Methylmercury: A Human Biomonitoring Study of Portuguese Women of Childbearing Age

Abstract

BACKGROUND AND AIM: Methylmercury (MeHg) is a toxic compound that undergoes bioaccumulation in the aquatic food chain. Predatory fish species are an important human exposure source. Portugal has the highest consumption of fishery products in the European Union (EU), above the EU and world average. The main target of MeHg is the central nervous system and the prenatal period represents a period of greatest vulnerability regarding neurodevelopmental effects on the foetus. Human biomonitoring (HBM) allows direct exposure assessment of human exposure to chemical compounds. Total mercury (THg) concentration in blood is usually considered an appropriate biomarker for estimating short-term internal exposure to MeHg in individuals with regular fish consumption. The aim of the present study was to evaluate the exposure of Portuguese women of childbearing age to MeHg through HBM. METHODS: Three hundred Portuguese women of childbearing age (25 to 44 years) were randomly selected among the participants in a cross-sectional epidemiological study carried out in Portugal (INSEF) in 2015. THg content was determined in whole blood samples by thermal decomposition and amalgamation atomic absorption spectrophotometry (TDA/AAS). RESULTS:Two samples had THg levels below LOQ (0.5 µg/L), and in the remaining (n=298), THg levels ranged from 0.6 to 35.0 µg/L. About 52% of the samples had values below 5 µg/L, a HBM value below which no adverse health effects are expected. However, 48% of samples revealed levels above 5 µg/L and therefore presented risk of adverse health effects. Blood mercury concentration values were higher in older women, in higher education level and residents in the Autonomous Region of Madeira, with statistically significant differences compared to the other groups (p0.05). CONCLUSIONS:This study reinforces the need to develop and implement in Portugal strategies regarding risk communication focused on the selection of fish species with lower MeHg concentration in order to reduce human exposure to this compound. KEYWORDS: Biomarkers of exposure, Exposure assessment, Food/nutrition, Heavy metals, Risk assessment