Objectives PFOA has been linked to several diseases, but findings are inconclusive, and there have been no incidence studies in worker populations.

Method We interviewed 3700 workers or their next-of-kin in 2009–2011 for medical history, and sought medical records to validate self-reported disease. A job-exposure matrix based on over 2000 PFOA serum measurements was used to estimate serum levels over time for each worker, while a separate estimation was made for non-occupational exposure due to drinking PFOA-contaminated water. Cumulative dose in the serum (ng/ml-years) was the metric of interest. We studied 18 disease outcomes with 15 to 1430 cases; analyses were limited to confirmed cases.

Results The median year of birth was 1951; 5% had died. The median measured serum level was 113 ng/ml in 2005 (n = 1900), compared to 4 ng/ml in the US population. Among 18 outcomes studied, only ulcerative colitis (10 year lag) showed a significant trend with increasing exposure (p = 0.05) (RRs by quartile 1.00, 3.00, 3.26, 6.57, p value trend 0.05), similar to earlier findings in a community cohort study in the same area. Positive but non-significant trends were also observed for prostate cancer and non-hepatitis liver disease, and female hypothyroidism, which have been implicated in other studies, No marked trends were seen for high cholesterol, which had been seen in the community study.

Conclusions Ulcerative colitis was linked to PFOA exposure among workers. Analyses of other diseases did not show marked trends. Data were limited by small numbers, a largely survivor cohort, and few low exposed referents.