Residential proximity to dioxin-emitting facilities and risk of non-Hodgkin lymphoma in the NIH-AARP Diet and Health Study

Abstract

TPS 761: Health effects of pollution sources and components, Johan Friso Foyer, Floor 1, August 28, 2019, 3:00 PM - 4:30 PM Background: Polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) are persistent organic pollutants emitted from industrial combustion facilities and various manufacturing processes. Residential proximity to facilities emitting PCDD/Fs has been associated with increased PCDD/F levels in homes and risk of non-Hodgkin lymphoma (NHL), though few studies have investigated these relationships. Methods: We evaluated associations between residential proximity to dioxin-emitting facilities and NHL among participants of the NIH-AARP Diet and Health Study, a prospective cohort (N=548,845) in 6 states and 2 cities in the U.S. We linked geocoded enrollment addresses (1995-1996) with a U.S. Environmental Protection Agency database of 4,478 historical PCDD/F sources, which contained toxic equivalency quotient (TEQ) emissions estimates from 1995. We evaluated NHL risk with proximity metrics indicating presence/absence of one or more facilities within 3 or 5-km of participant homes, overall and separately by facility type (e.g. coal-fired power plants, municipal solid waste incinerators). We also examined risk by exposure intensity within 5km using a distance- and toxicity-weighted average emissions index (AEI [ng TEQ/km2]). Cox regression was used to estimate associations (hazard ratio, HR; 95% confidence interval, 95%CI) with NHL and major subtypes, adjusting for demographic, lifestyle, and dietary characteristics. Results: With 6,747 incident cases through 2011, we found no associations between overall or facility-specific PCDD/F proximity metrics and risk of NHL or major subtypes. However, participants with an AEI >95th percentile had significantly increased risk of developing NHL compared to unexposed participants (HR=1.27; 95%CI=1.05-1.53; p-trend=0.01). Risk of follicular lymphoma was also significantly elevated among participants with the highest quartile of the AEI (HR=1.33; 95%CI=1.02-1.74; p-trend=0.04). We saw no significant associations with other NHL subtypes. Conclusions: Using exposure metrics that accounted for distance and the toxicity of emissions, we found evidence of an association between residential exposure to high PCDD/F and risk of NHL overall and follicular lymphoma in particular.