br C Marant Micallef et al International
C. Marant Micallef et al. International Journal of Hygiene and Environmental Health 222 (2019) 22–29
Occupational exposures to certain chemical, physical, biological agents and occupational circumstances (e.g. rubber manufacturing in-dustry) are well established risk factors for the development of cancer (Pearce et al., 2015; Siemiatycki et al., 2004). However, still today we observe a large number of carcinogenic agents across various occupa-tional settings. Therefore, up-to-date data on the prevalence of exposure to occupational carcinogens and the cancer cases attributable to these agents are vital information for policy makers for the formulation, prioritization and implementation of targeted prevention strategies to improve working conditions by reducing exposure and ultimately re-duce the cancers attributable to these carcinogens (Rushton et al., 2007).
Previous studies have estimated that approximately 3%–14% and
0%–2% of all new cancer cases among men and women respectively are attributable to occupational exposures in high-income countries (Boﬀetta et al., 2010; Driscoll et al., 2005; Fritschi and Driscoll, 2006; Nurminen and Karjalainen, 2001; Rushton et al., 2010; Steenland et al., 2003). In France 2.3% and 0.3% of all new cancer cases in 2000 among men and women respectively were attributable to occupational ex-posures; however, this estimate was based on cross-sectional prevalence estimates of exposure from the mid-1990s, and included only selected occupational agents (Boﬀetta et al., 2010). Furthermore, the most re-cent estimates from the French National Public Health Agency in 2012, which adjusted for changes in the prevalence of exposure over time, were limited to four Group 1 exposures (asbestos, benzene, tri-chloroethylene and Cell Counting Kit-8 dust) (Gilg Soit Ilg et al., 2016).
Accordingly, the objective of this study was to estimate the number of new cancer cases in France in 2015 attributable to historical ex-posure to occupational carcinogens with suﬃcient evidence of a causal relationship with cancer risk in humans (Group 1, as classified by the International Agency for Research on Cancer (IARC)), adjusting for changes in exposure over time. A secondary analysis provides similar estimates, including all Group 1 and 2A occupational carcinogens and cancer sites pairs with at least limited evidence of a causal relationship.
2. Material and methods
Data on the prevalence of occupational exposures and the relative risk (RR) of developing cancer for people ever exposed to occupational agents compared to those never exposed were combined to estimate the Population-Attributable Fraction (PAF) (Shield et al., 2016). Subse-quently, the number of new cancer cases attributable to occupational exposures was estimated by applying the PAFs to the estimated new cancer cases in France in 2015.
2.1. Exposures and cancers included
We considered occupational agents classified as carcinogenic (Group 1 of IARC Monographs) or probably carcinogenic to humans (Group 2A of IARC Monographs). To account for diﬀerences in the level of evidence across exposure/cancer site pairs, the main analysis in-cluded only Group 1 occupational agent and cancer site pairs with suﬃcient evidence of a causal relationship as determined by the IARC Monographs program volumes 1 to 114 (International Agency for Research on Cancer, 2017; Pearce et al. 2015), whereas the secondary analysis included all Group 1 and Group 2A occupational agent and cancer site pairs with at least limited evidence of a causal relationship. Furthermore, only those occupational exposures which were relevant for France, where exposure data were available, and where an RR es-timate was available were included in the study (Marant Micallef et al., 2018). Based on these criteria, 25 agents were included in the main analysis, with these agents causally related to the development of 23 cancer sites, representing 44 occupational agent and cancer site pairs (see Figure S1) (Marant Micallef et al., 2018). Furthermore, the
secondary analysis included 34 agents which were causally related to 23 cancers, representing 73 occupational agent and cancer site pairs.
2.2. Estimation of the proportion of the population ever exposed to occupational carcinogens
We used multiple sources of occupational exposure data in order to derive the most comprehensive data which are outlined in Table 1. Briefly, we used the French national survey on occupational exposures among 50,000 employees (SUMER), the French CAREX estimates, the national labor force survey, a French agricultural cohort (AGRICAN), the national monitoring system for workers exposed to ionizing radia-tion (SISERI), and the Matgéné program combining lifetime self-re-ported job history of a representative sample of 10,000 French persons with a French-specific job-exposure matrix (JEM).