| There is evidence that ionizing radiation, polycyclic aromatic hydrocarbons, and environmental tobacco smoke have been hypothesized to affect breast cancer risk. There is also evidence that early life exposures may be important in the etiology of this disease. Nevertheless, the role that exposure to environmental pollutants and the timing of that exposure plays in the etiology of breast cancer remains unclear. A population-based, case-control study was conducted to investigate residential proximity to radiologically contaminated industrial sites and exposure to environmental tobacco smoke and polycyclic aromatic hydrocarbons and the risk of breast cancer. Cases included 1,166 women aged 35–79 years diagnosed between the years 1996 and 2001 with histologically-confirmed, primary, incident breast cancer. Controls (n = 2,105) were randomly selected from the New York State Department of Motor Vehicles list and the Healthcare Financing Administration Medicare rolls. Logistic regression was used to calculate odds ratios (OR) and 95% confidence intervals (95% CI). Proximity (<3.3 km) to radiologically contaminated industrial sites was suggestive of a slight increase in risk (adjusted OR = 1.69, 95% CI = 0.68–4.21) for premenopausal women. The presence of household smokers at the birth address was associated with a slight increase in risk (OR = 1.34, 95% CI = 0.77–2.32), but not for postmenopausal women (OR = 1.02, 95% CI = 0.68–1.55). Exposure to high concentrations of total suspended particulates (TSP) (>140 μg/m 3) at birth was associated with an increase in risk (OR = 3.06, 95% CI = 1.13–8.28) compared with those exposed to low concentrations (<84 μg/m 3) for postmenopausal women. The results of these analyses suggest that environmental exposure to TSP and environmental tobacco smoke in early life may play a role in the etiology of breast cancer. Conversely, residential proximity at the time of birth to radiologically contaminated industrial sites was weakly associated with the breast cancer risk, although this association was not related to radiological contamination. These findings are provocative; however, further research is needed to corroborate the results and gene-environment interaction studies may be particularly useful in elucidating whether PAHs in air pollution and environmental tobacco smoke are important in the etiology of breast cancer. |
