Occupational exposure to unintentionally emitted nanoscale particles and risk of cancer: from lung to central nervous system - results from three French case-control studies

ABSTRACT Objectives Nanoscale particles (1-100 nm) can be of natural origin, and either intentionally or unintentionally produced by human activities. Toxicological data have suggested a possible carcinogenic effect of such particles. The aim of this study was to estimate the association between occupational exposure to nanoscale particles and risk of lung cancer, pleural mesothelioma and brain tumors in adults. Methods Three French population-based case-control studies were analyzed: 1) the ICARE study including 2,029 lung cancer cases and 2,591 controls; 2) the PNSM study including 371 pleural mesothelioma cases and 730 controls and 3) the CERENAT study including 257 brain tumor cases and 511 controls. Occupational exposure to unintentionally emitted nanoscale particles (UNPs) was retrospectively assessed by a job exposure matrix providing a probability and a frequency of exposure. Results In adjusted analyses among men, significant associations between occupational exposure to UNPs and lung cancer (OR=1.51; 95% CI: 1.22-1.86 and brain tumors (OR=1.69; 95% CI: 1.17-2.44) were observed. No increased OR was observed for pleural mesothelioma (OR=0.78; 95% CI: 0.46-1.33). Conclusion This is the first study showing positive associations between occupational exposure to UNPs and increased risk of lung cancer and brain tumors. These preliminary results should encourage further epidemiological research.