Women's occupational exposure to polycyclic aromatic hydrocarbons and risk of breast cancer.

OBJECTIVE: To estimate the association between occupational polycyclic aromatic hydrocarbon (PAH) exposure and female breast cancer.
METHODS: Lifetime work histories for 1130 cases and 1169 controls from British Columbia and Ontario (Canada) were assessed for PAH exposure using a job-exposure matrix based on compliance measurements obtained during US Occupational Safety and Health Administration workplace safety inspections.
RESULTS: Exposure to any level of PAHs was associated with an increased risk of breast cancer (OR=1.32, 95% CI: 1.10 to 1.59), as was duration at high PAH exposure (for >7.4 years: OR=1.45, 95% CI: 1.10 to 1.91; ptrend=0.01), compared with women who were never exposed. Increased risk of breast cancer was most strongly associated with prolonged duration at high occupational PAH exposure among women with a family history of breast cancer (for >7.4 years: OR=2.79, 95% CI: 1.25 to 6.24; ptrend<0.01).
CONCLUSIONS: Our study suggests that prolonged occupational exposure to PAH may increase breast cancer risk, especially among women with a family history of breast cancer. © Author(s) (or their employer(s)) 2019. No commercial re-use. See rights and permissions. Published by BMJ.