Association between hospital discharge rate for female breast cancer and residence in a zip code containing hazardous waste sites.

Background: Exposure to chemicals plays a role in risk of breast cancer. However, possible associations between risk of breast cancer and residential proximity to hazardous waste sites (HWSs) have not been reported.

Methods: We determined rates of hospital discharge with a diagnosis of female breast cancer in relation to residence in a zip code containing HWSs in New York State (NYS) after adjustment for ethnicity, age, income and urbanicity. Waste exposure was assessed by both the number of waste sites and the type of contaminants. Negative binomial regression was used to test the associations.

Results: After controlling for confounders, the hospital discharge rate of breast cancer for women living in zip codes having four or more HWSs or in zip codes having one HWS increased significantly (at the 0.05 level) by 9.1% and 6.4%, as compared to those living in a zip code with no HWS. The association for women living in zip codes having two or three HWSs was not significant. This indicates that the extent of exposure cannot be assessed solely by the number of waste sites. The discharge rate for women living in zip codes containing at least one volatile organic compound (VOC) waste site was significantly increased 5.6% as compared to those living in a zip code without any HWS, while the increases were not significant for women living in zip codes containing waste sites with persistent organic pollutants (POPs) or other contaminants. The significant associations were stronger for African American than Caucasian women and stronger in more urbanized than in rural areas.

Conclusions: Residence within a geographic area (defined by zip codes) that includes a hazardous waste site with VOCs is significantly associated with an increased rate of hospitalization for breast cancer, and the association is stronger for African American than Caucasian women and stronger in more urbanized than in rural areas after adjustment for the confounders.