Impact of fine particulate matter exposure on breast cancer mortality: A county-level analysis in the United States.

Abstract

e13169 Background: Fine particulate matter (PM2.5) air pollution is a known environmental risk factor for various health outcomes, including cancer. Breast cancer (BC) remains a leading cause of cancer mortality in the U.S., with environmental factors like air pollution potentially contributing to mortality. This study examines the association between fine PM2.5 exposure and BC mortality rates, stratified by average-onset (aoBC [≥50 years at diagnosis]) and early-onset (eoBC [ < 50 years at diagnosis]) cases. Methods: Age-adjusted county BC mortality data (1999–2020, n = 2890 counties) were obtained from CDC Underlying Cause of Death (ICD-10: C50), while 1999-2019 PM2.5 estimates (ug/m3), derived from Atmospheric Composition Analysis Group data, were mapped to U.S. county boundaries using R v.4.3.2. Covariates were derived from Census American Community Survey (ACS) 5-year estimates, CDC data, and County Health Rankings (CHR) data and included county-level area deprivation index (ACS), non-Hispanic Black % (ACS), Hispanic % (ACS), obesity prevalence (CDC), smoking prevalence (CHR), binge alcohol consumption (CHR), and uninsured % (ACS). Negative binomial count models were fit to explore associations between PM2.5 and BC mortality rates, adjusted for covariates. Deviance R 2 was computed to examine model fits. Results: We found that for every 1% increase in PM2.5 exposure, aoBC mortality increased by 0.25% (p = 0.086) and eoBC mortality increased by 0.75% (p = 0.006), after adjustment for covariates. Deviance R 2 values indicated that PM2.5 and covariates explained 21.6% and 33.1% of the deviance in aoBC and eoBC mortality, respectively. Conclusions: PM2.5 exposure was a significant predictor of BC mortality, but only for eoBC cases. Air pollution and other covariates accounted for roughly one-third of the county-level deviance, suggesting the influence of additional factors. Systemic and individual-level interventions to reduce air pollution exposure may mitigate BC mortality disparities in younger populations. Further studies are needed to explore other potential contributors to BC mortality.