White AJ, et al. – In this first-in-kind study, researchers assessed the relationship between air toxics, breast density, and breast cancer. The study sample consisted of 222,581 participants who had a screening mammogram in 2011 at a radiology facility in the Breast Cancer Surveillance Consortium. The investigators used the 2011 EPA National Air Toxics Assessment to determine zip code residential levels of airborne polycyclic aromatic hydrocarbons (PAHs) and metals (arsenic, cadmium, chromium, cobalt, lead, manganese, mercury, nickel, and selenium). The Breast Imaging–Reporting and Data System was used to determine breast density. According to findings, greater residential levels of arsenic, cobalt, lead, manganese, nickel, or PAHs were individually linked to breast density. Women living in areas with higher levels of lead and cobalt were more likely to have dense breasts, which has been strongly associated with breast cancer.