Exposure to pesticides and breast cancer in the city of Petrópolis, Brazil.

To investigate the association between pesticide use and breast cancer. A hospital-based case-control study was conducted in Petrópolis city, Brazil. The study data were obtained through interviews, and the magnitude of the association between self-reported pesticide exposure and breast cancer was determined using unconditional logistic regression. A higher estimated risk for breast cancer was found in women exposed to pesticides for 10 or more years, where this association was not statistically significant after adjusting for potential confounders (OR = 1.40; 95% CI 0.85-2.49). A positive statistically significant association was found between breast cancer and higher educational level or previous use of hormone replacement therapy (HRT), whereas having had 2 or more pregnancies to term proved a protective factor. Further studies elucidating the contribution of pesticide exposure to the development of breast cancer are needed, given that current findings in the literature are conflicting.