Journal Article

Prenatal Exposure to Mercury: Associations with Global DNA Methylation and Hydroxymethylation in Cord Blood and in Childhood

Oken, Emily, Hivert, Marie-France, Rifas-Shiman, Sheryl L., Brennan, Kasey J., Godderis, Lode, Amarasiriwardena, Chitra J., Gillman, Matthew W., DeMeo, Dawn L., Duca, Radu-Corneliu, Baccarelli, Andrea A., Cardenas, Andres, Navas-Acien, Ana, Litonjua, Augusto A.

2017

Overview

Mercury is a global pollutant, and prenatal exposure is associated with adverse health effects. To date, no studies have evaluated the association between prenatal mercury exposure and DNA hydroxymethylation, an epigenetic modification important for tissue differentiation and embryonic development. We sought to evaluate the association between prenatal mercury exposure and offspring global DNA methylation and hydroxymethylation at birth and test for persistence of the association in childhood. Within Project Viva, a U.S. prebirth cohort, we examined associations of maternal second trimester red blood cell mercury (RBC-Hg) concentrations with global 5-hydroxymethylcytosine (%-5hmC) and 5-methylcytosine (%-5mC) DNA content in blood collected at birth ( =306), early childhood ( =68; 2.9 to 4.9 y), and midchildhood ( =260; 6.7 to 10.5 y). Median prenatal RBC-Hg concentration was 3.23μg/g [interquartile range (IQR)=3.29]. At birth, median cord blood %-5mC, %-5hmC, and their ratio were 4.95%, 0.22%, and 24.37, respectively. The mean adjusted difference [95% confidence interval (CI)] of blood %-5hmC for a doubling in prenatal RBC-Hg concentration was -0.013% (-0.029, 0.002), -0.031% (-0.056, -0.006), and 0.005% (-0.007, 0.018) at birth, early, and midchildhood, respectively. The corresponding relative adjusted change in the genomic ratio of %-5mC to %-5hmC for a doubling in prenatal RBC-Hg concentration was 4.70% (0.04, 9.58), 22.42% (7.73, 39.11), and 0.73% (-4.18, 5.88) at birth, early, and midchildhood, respectively. No associations were present between prenatal maternal RBC-Hg and %-5mC at any time point. Prenatal mercury exposure was associated with lower %-5hmC genomic content and a corresponding increase in the ratio of %-5mC to %-5hmC in cord blood. This association was persistent in early but not midchildhood blood. Our results demonstrate the potential malleability of epigenetic modifications associated with mercury exposure . https://doi.org/10.1289/EHP1467.

• Publisher: National Institute of Environmental Health Sciences,Environmental Health Perspectives
• Subject: Biomarkers / Birth / Birth weight / Blood / Child / Childbirth & labor / Childhood / Children / Chromatography / Confidence intervals / Cord blood / Deoxyribonucleic acid / Differentiation (biology) / DNA / DNA Methylation / Embryogenesis / Embryonic growth stage / Environmental Pollutants / Epigenesis, Genetic / Epigenetics / Erythrocytes / Ethnicity / Exposure / Female / Fetal Blood / Fetuses / Gene expression / Genetic aspects / Genetic research / Genetic testing / Gestational age / Health aspects / Health risks / Humans / Intrauterine exposure / Maternal Exposure - statistics & numerical data / Mercury / Mercury (Metal) / Mercury - metabolism / Methylation / Mothers / Offspring / Pregnancy / Prenatal experience / Prenatal exposure / Prenatal Exposure Delayed Effects / Prenatal influences / Stem cells / Toxicity