Temporal variation of total mercury levels in the hair of pregnant women from the Maternal-Infant Research on Environmental Chemicals (MIREC) study

Prenatal exposure to total mercury (T-Hg) comes from both natural and anthropogenic sources. T-Hg can cross the blood-brain and placental barriers, and may be associated with future neurological and physiological dysfunctions. Scalp hair is an optimal and non-invasive indicator of chronic T-Hg exposure. As part of the Maternal-Infant Research on Environmental Chemicals (MIREC) Study, hair samples from 350 women were collected within weeks after giving birth, to determine temporal variations in T-Hg levels from preconception to delivery, and to compare these levels to corresponding levels measured in other matrices (maternal and umbilical cord blood, and infant's meconium). A maximum of 12 one-cm hair segments were cut starting at the scalp; segments closer to the scalp reflected recent exposure (within the last month). For proper comparison, the hair segments were matched with the collection dates for other matrices. GM hair T-Hg levels greatly decreased during pregnancy, from 0.26 mu g g(-1) (preconception or full-length hair) to 0.18 mu g g(-1) (at delivery or segments closer to the scalp). A similar decreasing trend was found for T-Hg in maternal blood: 1st trimester (0.60 mu g L-1) to 3rd trimester (0.47 mu g L-1). The median hair-to-blood ratios of T-Hg levels varied from 364 (1st trimester), to 408 (3rd trimester), to 229 (cord blood). Very low T-Hg levels were detected in meconium. Mercury levels in blood and hair correlated with consumption of large predatory fish. Crown Copyright (C) 2020 Published by Elsevier Ltd.

Automated summary

Prenatal exposure to total mercury (T-Hg) from both natural and anthropogenic sources can have potential impacts on future neurological and physiological functions. Hair is a useful indicator of chronic T-Hg exposure, and studies have shown a decrease in T-Hg levels in both hair and maternal blood during pregnancy. Low T-Hg levels were found in meconium, and mercury levels in blood and hair were correlated with consumption of large predatory fish.