Table B.2 Biomass measurements with equivalent energy amounts (conversions). Biomass

Measurement or conversion

1 1 1 1 1 1 1 1 1 1 1 1

=12,800 Btu =7341 Btu =6065 Btu =6575 Btu =6187 Btu =7600–9600 Btu (HHV) 6400 Btu =4300–7300 Btu =30 GJ =10–17 GJ =18–22 GJ (HHV) 15 GJ

pound of charcoal pound of switchgrass pound of bagasse (waste pulp from sugarcane) pound of rice hulls pound of poultry litter pound of wood fuel (bone dry) pound of wood fuel (air dry–20% moist.) pound of agricultural residue (varying moist.) metric ton of charcoal ton of agricultural residue (varying moisture) ton of wood fuel (bone dry) ton of wood fuel (air dry – 20% moist.)

Starting basis

Measurements/conversions

1 mile per gallon

=0.264 miles per liter =0.425 kilometers per liter !235 liters per 100 kilometers

1 kilometer per liter

=2.35 miles per gallon =0.6215 miles per liter !42.5 gallons per 100 miles

1 mile per liter

=3.79 miles per gallon =1.609 kilometers per liter !62.15 liters per 100 kilometers

Notes: ! to be read as ‘‘equivalent to.’’

Table B.4 Examples of carbon content of fossil fuels and bioenergy feedstocks. Fuel

Amount of carbon

Coal (average) Coal Oil (average) Gasoline Diesel/fuel oil Natural gas (methane) Natural gas (methane) Woody crops or wood waste Graminaceous (grass) crops or agricultural residues

25.4 metric tons carbon per terajoule (TJ) Metric ton coal = 746 kg carbon 19.9 metric tons carbon/TJ 1.0 US gallon = 2.42 kg carbon 1.0 US gallon = 2.77 kg carbon 14.4 metric tons carbon/TJ 1.0 cubic meter = 0.49 kg carbon About 50% carbon About 45% carbon

Please cite this article in press as: L.D. Claxton, The history, genotoxicity, and carcinogenicity of carbon-based fuels and their emissions: 1. Principles and background, Mutat. Res.: Rev. Mutat. Res. (2014), http://dx.doi.org/10.1016/j.mrrev.2014.07.001

G Model

MUTREV-8086; No. of Pages 32 L.D. Claxton / Mutation Research xxx (2014) xxx–xxx

Appendix C. Abbreviations used in this series of reviews and other publications. Abbreviation

Meaning



Approximately (used as an indication of approximation) l-Hydroxypyrene Automobile DEP Adenocarcinoma of the lung American Petroleum Institute Air Quality Control Regions Above-ground storage tanks Best Available Control Technology Benzo(a)pyrene or 1:2-benzpyrene or 3:4benzpyrene or benzpyrene Bioassay-directed fractionation (also known as EDA) Biomass-based fuels Barrels of oil energy equivalent Biopile (a biodegradation method for waste) Bioslurry (a biodegradation method for waste) Benzene, toluene, ethylbenzene, and the xylenes Naphthalene plus Total BTEX Styrene plus Total BTEX British thermal unit (See Table A.1) Carbon-14 Clean Air Act The Clean Air Act Amendments Calorie (see Table A.1) California Air Resources Board Carbon black Coal combustion products Compressor-generated DEP Comprehensive Environmental Response, Compensation, and Liability Act Council on Environmental Quality Commercial chemical products Confidence interval Confidence interval – XX%; for example, CI95% = CI95% Compost (a biodegradation method for waste) Compressed natural gas Compressed natural gas vehicles Ethanol Carbon dioxide Chloroperoxyacetyl nitrate Coal to liquids, the chain of chemical processes to transform coal into liquid hydrocarbons Clean Water Act Deaths and disability-adjusted life years Dichloromethane Diesel exhaust particles Diesel fuel Diisopropyl ether Dimethyl carbonate Dimethyl ether Dimethylhydrazine Diesel oxidation catalytic converters Diesel (emission) particles Diesel particulate filters United Nations – Economic Commission for Europe Effect-directed analysis (also known as BDF) Exhaust Gas Recirculation: When combustion temperatures exceed 2500 F, atmospheric nitrogen begins to react with oxygen during combustion resulting in NOx. The EGR valve controls a small passageway between the intake and exhaust manifolds that dilutes the incoming air/fuel mixture, quenches combustion temperatures, and keeps NOx within acceptable limits. 2007 Energy Independence and Security Act Extractable organic matter Enhanced oil recovery U.S. Energy Information Administration Electrostatic precipitator Ethyl tert-butyl ether Environmental tobacco smoke (also known as SHS) Ethanol European Union Equilon ULSD (an ultra-low sulfur diesel fuel) Electric vehicles

1-OHP A-DEP ADL API AQCRs ASTs BACT BaP BDF BMFs boe BP BS BTEX BTEXN BTEXS Btu 14 C CAA CAAAs cal CARB CB CCPs C-DEP CERCLA or Superfund CEQ CCPs CI CIXX% CMP CNG CNGVs CH3CH2OH CO2 CPAN CTL CWA DALYs DCM DEPs DF DIPE DMC DME DMH DOCCs DP DPFs ECE EDA EGR

EISA EOM EOR EIA ESP ETBE ETS EtOH EU EULSD EVs

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Appendix C (Continued ) Abbreviation

Meaning

FAME FCEVs FFV FIFRA FWPCA GC/MS gge

Fatty-acid methyl ester Fuel cell electric vehicles Flexible Fuel Vehicle Federal Insecticide, Fungicide, and Rodenticide Act Federal Water Pollution Control Act Gas chromatography-mass spectrometry The amount of fuel with the same energy content as a gallon of gasoline Green house gas Gas to liquids, a refinery process Hydrocarbon Heavy duty diesel engine Hybrid electric vehicles High performance liquid chromatography Highway maintenance workers Hydrotreated coal Hydrazine International Agency for Research on Cancer Internal combustion engines Internal combustion engine vehicles Intraperitoneal Joule (see Table A.1) Kilojoule (see Table A.1) In toxicity assays, the dose at which 50% of the test animals die Light duty diesel engines Light-duty vehicles Lower heating value Liquefied natural gas Liquefied petroleum gas Land treatment (a biodegradation method for waste) Middle distillates Middle distillate fuels Methanol Motorcycle exhaust particles Multilinear regression Monomethylhydrazine Methylcyclopentadienyl manganese tricarbonyl Micronucleus or micronuclei or micronucleus assay Miles per gallon of gasoline equivalent Methylcyclopentadienyl manganese tricarbonyl Methyl tertbutyl ether National Ambient Air Quality Standards Nonaqueous phase liquids National Academy of Science Noncommunicable disease(s) National Institute of Standards and Technology DEP, the Network for Environmental Risk Assessment and Management Natural gas National Institute of Environmental Health Sciences (a part of NIH) National Institutes of Health Nitrogen oxide Nitrogen oxides National Research Council New Source Performance Standards Ozone Oxidation catalyst Organization of Arab Petroleum Exporting Countries Polycyclic aromatic compounds: organic compounds composed of two or more fused benzene rings Polyaromatic hydrocarbon Peroxyacetyl nitrate, CH3C(O)OONO2 Peroxybutyryl nitrate Peroxybenzoyl nitrate Polychlorinated biphenyls Polychlorinated dibenzodioxins/furans Plug-in electric vehicles (includes BEVs and PHEVs) Platinum group metal (Pt, Pd, and Rh) Plug-in hybrid electric vehicles Particulate matter (a subscript indicates the largest size in mm for the particulate matter sampled) Particulate matter

The history, genotoxicity, and carcinogenicity of carbon-based fuels and their emissions: 1. Principles and background.

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