Exposure assessment of Portuguese women of childbearing age to methylmercury: first results of a human biomonitoring study

Em colaboração com o DEPMethylmercury (MeHg) is a toxic compound that undergoes bioaccumulation in the aquatic food chain. Fish, especially predatory species such as tuna or swordfish, are an important human exposure source. Portugal presents the highest consumption of fishery and aquaculture products in the European Union (EU), above the EU and world average. The central nervous system is the main target of MeHg and the prenatal period represents a period of greatest vulnerability regarding neurodevelopmental effects on the fetus. As recommended by EFSA, the risk of exceeding the MeHg tolerable dose through consumption of fish and seafood should be properly assessed by each member state. Total mercury concentration in blood is usually considered a suitable biomarker for estimating short-term internal exposure to methylmercury, in individuals with regular fish consumption. The present study aimed at evaluating the exposure of Portuguese women of childbearing age to MeHg through human biomonitoring. For this study, 300 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, http://www.insef.pt/). Total mercury content was determined in whole blood samples collected in 2015 by thermal decomposition and amalgamation atomic absorption spectrophotometry (TDA/AAS). Two samples had total mercury levels below LOQ (0.5 μg/L), and in the remaining (n=298), mercury levels ranged from 0.6 to 35 μg/L. Almost 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 an increased risk of adverse health outcomes. 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 prevent human exposure to this compound, especially in particularly susceptible populations.N/