PM2.5 exposure and incident diabetes and hypertension: Preliminary results from the Black Women’s Health Study

Abstract

Background. Laboratory evidence suggests that fine particulate matter PM2.5 may contribute to the genesis of chronic conditions like diabetes and hypertension. Although air pollution has been associated with the prevalence of these conditions, the few epidemiologic data on its relation to incident diabetes and hypertension have been inconsistent. Aims. We assessed the association of ambient PM2.5 and incident type 2 diabetes and hypertension in the Black Women’s Health Study (BWHS), a follow-up study of African American women. Methods. BWHS participants reported incident diabetes and hypertension on biennial questionnaires from 1995-2011. We estimated long-term average PM2.5 levels at participant addresses from 1998-2009 in 56 cities across the U.S. using a hybrid model combining land use regression and Bayesian Maximum Entropy kriging. We used Cox regression models to estimate city-specific hazard ratios (HR) associated with a 1.75 µg/m3 increase in PM2.5, the mean interquartile range in the major cities. City-specific HRs were then pooled in a summary estimate. Results. Of 33,621 women free of diabetes in 1995, 4078 developed diabetes over 16 years of follow-up; of 32,638 hypertension-free women in 1995, 9588 developed hypertension. The age-adjusted HR for diabetes was 1.09 (95% CI 1.03-1.15). After control for age, body mass index, and neighborhood socioeconomic status, it was 1.02 (95% CI 0.96-1.08). For hypertension, the respective HRs were 1.03 (95% CI 1.00-1.07) and 0.98 (95% CI 0.95-1.02). Conclusions. These results do not provide evidence of an association between PM2.5 and incident diabetes or hypertension in black women. Future work will assess the effects of traffic-related air pollutants, which were previously associated with incident diabetes in BWHS participants living in Los Angeles (Coogan et al., Circulation 2012;125:767-772).