Residential Proximity to Dioxin-emitting Facilities and Risk of Non-Hodgkin Lymphoma in the NIH-AARP Diet and Health Study.

Purpose: Few studies have investigated the relationship between risk of non-Hodgkin lymphoma (NHL) and residential proximity to polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/F) emitted from industrial combustion and manufacturing sources. Methods: We evaluated this relationship 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. Exposure metrics indicated presence/absence of any facility within 3 and 5km of participant homes, overall and by type of facility (e.g., coal-fired power plants, waste incinerators), which vary in emissions levels and constituency. We also calculated exposure as a distance- and toxicity-weighted average emissions index (AEI [g TEQ]). We used Cox regression to estimate associations (hazard ratios; HR and 95% confidence intervals; CI) with NHL and major subtypes, adjusting for and by strata of sociodemographic and lifestyle characteristics. Results: With 6,747 incident cases through 2011, we found no association between living near any or specific types of PCDD/F-emitting facilities and NHL risk. However, participants with an AEI >95th percentile within 5km had increased risk of NHL compared to unexposed (HR = 1.28; CI = 1.05-1.55; p-trend = 0.01). Specifically, we observed increased risk for lymphoplasmacytic lymphoma (HR = 2.98, CI = 1.16-7.63; p-trend = 0.03) and diffuse large B-cell lymphoma (HR = 1.65, CI = 1.11-2.46; p-trend = 0.01). Non-Hispanic blacks were nearly three times as likely as whites to live <5 km of a facility, although we had limited power to evaluate heterogeneity in associations by race/ethnicity. Associations did not vary by age, smoking status, body mass index, or urbanicity of residence. Conclusions: Using an exposure metric accounting for distance and the toxicity of emissions, we found significant positive associations between residential exposure to high PCDD/F emissions and risk of NHL and two subtypes. Our results underscore the hazard for populations living near sources of these persistent organic pollutants. [ABSTRACT FROM AUTHOR]