Prospective Study of Mercury Exposure from Pregnancy and Its Relation with Telomere Length in Spanish Children

Abstract

Telomere length (TL) is a biomarker linked to age-related diseases based on its sensitivity to oxidative DNA damage and inflammation. Methylmercury (MeHg) is a common pollutant in fish. It may induce oxidative stress leading to shorter TL. However, previous research showed contradictory results and dose-concentration dependencies and non-linear relationships have been suggested. This study was carried out in the INMA multi-center birth cohort prospective study comprising mother-child pairs belonging to four different Spanish cohorts from 2004. We set out to assess the association between prenatal and 4-year-old children's exposure to MeHg with TL at the ages of 4 and 7-9 years (n = 1083). Sociodemographic and lifestyle covariates, as well as fish consumption and estimated polyunsaturated fatty acid content, were also considered in the analyses. A mixed regression model and interaction models based on sex and fish consumption were performed. Sensitivity analyses to assess confounding effects were also built by adding to the main model other pollutants present in fish, such as other metals, polychlorinated biphenyls, and dichlorodiphenyldichloroethylene, as well as single nucleotide polymorphisms in the TERT and CLPTM1L genes. Longer TL was associated with higher paternal age and female sex in children. MeHg concentrations were related to higher maternal age, being primiparous, working during pregnancy, higher education, and higher fish consumption. No significant associations between prenatal or postnatal MeHg concentrations and TL were found. Sensitivity analyses showed no MeHg modification effect on TL. Further research is needed to elucidate the TL modifications found by previous studies associated with MeHg and fish consumption.