Residential Proximity to Superfund Sites: Associations with Sociodemographic Characteristics and Breast Cancer

Background: Superfund sites are hazardous waste sites that have uncontrolled releases of chemicals, including known carcinogens. Residential proximity to these sites is not equitably distributed and sociodemographic characteristics associated with proximity beyond race are not well described. Additionally, research is lacking with regard to breast cancer risk associated with living near sites emitting chemicals that may be carcinogens.Methods: We obtained data from Superfund sites active in 2000 and linked it to US Census data from 2000. Superfund sites with similar contaminant profiles were identified using latent class analysis. Census tract centroids located within 3 miles of every Superfund site were identified and a weighted average of the tract-level demographics were calculated. We compared median sociodemographic characteristics by Superfund latent class. Separately, we linked the Superfund data to NIEHS Sister Study participant data to assess the association between residential proximity to Superfund sites and breast cancer. The NIEHS Sister Study is a nationwide prospective cohort of women ages 35-74 in the US, recruited from 2003-2009, who had at least 1 sister diagnosed with breast cancer but no personal breast cancer history at the time of enrollment.Results: Aim 1 identified 7 latent classes based on 12 contaminant categories from 1,332 Superfund sites active in 2000. Overall, there were few differences in sociodemographic characteristics observed by presence of any Superfund site compared to the overall US census. Upon stratifying by latent class, evidence of disparities emerged for two classes of sites that were more likely to be near communities with higher proportions of non-white individuals, lower socioeconomic status and higher social vulnerability. Aim 2 observed few associations between exposure to a single Superfund site and breast cancer. Including exposure to multiple sites and stratifying by latent class and contaminant category identified weak associations with breast cancer.