O-182 The association between the incidence of postmenopausal breast cancer and occupational exposure to selected organic solvents in Montréal

Abstract

from the electoral list for Montreal, and frequency-matched to cases using 5-year age groups. We elicited information on occupational history and potential risk factors. An occupational hygienist coded all jobs to the International Standard Classification of Occupations 1988 (ISCO88); these occupation codes were linked to an ELF-MF job exposure matrix (JEM) to obtain mean workday-average ELF-MF exposure. Logistic regression was used to estimate odds ratios (OR) and 95% confidence intervals (CI) for incident breast cancer and past ELF-MF cumulative exposure (CE) and average exposure (AE), adjusting for individual-level and ecological covariates. Separate analyses were conducted restricting exposure before the first full-term pregnancy or age 35 for women who were never pregnant and for hormonal receptor phenotypes.Results We recruited 592 controls and 663 cases. The fully adjusted ORs per increase in the interquartile range (IQR=2.12 mT-years) of CE was 0.99 (95% CI: 0.94-1.06) and for AE (IQR=1.54 mT) was 0.96 (95% CI: 0.90-1.02). The associations between breast cancer and ELF-MF CE and AE were consistent with linearity. Adjustments for various combinations of potential confounders did not change these patterns. We found no evidence of associations for different breast cancer subtypes or exposure before the first full-term pregnancy or the age of 35. Conclusions Our findings suggest that occupational exposure to ELF-MF, assigned here using a JEM, may not be associated with the risk of incident postmenopausal breast cancer.