Relation between perfluorooctanoic acid exposure and strokes in a large cohort living near a chemical plant

A community around a chemical plant was exposed to perfluorooctanoic acid (PFOA) for over 50 years, primarily through drinking water. One cohort study of PFOA-exposed workers found a positive trend with stroke mortality. Other, cross-sectional, studies have found positive associations between serum PFOA and risk factors for stroke, including cholesterol, uric acid, and hypertension. We examined the relation between PFOA exposure and incident strokes (including transient ischemic attacks) in community members, including plant workers. Participants completed surveys in 2008–2011 regarding medical history, health-related behaviors, and demographics. Cox proportional hazards models were used to compare the hazard of stroke in relation to time-varying estimated cumulative PFOA serum levels, adjusting for confounders. Of 32,254 survey participants with exposure estimates, 1596 self-reported stroke, of whom 919 had their self-report validated by medical records review. After excluding subjects with strokes before age 20 and subjects born before 1920 or with missing covariate data, 825 cases remained. Compared with the lowest quintile of cumulative exposure, subsequent quintiles in the retrospective analysis had hazard ratios of 1.39 [95% confidence interval, 1.11–1.76], 1.36 [1.08–1.71], 1.45 [1.15–1.82], and 1.13 [0.90–1.44]. Tests for trend with linear or log-transformed cumulative dose were not significant (p=0.52 and 0.59, respectively). Neither an analysis with a 5-year lag, nor prospective analyses restricted to 2005–2011 (302 cases) found positive trends (p=0.44, positive trend; p=0.28, negative trend, respectively). Overall, our data provide only modest evidence of an association between PFOA and stroke incidence.