Gestational Perfluoroalkyl Substance Exposure and DNA Methylation at Birth and 12 Years of Age: A Longitudinal Epigenome-Wide Association Study

Abstract

Background: DNA methylation alterations may underlie associations between gestational perfluoroalkyl substances (PFAS) exposure and later-life health outcomes. To the best of our knowledge, no longitudinal studies have examined the associations between gestational PFAS and DNA methylation.

Objectives: We examined associations of gestational PFAS exposure with longitudinal DNA methylation measures at birth and in adolescence using the Health Outcomes and Measures of the Environment (HOME) Study (2003-2006; Cincinnati, Ohio).

Methods: We quantified serum concentrations of perfluorooctanoate (PFOA), perfluorooctane sulfonate (PFOS), perfluorononanoate (PFNA), and perfluorohexane sulfonate (PFHxS) in mothers during pregnancy. We measured DNA methylation in cord blood ($n=266$) and peripheral leukocytes at 12 years of age ($n=160$) using the Illumina HumanMethylation EPIC BeadChip. We analyzed associations between ${\log }_2\text{-transformed}$ PFAS concentrations and repeated DNA methylation measures using linear regression with generalized estimating equations. We included interaction terms between children's age and gestational PFAS. We performed Gene Ontology enrichment analysis to identify molecular pathways. We used Project Viva (1999-2002; Boston, Massachusetts) to replicate significant associations.

Results: After adjusting for covariates, 435 cytosine-guanine dinucleotide (CpG) sites were associated with PFAS (false discovery rate, $q<0.05$). Specifically, we identified 2 CpGs for PFOS, 12 for PFOA, 8 for PFHxS, and 413 for PFNA; none overlapped. Among these, 2 CpGs for PFOA and 4 for PFNA were replicated in Project Viva. Some of the PFAS-associated CpG sites annotated to gene regions related to cancers, cognitive health, cardiovascular disease, and kidney function. We found little evidence that the associations between PFAS and DNA methylation differed by children's age.

Discussion: In these longitudinal data, PFAS biomarkers were associated with differences in several CpGs at birth and at 12 years of age in or near genes linked to some PFAS-associated health outcomes. Future studies should examine whether DNA methylation mediates associations between gestational PFAS exposure and health. https://doi.org/10.1289/EHP10118.

Figure 1.

Volcano and Manhattan plots for the epigenome-wide adjusted associations of (A) ${\log }_2\text{-transformed}$ gestational serum concentrations of PFOA or (B) PFOS or (C) PFHxS or (D) PFNA with repeated measures of DNA methylation with in the HOME Study (Cincinnati, Ohio; enrolled 2003–2006). These models were adjusted for child age and sex, annual household income (median income of each category), maternal race/ethnicity (non-Hispanic white vs. non-Hispanic black and other) and smoking during pregnancy (active smoking $\ge 3\text{\hspace{0.17em}ng}/\mathrm{mL}$ for serum cotinine, not active smoking), and cell type composition. Left panels are volcano plots showing the difference in leukocyte DNA methylation (magnitude of effect on M-value: x-axis) associated with gestational PFAS concentrations for each CpG site plotted against its negative ${\log }_{10}\text{-transformed}$ $p$-value (y-axis). Triangles represent the CpG sites with FDR $q<0.05$. For PFNA, diamonds represent the CpG sites with FDR $q<0.01$. Right panels are Manhattan plots showing negative ${\log }_{10}\text{-transformed}$ $p$-values for the associations between gestational PFAS concentrations and DNA methylation across chromosomes. Statistically significant CpG sites were defined as having an FDR $q<0.05$ (PFOA, PFOS, and PFHxS) or 0.01 (PFNA). Horizontal lines denote FDR $q<0.05$ or 0.01. Note: CpG, cytosine–guanine dinucleotide; FDR, false discovery rate; HOME, Health Outcomes and Measures of the Environment; PFHxS, perfluorohexane sulfonate; PFNA, perfluorononanoate; PFOA, perfluorooctanoate; PFOS, perfluorooctane sulfonate.