Bio: Dr Ann Olsson is epidemiologist and leader of the Occupational Cancer Epidemiology Team in the Environment and Lifestyle Epidemiology Branch at IARC in Lyon, France. She conducts studies and coordinates secondary analyses investigating occupational exposures in relation to various cancers worldwide. Dr Olsson obtained her PhD at Karolinska Institutet in Stockholm, Sweden 2010, and has published >80 scientific articles in renowned journals

Abstract: Arsenic, beryllium, cadmium, chromium VI, and nickel are classified as carcinogenic to humans, in Group 1, by the IARC Monographs Program. Yet, further research is needed to characterize effects of those carcinogens including exposure–response relationships and joint effects with other exposures (e.g. tobacco smoking), and in relation to other cancer types. We analysed case-control data from SYNERGY - 14 pooled studies from Europe and Canada including 16 900 lung-cancer cases and 20 965 control subjects; NORD-TEST - a registry-based study in the Nordic countries comprising 11 500 testicular germ cell tumours (TGCT) and 40 000 population controls; TESTIS – a French nationwide study including 454 TGCT cases and 670 controls; and the Childhood Cancer and Leukaemia International Consortium with approximately 30 000 children with leukaemia (cases) and 2 330 000 children without leukaemia. Retrospective occupational exposures were assigned to subjects via job-exposure matrices. SYNERGY showed that relatively low cumulative levels of occupational exposure to Cr(VI) and nickel were associated with increased ORs for lung cancer, particularly in men. Joint effects of Cr(VI) and nickel with smoking were greater than additive, but not different from multiplicative. NORD-TEST showed increased risk of TGCT in the sons of fathers exposure to high levels of Cr(VI) around conception, while TESTIS did not confirm this results. TESTIS showed however an association with TGCT for the subject’s own occupational exposure to heavy metals, although difficult to distinguish the effects of single heavy metals. CLIC showed no significant risks for parental occupational exposure to heavy metals although slightly elevated ORs. Epidemiological studies show that heavy metals are associated with increased risks of lung cancer and TGCT, but it is challenging to interpret the results because of high correlations between heavy metals and/or solvents. Therefore, toxicological studies are complementary and needed to understand the underlying mechanisms of carcinogenicity.