Air Pollution, PFOA, and Preeclampsia in the C8 Studies

Abstract

Background/Aim: Preeclampsia is a type of pregnancy-induced hypertension that also includes proteinuria. Traffic-related particulate air pollution has been linked to preeclampsia in some previous studies. The C8 Study of perfluorooctanoate (PFOA) and preeclampsia did not consider potential confounding by air pollution. We assessed the association between distance to road (DTR), a marker of traffic related air pollution, and preeclampsia in an area with elevated exposure to PFOA from drinking water contaminated by chemical plant releases.Methods: We calculated distance to nearest major road (class A1, A2, or A3) for 5,960 pregnancies occurring between 1990 and 2006 in twelve Ohio and West Virginia counties that were included in previous publications from the C8 Studies. Generalized additive models (GAM) included smoothing for maternal location at birth to assess spatial patterns of preeclampsia risk. We adjusted for estimated annual serum PFOA exposure, exposure year, maternal age at time of pregnancy, parity, education, and smoking status. We then assessed the contribution of DTR to preeclampsia risk with a spatial GAM and a logistic regression without location.Results: For our adjusted model with PFOA exposure, the odds ratio (OR) for preeclampsia was 1.01 (95% confidence interval (CI): 0.92, 1.12) per interquartile shift in log-transformed DTR in meters. The ORs for preeclampsia analyses with and without adjustment for DTR were both 1.11 (95% CI: 0.99, 1.25) per interquartile shift in log-transformed PFOA. Residual spatial patterns in preeclampsia risk were present after PFOA adjustment and did not change with inclusion of DTR. Conclusion: No associations between DTR and preeclampsia were observed in this large, population-based study with elevated PFOA exposure. We did not find any evidence to suggest DTR confounded the relationship observed with estimated serum PFOA levels. Residual spatial patterns of preeclampsia may be due to other unmeasured confounders or limited adjustment for socioeconomic status.