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Archives of Environmental Health: An International Journal Publication details, including instructions for authors and subscription information: http://www.tandfonline.com/loi/vzeh20
How Many Cancers are Attributable to Occupational Exposures? L. Tomatis M.D.
International Agency for Research on Cancer , Lyon, France Published online: 03 Aug 2010.
To cite this article: L. Tomatis M.D. (1991) How Many Cancers are Attributable to Occupational Exposures?, Archives of Environmental Health: An International Journal, 46:1, 5-5, DOI: 10.1080/00039896.1991.9937422 To link to this article: http://dx.doi.org/10.1080/00039896.1991.9937422
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How Many Cancers Are Attributable to Occupational Exposures? OCCUPATIONAL carcinogens were among the first human carcinogens to be identified, and largely because of them, the causal relationship between environmental exposures and human cancer has been established. The work environment offered the ideal situation in which to observe a causal relationship between a given environmental agent and an increased risk of cancer: exposure levels to known chemical agents or to complex chemical mixtures were high or very high, the duration of exposure was long, and the individuals exposed were relatively easily identifiable. Among some of these groups, cancer occurred with such frequency that it could not escape the attention of some alert physicians and epidemiologists. Occupational cancer cases have been particularly easy to trace when they occur during work years. Rarely have attempts been made to relate cancer that occurs during old age in retired individuals to a particular occupational exposure. Accurate occupational history of old people is rarely made because data may not be obtained easily. This may be why, in industrialized countries, many fewer (hundreds instead of thousands) annual cancer cases than expected (even following the most conservative estimate of the proportion of occupational cancers of the total cancer cases) have been compensated as being the result of occupational exposure. It i s hoped that the investigation of Vineis and Simonato' may, among other things, contribute to avoiding the perpetuation of this residual social injust ice. The approach taken by Vineis and Simonato in evaluating the proportion of cancer cases attributable to occupation, at least for cancers of the lung and bladder (between 1O h and 40% for the lung and 0-2% and 24% for the bladder), will assist in clarifying the proportions of occupational cancers, which have varied by an order of magnitude or more. Their study shows that the proportion of cases attributable to occupational hazards is determined by the prevalence of exposed individuals within the general population and, in any given study, by the proportion of individuals actually exposed within the group considered. This may seem an obvious conclusion, but it has, in fact, been the origin of a continuous misunderstanding. The observations of Vineis and Simonato also show that the variations in relative risks observed in different
studies very likely depend on the different levels of exposure that may have occurred for a particular type of occupation, in different countries, or in different factories within the same country. The criteria used to assess exposures, although much improved since the first early investigations of occupational cancer, remain disomogeneous and are not always defined precisely and may still be at the origin of miscalculations. It should not be overlooked that current occupational exposures may be at the origin of elevated risks. Even though a lower proportion of the general population is exposed today than was exposed decades ago, it can not be assumed that the risk for the fraction of the p o p ulation actually exposed has decreased or is necessarily low. This may not be true, e.g., in workers of develop ing countries where some "dirty" operations have been shifted from industrial countries. One may hope that the work of Vineis and Simonato will, directly or indirectly, contribute to the clarification of two of the most debated issues today: (1) the effect of low doses of exposure to carcinogens and (2) the possible interaction between multiple low-dose exposures. Whereas in recent years certain specific occupational exposures have decreased in number and intensity, as have the total number of individuals exposed because of their work, the exposure of the general population to environmental carcinogens has, if anything, increased. We should at least not forget that chemicals identified as human carcinogens in a work environment do not cease to be carcinogenic because the exposure to them is not occupational (in a similar way as tobacco smoke does not cease to be carcinogenic when it is inhaled passively). In this sense, the term "occupational carcinogens" may be misleading and could perhaps be replaced by the term "carcinogens of industrial origin." Reference
L. Proportion of lung and bladder cancers males due to occupation: a systematic approach. Arch Environ Health 1991; 46(1):6-15.
1 . Vineis P, Simonato
1. Tomatis, M.D. Director International Agency for Research on Cancer Lyon, France 5