Temporal variation of total mercury levels in the hair of pregnant women from the Maternal-Infant Research on Environmental Chemicals (MIREC) study
- DOI
- Language of the publication
- English
- Date
- 2020-09-24
- Type
- Article
- Author(s)
- Lukina, Anna O.
- Fisher, Mandy
- Khoury, Cheryl
- Than, John
- Guay, Mireille
- Paradis, Jean-François
- Arbuckle, Tye E.
- Legrand, Melissa
- Publisher
- Elsevier
Abstract
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 μg g−1 (preconception or full-length hair) to 0.18 μg 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 μg L−1) to 3rd trimester (0.47 μg 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.
Plain language summary
Health Canada is responsible for protecting the health of Canadians by assessing and managing the risks associated with exposure to chemicals in the environment. To assess a population’s exposure to a given chemical, chemical levels are often measured in hair and blood samples. Mercury is a heavy metal that is abundantly used in various industrial activities, including gold mining, fossil fuel combustion, production of medical and measuring devices, batteries, fluorescent light bulbs, cosmetics, pharmaceuticals, and for dental amalgam fillings. The more an individual is exposed to mercury, the higher levels will be detected in hair and blood. Different people will have different exposures, and the majority of mercury exposure comes from consumption of large predatory fish and shellfish. This study measured total mercury levels in hair, blood (1st and 3rd trimesters of pregnancy), umbilical cord blood, breast milk and infant’s meconium. A sub-sample of 350 women from the Maternal-Infant Research on Environmental Chemicals (MIREC) Study was taken for the current study. This study was designed to characterise mercury levels in hair over the course of pregnancy, by collecting a maximum 12 cm hair segments, assuming that hair grows on average 1 cm/month. This study also compared hair-blood, hair-breast milk and hair-meconium, to see how total mercury levels changed during pregnancy at different samples. Total mercury levels decreased in blood and hair samples over the course of pregnancy. Very low total mercury levels were found in meconium and breast milk samples. In conclusion, on average mercury levels decreased during pregnancy, which may be the result of dietary adjustments or normal blood volume changes during pregnancy.
Subject
- Health,
- Health and safety