Environmental Research 133 (2014) 27–35
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Formaldehyde: A chemical of concern in the vicinity of MBT plants of municipal solid waste Lolita Vilavert a, María J. Figueras b, Marta Schuhmacher a,c, Martí Nadal a,n, José L. Domingo a a
Laboratory of Toxicology and Environmental Health, School of Medicine, Universitat Rovira i Virgili, Sant Llorenç 21, 43201 Reus, Catalonia, Spain Microbiology Unit, School of Medicine, Universitat Rovira i Virgili, Sant Llorenç 21, 43201 Reus, Catalonia, Spain c Environmental Engineering Laboratory, Departament d’Enginyeria Quimica, Universitat Rovira i Virgili, Av. Països Catalans 26, 43007 Tarragona, Catalonia, Spain b
art ic l e i nf o
a b s t r a c t
Article history: Received 12 March 2014 Received in revised form 11 April 2014 Accepted 24 April 2014
The mechanical–biological treatment (MBT) of municipal solid waste (MSW) has a number of advantages in comparison to other MSW management possibilities. However, adverse health effects related to this practice are not well known yet, as a varied typology of microbiological and chemical agents may be generated and released. In 2010, we initiated an environmental monitoring program to control air levels of volatile organic compounds (VOCs) and microbiological pollutants near an MBT plant in Montcada i Reixac (Catalonia, Spain). In order to assess any temporal and seasonal trends, four 6-monthly campaigns were performed. Important ﬂuctuations were observed in the levels of different biological indicators (total and Gram-negative bacteria, fungi grown at 25 1C and 37 1C, and more speciﬁcally, Aspergillus fumigatus). Although overall bioaerosols concentrations were rather low, a certain increase in the mean values of bacteria and fungi was observed in summer. In contrast, higher concentrations of VOCs were found in winter, with the only exception of formaldehyde. Interestingly, although this compound was not detected in one of the sampling campaigns, current airborne levels of formaldehyde were higher than those previously reported in urban areas across Europe. Furthermore, the non-carcinogenic risks (Hazard Quotient), particularly in winter, as well as the cancer risks associated with the inhalation of VOCs, exceeded the threshold values (1 and 10 5, respectively), reafﬁrming the need of continuing with the monitoring program, with special emphasis on formaldehyde, a carcinogenic/mutagenic substance. & 2014 Elsevier Inc. All rights reserved.
Keywords: Mechanical–biological treatment plant Volatile organic compounds (VOCs) Formaldehyde Bioaerosols Human health risks
1. Introduction Municipal solid waste (MSW) is a serious problem in today’s society. MSW is generated in large quantities, meaning a danger to the environment and public health (Baptista et al., 2011). In Europe, the basic concepts and deﬁnitions described about waste management were established by the Waste Framework Directive 2008/98/EC. It is commonly accepted that the main priority of this regulatory measure is reducing or preventing the quantity of waste. A number of studies show that one of the best options for treatment is either separation or non-mixing at the source (Aranda Usón et al., 2012). Nowadays, there are in Europe approximately 2000 composting facilities, 185 anaerobic digestions plants and 180 mechanical– biological treatment (MBT) plants treating organic municipal waste (Boldrin et al., 2011). The main objective in an MBT facility is to separate biodegradable and non-biodegradable components through
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http://dx.doi.org/10.1016/j.envres.2014.04.041 0013-9351/& 2014 Elsevier Inc. All rights reserved.
either composting or anaerobic digestion (Donovan et al., 2010). However, MBT also have some disadvantages, since a signiﬁcant amount of hazardous compounds may be released into the atmosphere during the waste sorting, composting, and compost reﬁning (Giusti, 2009; Pankhurst et al., 2011; Sykes et al., 2011). Exposure to biological particulates suspended in air, known as bioaerosols or “organic dust”, may lead to different pathologies (Su et al., 2002; Grisoli et al., 2009), such as inﬂammatory (chronic bronchitis), irritative reactions (contact dermatitis, upper and lower respiratory tracts, asthma…), allergic/immunoallergic responses (rhinitis, allergic asthma, sinusitis, hypersensitivity pneumonitis, and organic dust toxic syndrome), as well as infections, such as invasive aspergillosis in immunosuppressed subjects (Douwes et al., 2008; Rusca et al., 2008; Persoons et al., 2010; Dutkiewicz et al., 2011; Madsen et al., 2012; Tuntevski et al., 2013; Viegas et al., 2014). On the other hand, volatile organic compounds (VOCs) are major air pollutants characterized by their malodorous and dangerous properties, being also released in air in waste composting processes (Domingo and Nadal, 2009; ADEME, 2012). Benzene, toluene, ethylbenzene and xylene (BTEX) form an important group
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of aromatic VOCs, having a role in the troposphere chemistry, as ozone precursors (Fang et al., 2013), and meaning a risk to human health. Furthermore, they have been signiﬁcantly associated with odour annoyance in different studies (Atari et al., 2013). Regarding air quality, current European standards establish a maximum atmospheric benzene level of 5 mg/m3. Benzene, 1,3-butadiene and formaldehyde have been classiﬁed as known human carcinogens by the International Agency for Cancer Research (Yazar et al., 2011), while the two latter are also among the substances with the greatest risk to human health protection in the atmosphere (Nakamura et al., 2008). Moreover, it has been evidenced that children can be more sensitive to formaldehyde toxicity than adults (Pegas et al., 2011). Odors are one of the most critical problems for the neighborhood of MBT plants and composting facilities, having been even associated to various physical symptoms among residents in the surrounding areas (Aatamila et al., 2011). These odors are not only related to the presence of VOCs, but also to the occurrence of microbiological organisms, deriving in a long series of health symptoms (e.g., headache, respiratory problems, eye, nose and throat symptoms, nausea, weakness, and diarrhea) (Curtis et al., 2006; Krajewski et al., 2004; Eduard et al., 2001). In recent years, the proliferation of MBT plants has been particularly remarkable in Spain (Vásquez et al., 2012; Montejo et al., 2013). MBT plants are called Ecoparcs in Catalonia (Spain). The main aim of these facilities is to achieve a valorization of energy and materials through two lines. First, by treating the organic fraction, and second by managing the remaining fraction. In addition, Ecoparcs seek to minimize the amount of waste and to improve its characteristics to ﬁt with the EU legislation. Three Ecoparcs are currently operating in the metropolitan area of Barcelona (Catalonia), while others have recently initiated their operations in Catalonia (e.g., Mataró, Botarell). One of these, Ecoparc-2 (Montcada i Reixac, Catalonia, Spain), is currently managing an important percentage of the municipal waste organic fraction generated within the metropolitan area of Barcelona. We recently determined the levels of VOCs and microbiological pollutants in different indoor work of that facility, assessing the potential hazards for the workers. As relatively high indoor levels of those pollutants were found (Nadal et al., 2009), the implementation of a surveillance program to evaluate the impact of Ecoparc-2 on the surrounding environment was planned and executed. In 2010, this program was initiated by monitoring air levels of VOCs and microbiological pollutants. The ﬁrst part of the program was focused on analyzing the environmental burdens and any potential seasonal differences (Vilavert et al., 2012). As the
concentrations of environmental pollutants may vary over time, the program was extended to evaluate also the temporal trends of both, chemical and microbiological agents. The aim of the present study was to determine the environmental concentrations of VOCs and microorganisms (bacteria and fungi) in the vicinity of the Ecoparc-2 placed in Montcada i Reixac (Catalonia, Spain), as well as to deﬁne their temporal and seasonal trends. Finally, the health risks derived from exposure to those chemicals agents were characterized for the population living near the facility.
2. Materials and methods 2.1. Area of study The Ecoparc-2 is located in Montcada i Reixac (Catalonia, Spain). Its construction was started in 2001, and it has been working since 2004. The input material includes the organic fractions of the MSW, as well as vegetal residues of gardens and parks from several municipalities of the metropolitan area of Barcelona. It has a total capacity for the integral treatment of 240,000 t of MSW per year. During the process, 23,000 t/year of material is recovered, while 38,000 t/year of quality compost is produced. In addition, 12.6 million m3 of biogas is generated (electric production: 16,000 MWh per year). In January 2010, a surveillance program was initiated to monitor the airborne levels of VOCs and bioaerosols (Vilavert et al., 2012). In order to study temporal/seasonal trends, four 6-monthly campaigns were performed until July 2011. In each survey, air was sampled in 12 points around the MBT plant. Samples were taken at 3 distances (300, 600 and 900 m) and different wind directions (N, SE, SW and W) from the facility, according to the results of a previously applied fate and transport model. The location of the sampling points is shown in Fig. 1. In order to verify the results of the monitoring program, as well as the suitability of the sampling sites, air levels of VOCs were estimated by executing again the ISC-AERMOD View (Lakes Environmental Software, Waterloo, Ontario, Canada). This is a complete and powerful air dispersion modeling package, which incorporates popular U.S. EPA models, ISCST3, ISC-PRIME and AERMOD into one interface without any modiﬁcations on the models. For that purpose, a single emission sample in the stack gas was additionally included, while local meteorological data was obtained from automatic stations. The modeling results are shown in Fig. 2. A total of 453 receptors were selected, including 12 original sites. VOCs were preferably dispersed in 3 directions (N, SE, and W), while SW was chosen as background. The presence of other potential emission sources, as well as that of sensitive population was also taken into account. Special attention was paid on N1 and SW3, where a pig farm and a school, respectively, were located (Vilavert et al., 2012).
2.2. Analytical methods Because of the strong expected variability in microbial concentrations, ﬁve replicates of air samples were collected at each sampling point. The occurrence of the following micro-organisms was studied: total bacteria and fungi as general indicators, Gram-negative bacteria as indicators of opportunistic pathogens, and speciﬁcally Aspergillus fumigatus as fungus that might mean a potentially remarkable risk for the population. The sampling was performed by using a Sampl’Air Lite
Fig. 1. Distribution of 12 sampling points around an MBT plant in Montcada i Reixac (Catalonia, Spain).
0. 01 1
5 01 0.
L. Vilavert et al. / Environmental Research 133 (2014) 27–35
0. 01 8
0. 01 8
1 01 0.
0. 01 8
1 01 0.
1 01 0.
4 00 0.
Fig. 2. Modeled VOC concentrations in air as estimated by AERMOD.
device (AES Laboratoires, Bruz, France), with an air-ﬂow rate set at 100 L/min. The sampling time was established at 3 min for Gram-negative bacteria, and 1 min for the remaining target agents. Air was forced to pass Petri dishes with a speciﬁc culture media: Triptyc Soy Agar (TSA), McConkey and Potato Dextrose Agar (PDA) for total bacteria, Gram-negative bacteria and fungi, respectively. Immediately after sampling, Petri dishes were transported to the lab and kept in the stove. Samples were incubated for 48 h at 37 1C for the analyses of total bacteria, and 24 h for the determination of Gram-negative bacteria. PDA was incubated at 25 1C and 37 1C for 5–7 days for the determination of fungi. Microbiological results were expressed as the total number of colony-forming units (cfu) per m3 of air. In two of the 5 fungi samples, a detailed study on the number of colonies of A. fumigatus was performed. If the total number of colonies exceeded 200 in a Petri dish, results were expressed, according to the ISO 8199:2005 standard, as too numerous to count, being not included in the statistical analysis. On the other hand, a sampling pump Airchek 2000 SKC (Vertex, L’Hospitalet de Llobregat, Spain) was used to sample air for subsequent analysis of VOCs. Samples were collected by passing air through an Anasorb 747 sorbent tube (SKC Inc., Eighty Four, PA, USA), in which all compounds, with the only exception of formaldehyde, were adsorbed. The retention of this chemical was done by using a 2,4-dinitrophenylhydrazine (2,4-DNPH) coated silica gel tube (SKC Inc., Eighty Four, PA, USA). Total volumes of air were approximately 360 L for most VOCs, and 180 L for formaldehyde. Samples were rapidly transported to the lab, where they were kept at 20 1C until analysis. Most compounds were extracted by liquid desorption with 1–3 mL of carbon sulﬁde for at least 60 min. Analysis was carried out by using a gas chromatograph coupled to a mass spectrometer (GC–MS) equipped with a Rtx-1 fused-silica capillary column (30 m 0.32 mm 1.5 mm). The oven temperature started at 40 1C, and kept for 1 min. Then, it was raised at 14.9 1C/min up to 220 1C, where a new ramp of 40 1C/min was initiated until 320 1C. Helium was used as carrier gas. In turn, formaldehyde was desorbed from tubes with 2 mL of acetonitrile in an ultrasonic bath for 30 min. The analysis was done by high pressure liquid chromatography with UV detection (HPLC-UV), using a C-18 column (5 mm, 200 cm 4.6 mm). The initial mobile phase was acetonitrile:water (50:50). The gradient program for acetonitrile, given as time–concentration percentage, was the following: min 0.1–50%, min 5–50%, min 20–80%, min 25–100%, min 48–50%, and min 52 – stop. The quality control/quality assurance was checked by analyzing
blank and replicate samples. Calibration was done by using standard solutions of VOCs in CS2 and DNPH derivatives of aliphatic aldehydes in acetonitrile for the determination of VOCs and formaldehyde, respectively. Detection limits differed according to each speciﬁc VOC, ranging from 0.05 to 5 mg/m3.
2.3. Human health risks Human exposure to VOCs was evaluated according to the standard methodology developed by the United States Environmental Protection Agency (US EPA, 2009). Because all the studied contaminants are volatile, inhalation was considered to be the main exposure pathway, especially for some VOCs such as xylenes or ethylbenzene (Pérez-Rial et al., 2010; Sarma et al., 2010). Exposure concentration (EC) was ﬁrst calculated by applying the following equation: EC inh ¼
C air ET EF ED AT 365 24
where ECinh is the exposure concentration (in μg/m3), Cair is the air concentration of each VOC (in μg/m3), ET is the exposure time (24 h day 1), EF is the exposure frequency (350 days year 1), ED is the exposure duration (30 years), and AT is the averaging time (30 years for non-carcinogenic substances and 70 years for carcinogenic chemicals). Furthermore, the non-cancer risk (Hazard Quotient, HQ), due to exposure to each individual compound, was estimated by comparing ECinh and the inhalation reference concentration (RfCi, in μg/m3): HQ inh ¼
EC inh Rf C
In turn, the carcinogenic risk was calculated by multiplying ECinh by the US EPA Inhalation Unit Risk (IUR, in (μg/m3) 1): Cancer Riskinh ¼ ECxIUR To date, there is no reliable information yet to assess human health risks derived from microbiological exposure. Therefore, health risks were evaluated only for chemical pollutants.
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2.4. Statistical methods used Data analyses were performed by using the IBM SPSS Statistics 19.0 statistical software package. The Levene test was applied to analyze the equality of variances. ANOVA or U-Mann Whitney tests were then executed depending on whether data presented a normal distribution or not, respectively. A probability lower than 0.05 (po0.05) was considered as signiﬁcant. For calculation purposes, undetected pollutants were assumed to have a concentration of zero (ND¼ 0).
3. Results and discussion 3.1. Bioaerosol and VOC concentrations The levels of microbiological pollutants and VOCs in air samples collected around the Ecoparc-2 in Montcada i Reixac during four 6-monthly campaigns are summarized in Table 1. Regarding bioaerosols, fungi at 25 1C showed the highest levels in the four campaigns, with mean values ranging between 1097 cfu/m3, in summer of 2011, and 2152 cfu/m3, in winter of 2010. A slight seasonal pattern was noted, being levels lower in summer than in winter campaigns. Anyhow, this variation was only statistically signiﬁcant between winter of 2010 and summer of 2011 (Fig. 3). Total bacteria showed a strong variability depending on each sampling, being the concentrations in winter 2010 signiﬁcantly lower (po0.05) than those observed in summer of 2010 and in winter of 2011 (427% and 184%, respectively). Anyway, concentrations were higher in summer campaigns. Gram-negative bacteria presented very low levels during the whole study, with mean values ranging between 2 and 5 cfu/m3. Fungi at 37 1C showed a certain seasonal trend, with higher signiﬁcant values in summer collections than in winter (po0.05). However, an important decline was observed between summer 2010 and 2011, when values signiﬁcantly decreased from 712 to 106 cfu/m3. Finally, A. fumigatus was not detected in most samples, irrespective of the growth temperature (25 1C or 37 1C). The seasonal and temporal trends for bioaerosols as well as VOCs – including BTEX and formadehyde – are shown in Fig. 3. No seasonal or temporal trends could be noted in this study for Gram-negative bacteria and A. fumigatus cultivated at two different temperatures. These results are in agreement with those reported in a number of scientiﬁc studies, despite of the fact that data on the levels of bioaerosols in the vicinity of waste treatment plants are certainly very scarce. In a recent study performed near a municipal solid waste incinerator in Tarragona, we found airborne mean levels of total and Gram-negative bacteria ranging 186–388 and 1–10 cfu/m3, respectively, while fungi were found at concentrations of 1039–1856 cfu/m3 and 89–226 cfu/m3 (at 25 1C and 37 1C, respectively) (Vilavert et al., 2011), being therefore very similar to those found in the surroundings of Ecoparc-2. In India, bacterial levels in a public garden site were recently found to range from 940 to 12,260 cfu/m3, while those impacted by trafﬁc were between 1560 and 17,060 cfu/m3. A similar pattern was reported for air fungi, as ranges were 220–1020 and 220– 1560 cfu/m3 in the same respective sampling locations (Kumar et al., 2011). In addition to outdoor studies, the incidence of bioaerosols inside waste treatment facilities has been widely studied in the past. In the municipal composting plant of Dangjin-Gun (Korea), bioaerosol levels were present at concentrations of 1.1 104 cfu/m3 (Park et al., 2011). Previous to the monitoring study whose results are presented here, we also performed an industrial hygiene study to evaluate the potential exposure of workers to the same microbiological pollutants (Nadal et al., 2009). Consequently, bioaerosol levels were measured in several zones inside the Ecoparc-2. Gram-negative bacteria and A. fumigatus cultivated at 25 and 37 1C levels were notably higher than values found outdoors. With respect to VOC concentrations, a seasonal trend was observed, with higher values in cold campaigns, being winter of 2011 the campaign which showed the highest concentration
(mean: 45.7 mg/m3). It has been found out that ambient levels of VOCs may be decreased in summer (Gallego et al., 2008), partially due to their photochemical reactivity, which is increased by higher solar radiation (Ras et al., 2010). BTEX followed a similar proﬁle as that of VOCs, although inter-seasonal differences were not so remarkable. The proﬁle in the mean airborne concentrations of 19 VOCs is shown in Fig. 4. Similar to previous studies, BTEX showed the highest contribution to the total amount of VOCs, irrespective of the sampling. Notwithstanding, the concentration of benzene was clearly below the threshold value, according to the EC Air Quality Framework Directive (2000/69/EC), set at 5 mg/m3. Formaldehyde and 1,2-dichloroethane were the only compounds showing higher levels in summer (2010). However, none of them was detected in any sample of the 2011 survey. In addition, 1,3butadiene was not detected in any sampling campaign, while styrene was only above its limit of detection (0.05 mg/m3) in a single sample. VOCs are seasonally variable as a consequence of their higher reactivity due to solar radiation, temperature and conditions of instability typical in summer (Okada et al., 2012; Yoshino et al., 2012). Similar to bioaerosols, indoor levels of the same VOCs were already assessed in a previous study (Nadal et al., 2009). VOC concentrations were analogous to those reported in MBT plants with a similar waste treatment process, such as Ecoparc-1 (Barcelona, Catalonia, Spain) (Gallego et al., 2012), and clearly higher than outdoor values. In order to establish the potential impact of the facility on the surrounding environment, the proﬁle in the microbiological and VOC concentrations, according to the wind direction and the distance to the facility, was determined (Table 2). Total bacteria and fungi grown at 25 1C showed signiﬁcant higher concentrations in the N transect with respect to the remaining directions. No signiﬁcant differences were appreciated in the levels of the rest of biological and chemical agents. Regarding the spatial pattern, no signiﬁcant differences were observed for most of the microbiological pollutants. Only fungi at 37 1C showed some signiﬁcant increases in points located near the Ecoparc-2 (300 m and 600 m) in comparison to those at farther distances (900 m). Consequently, the waste treatment facility could have a slight, but positive, inﬂuence on the surrounding environment, in terms of fungi at 37 1C. On the other hand, VOC (including BTEX) concentrations did not show a spatial proﬁle of concern. Because of its carcinogenic potential, special attention was paid to formaldehyde. In addition of being carcinogenic and mutagenic (Belpomme et al., 2007), formaldehyde is an irritant to the eye and upper airways, especially the nasal cavity, increasing the risk of childhood asthma, as well as nasopharyngeal and sinonasal cancer (Gilbert et al., 2006; St-Jean et al., 2012). Air mean concentration of formaldehyde was 3.45 mg/m3, ranging from undetected levels to 9.90 mg/m3. Formaldehyde was detected in all samples during the ﬁrst three campaigns, while its concentration was below the detection limit in summer of 2011 (Fig. 4). This fact was unexpected, since formaldehyde was not detected even in stack gas (o0.6 mg/m3). If data of the fourth campaign are not taken into account, summer values were higher (5.48 mg/m3 in 2010) than those observed in winter (3.33 and 4.98 mg/m3 in 2010 and 2011, respectively). A similar trend was already reported by Okada et al. (2012), when the atmospheric concentrations of VOCs were analyzed in different areas of Hyogo Prefecture, Japan, where median levels of formaldehyde ranged between 2.3 and 4.3 mg/m3. In order to evaluate the inhalation exposure to some health-based EU priority substances, Bruinen de Bruin et al. (2008) analyzed the outdoor and indoor concentrations of formaldehyde in 12 European cities: Arnhem (The Netherlands), Athens (Greece), Brussels (Belgium), Budapest (Hungary), Catania (Italy), Dublin (Ireland), Helsinki (Finland), Leipzig (Germany), Milan (Italy), Nicosia (Cyprus), Nijmegen (The Netherlands) and Thessaloniki (Greece). None of them presented mean levels higher than those observed
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Table 1 Concentrations of bioaerosols (cfu/m3) and VOCs (mg/m3) –including BTEX and formaldehyde – in air samples collected in the vicinity of an MBT plant in Montcada i Reixac (Catalonia, Spain).
Total bacteria (n¼60)
Gram negative bacteria (n ¼60)
Fungi (25 1C) (n¼ 60)
A. fumigatus (25 1C) (n¼60)
Fungi (37 1C) (n¼ 60)
A. fumigatus (37 1C) (n¼ 60)
BTEX (n¼ 12)
VOCs (n¼ 12)
Formaldehyde (n¼ 12)
Winter'10 Summer ‘10 Winter'11 Summer ‘11 Winter'10 Summer ‘10 Winter'11 Summer ‘11 Winter'10 Summer ‘10 Winter'11 Summer ‘11 Winter'10 Summer ‘10 Winter'11 Summer ‘11 Winter'10 Summer ‘10 Winter'11 Summer ‘11 Winter'10 Summer ‘10 Winter'11 Summer ‘11 Winter'10 Summer ‘10 Winter'11 Summer ‘11 Winter'10 Summer ‘10 Winter'11 Summer ‘11 Winter'10 Summer ‘10 Winter'11 Summer ‘11
160 843 454 1054 3 5 2 2 2152 1351 1577 1097 1 1 ND 1 60 712 61 106 21 3 ND ND 12.9 9.15 28.4 7.62 32.4 15.7 45.7 9.12 3.33 5.48 4.98 ND
212 1380 782 3124 4 7 2 2 3109 1781 2583 554 ND 1 ND ND 63 1440 49 62 54 5 ND ND 11.1 3.49 26.6 7.54 52.1 4.03 39.6 8.50 0.97 1.40 2.52 ND
33 65 110 40 1 1 1 1 462 656 700 670 ND 1 ND ND 24 182 30 68 1 1 ND ND 6.82 7.45 13.4 2.75 10.3 13.4 16.9 3.17 2.58 5.25 2.75 ND
77 136 185 70 ND 4 1 1 792 760 995 945 ND 1 ND ND 45 266 50 100 ND ND ND ND 9.81 8.81 20.0 4.89 14.4 15.5 27.0 5.44 3.15 5.80 5.20 ND
126 818 363 195 2 6 3 3 2301 1085 1300 1345 ND 1 ND ND 67 449 73 133 5 2 ND ND 13.4 10.7 35.0 9.06 21.6 18.6 62.3 13.2 3.98 6.03 5.93 ND
83 250 206 104 2 3 2 1 1126 863 1034 977 1 1 1 1 41 332 42 84 3 2 1 1 9.88 8.49 18.9 5.37 18.3 15.2 30.7 6.3 3.21 5.29 4.39 1
18–608 44–4452 10–3520 1–12590 ND-15 ND-27 1–10 1–10 340–11118 216–6756 270–12590 350–2500 ND ND-1 ND ND 8–244 114–5256 1–210 1–360 ND-185 ND-15 ND ND 3.08–43.0 3.30–16.3 2.31–100 1.68–28.5 7.08–193 8.12–21.3 4.55–121 1.84–30.0 2.00–5.20 2.60–7.90 1.90–9.90 ND
BTEX: benzene, ethylbenzene, toluene, and o-, m-, and p-xylenes, VOCs: volatile organic compounds n: number of samples collected in each campaign. ND: not detected (o LOQ). SD: standard deviation; Q1: ﬁrst quartile; Q3: third quartile. a
For the calculation of the geometric mean, zero values were converted to the unity (0 ¼ 1).
outdoor for the Ecoparc-2 in summer, with concentrations ranging 0.4–4.9 mg/m3. Similarly, the mean concentration of formaldehyde in 40 outdoor samples from Rome (Italy) was found to be 2.75 mg/ m3 (Santarsiero and Fuselli, 2008), while the mean air levels in a residential area in Hagfors (Sweden) was 3.7 mg/m3 (Gustafson et al., 2007). Recently, Villanueva et al. (2013) tested in the ﬁeld the suitability of the Analysts passive sampler for the determination of formaldehyde and acetaldehyde in indoor and outdoor ambient air in Ciudad Real (Spain). They reported concentrations of formaldehyde between 2.2 and 3.1 mg/m3 (Villanueva et al., 2013), which are clearly lower than those found in Montcada i Reixac. Although indoor levels are generally higher than those found outdoor (Kim et al., 2013), formaldehyde is considered to be a chemical of concern at levels exceeding 1 mg/m3, a concentration more or less corresponding to background levels in rural areas (Pegas et al., 2011). A number of scientiﬁc studies have reported levels of VOCs in ambient air. Ramírez et al. (2012) analyzed a total of 86 VOCs in three different locations around a chemical/petrochemical industrial zone in Tarragona (Spain). The highest maximum concentrations of toluene, ethylbenzene, and 1,2,3-trimethylbenzene (26.2, 14.3, and 18.6 mg/m3, respectively) were found near a chemical area, while the highest levels of methylene chloride were detected in a background suburban area (129.7 mg/m3). Thepanondh et al. (2010) determined the annual levels of some ambient VOCs in the vicinity of a petrochemical industrial complex in the Maptaput district (Thailand), reporting ranges of 1.42–4.78, 0.10–0.57,
0–0.20, 0.30–21.3, 0–0.48, and 0.10–0.48 mg/m3 for benzene, 1,3-butadiene, methylene chloride, 1,2-dichloroethane, tetrachloroethylene, and trichloroethylene, respectively. In general terms, the concentrations of VOCs around the MBT plant assessed here fell within the lowest part of the range in comparison to those found in petrochemical areas (Thepanondh et al., 2010; Ramírez et al., 2012). In addition, the proﬁle was very similar to that reported by Civan et al. (2011), who analyzed VOCs by means of passive sampling devices in Bursa, one of the most heavily industrialized cities in Turkey. These authors found that toluene was the most abundant VOC found at all sites, with a median concentration ranging from 0.99 mg/m3 in background samples to 35.98 mg/m3 at industrial sites, followed by m-, p-xylene and ethylbenzene. We also analyzed the concentrations of the same target VOCs here studied in the surroundings of an MSW incinerator in Tarragona County (Catalonia, Spain), prior to the construction of an MBT plant (Vilavert et al., 2009, 2011). Despite this facility has not been built yet, data were used to assess the environmental burdens of VOCs near an incineration plant, a kind of facility for which there is a notable lack of information concerning the impact and the health risks, associated with environmental pollutants other than polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) and heavy metals (Vilavert et al., 2011). The concentrations of BTEX ranged from 6.3 to 17.0 mg/m3, while the same 19 VOCs studied here showed mean levels within the range
L. Vilavert et al. / Environmental Research 133 (2014) 27–35
5.0 0.0 Summer'10
b b a
b 1000 500
Fig. 3. Mean concentrations of bioaerosols (cfu/m ) and VOCs (μg/m ) – including BTEX and formaldehyde – during four sampling campaigns. Seasonal and temporal variations. a,b,c Different superscripts indicate signiﬁcant differences at p o0.05. ND: Not detected.
7.6–18.2 mg/m3. BTEX values near the Ecoparc-2 of Montcada i Reixac are very similar to those found near the MSW incinerator. However, it must be highlighted that formaldehyde was not detected in any of the 64 samples, collected in the course of four sampling campaigns. This could be indicative that MBT plants may have a higher inﬂuence on the state of pollution, at least concerning the presence of formaldehyde, whose exposure may mean noncancer and cancer effects for the respiratory system. The possible synergistic interactions of formaldehyde with acrolein or acetaldehyde have been suggested as potentially signiﬁcant in the increase of respiratory risks (Logue et al., 2010). 3.2. Human health risk assessment Monitoring data were used to assess the non-carcinogenic and carcinogenic risks due to human exposure of VOCs. Several working scenarios were considered, with special emphasis on seasonal differences: (a) winter, (b) summer, and (c) all. Risks were individually determined for each pollutant, while the total risk was calculated as the sum of the individual risks. In terms of noncarcinogenic risk, formaldehyde and trichloroethylene presented the greatest contribution to the Hazard Quotient (48% and 28%, respectively), when considering the whole database (Table 3). Certain seasonal inﬂuence was observed, as non-cancer risks of
VOC exposure were notably higher in winter. This would be linked to the higher exposure to trichloroethylene in the cold season. It must be remarked that the RfCi of this compound has not been established by US EPA until recently. In any case, the overall Hazard Index exceeded the threshold value, set at the unity in winter. In the other two scenarios (when grouping the total number of samples (n ¼48) and in summer), values of noncancer risks were also close to the maximum recommended value. On the other hand, cancer risk was evaluated for those chemicals for which IUR values have been set, such as benzene, ethylbenzene, naphthalene, methylene chloride, 1,2-dichlorethane, chloroforme, trichloroethylene, tetrachloroethylene, 1,3-butadiene, and formaldehyde. The latter was identiﬁed as the compound presenting the higher cancer risk, with values in all the scenarios above 10 5, which is the acceptable value of cancer risk (1/100,000 for lifetime-exposed individuals) according to the Spanish legislation (Ministerio de Medio Ambiente, 2007). When considering the overall cancer risks, from a cumulative perspective, the total risks also exceeded 10 5. Although risk values between 10 6 and 10 4 are considered as acceptable by US EPA (1989), there is no consensus yet on the acceptable lifetime risks derived from exposure to carcinogenic chemicals. Okada et al. (2012) reported similar ﬁndings in different locations of Japan, where excess cancer incidences for formaldehyde exceeded 10 5. In contrast,
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Benzene Toluene Ethylbenzene m,p-Xylene o-Xylene Styrene Naphthalene Methylene Chloride 1,2-Dichloroethane Chloroforme Trichloroethylene Tetrachloroethylene 1,3-Butadiene 1,3,5-Trimethylbenzene 1,2,4-Trimethylbenzene Summer '11
µg/m3 Fig. 4. Proﬁle of VOCs (mean values) in air samples collected in the surroundings of an MBT plant in Montcada i Reixac (Catalonia, Spain). Table 2 Mean concentrations of microbiological pollutants (cfu/m3) and VOCs (mg/m3) according to the direction and distance to the MBT plant. Wind direction Number of samples Total bacteria Gram-negative bacteria Fungi 251 C A. fumigatus 251 C Fungi 371 C A. fumigatus 371 C VOCs BTEX Formaldehyde
(n¼60) (n¼60) (n¼60) (n¼60) (n¼60) (n¼60) (n¼12) (n¼12) (n¼12)
1689a ND 176 2 15.5 9.59 2.93
1029b ND 95 ND 14.4 9.62 3.58
829bc ND 154 15 40.0 13.1 3.60
746c ND 97 4 32.9 25.7 3.69
Number of samples
(n¼80) (n¼80) (n¼80) (n¼80) (n¼80) (n¼80) (n¼16) (n¼16) (n¼16)
508 3 1149
306 3 1116
315 2 929
ND 170a 12 32.8 11.9 3.41
ND 125a 4 21.8 16.1 3.34
ND 98b 1 22.5 15.6 3.61
a,b,c Different superscripts indicate signiﬁcant differences at p o 0.05. ND: Not detected.
Table 3 Non-carcinogenic and carcinogenic risks of exposure to VOCs for different scenarios near an MBT plant (Montcada i Reixac, Catalonia, Spain). Non-carcinogenic risks
Benzene Toluene Ethylbenzene m,p-Xylene o-Xylene Styrene Naphthalene Methylene chloride 1,2-Dichloroethane Chloroforme Trichloroethylene Tetrachloroethylene 1,3-Butadiene 1,3,5-Trimethylbenzene 1,2,4-Trimethylbenzene p-Isopropyltoluene n-Propylbenzene Isopropylbenzene Formaldehyde Total riskn n
4.0E-02 1.7E-03 2.0E-03 6.8E-02 1.4E-02 2.0E-06 9.1E-03 ND 1.2E-02 1.4E-03 4.2E-01 3.5E-02 ND 4.1E-02 1.1E-01 – 1.1E-04 – 4.1E-01 1.17
9.4E-03 8.7E-04 7.4E-04 2.1E-02 5.6E-03 ND 6.7E-04 ND 1.3E-02 ND 9.5E-01 ND ND 1.8E-02 4.8E-02 – 6.2E-05 – 5.4E-01 0.75
2.5E-02 1.3E-03 1.4E-03 4.4E-02 9.9E-03 1.0E-06 4.9E-03 ND 1.2E-02 6.9E-04 2.6E-01 1.8E-02 ND 3.0E-02 8.1E-02 – 8.4E-05 – 4.5E-01 0.94
4.0E-06 – 2.1E-06 – – – 4.0E-07 ND 9.2E-07 1.3E-06 1.5E-06 1.6E-07 ND – – – – – 2.2E-05 3.27E-05
9.4E-07 – 8.0E-07 – – – 2.9E-08 ND 1.0E-06 ND 3.3E-07 ND ND – – – – – 2.9E-05 3.24E-05
2.5E-06 – 1.5E-06 – – – 2.1E-07 ND 9.7E-07 6.7E-07 9.1E-07 7.9E-08 ND – – – – – 2.5E-05 3.14E-05
Total risk as a sum of individual risks for each compound. ND: Not detected.
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Vilavert et al. (2011) found lower values in the Hazard Index and the total cancer risk with respect to the levels of concern (1 and 10 5, respectively), when evaluating the non-occupational exposure to VOCs near a MSW incinerator in Catalonia. Furthermore, they were clearly lower than outdoor values found in the surroundings of the Ecoparc-2. It could indicate that, in comparison to waste incineration plants, municipal waste organic fraction treatment plants have a higher impact on the environment related to the presence of VOCs. Furthermore, health risks derived from inhalation of VOCs, and particularly formaldehyde, exceeded the level of concern.
4. Conclusions The results of a 2-year follow-up program of the environmental impact of Ecoparc-2 are presented here, focusing on the potential release of VOCs and bioaerosols. Notable ﬂuctuations in the levels of microbiological agents were found, with seasonal trends for total bacteria and fungi. In turn, VOC concentrations were slightly higher in winter, being similar to or even lower than those reported in the scientiﬁc literature. However, formaldehyde was an exception, with mean air levels in one of the sampling campaigns being even higher than those found in urban areas worldwide. Furthermore, the occurrence of formaldehyde in air was related to higher health risks for the population living near the MBT plant, since the estimated non-cancer and carcinogenic risk values exceeded the respective threshold levels. In conclusion, based on the results of the present study, special attention to airborne formaldehyde should be paid in the surroundings of MBT plants, in order to assure that the current exposure to this compound is not affecting the health of the population living in the neighborhood.
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