Risk assessment of methylmercury in pregnant women and newborns in the island of Madeira (Portugal) using exposure biomarkers and food-frequency questionnaires

ABSTRACT

Methylmercury (MeHg) is a contaminant present in fish which exerts a severe impact on health predominantly exhibiting neurotoxicity that might irreversibly affect fetal neurodevelopment. Fish consumption in Portugal is the third highest in the world, particularly high in regions with fishing tradition such as the Madeira Archipelago. Therefore, this study aimed at assessing the risk of exposure to MeHg in a population of pregnant women residing in Madeira. Blood samples from pregnant women (533) and umbilical cord (194) were collected from volunteer participants collected at primary health services in Madeira (Portugal) and analyzed for total mercury (HgT) level. A food-frequency questionnaire was used to estimate exposure and indices of risk while HgT in blood were correlated with estimated exposure. Analysis of HgT levels in blood indicated that 30% of pregnant women surpassed the maximum safe level of 10 µg/L recommended by the WHO, which was derived from the consumption of predatory fish, rich in MeHg. In addition, HgT levels in cord blood were 1.3 fold higher than in maternal blood, indicating the high risk of exposure to MeHg in this population. It is thus important to provide nutritional advice concerning fish consumption as a food choice in order to reduce fetal exposure and potential neurologic damage.

KEYWORDS:

• Risk assessment
• methylmercury
• fish consumption
• exposure assessment
• susceptible populations

Acknowledgments

We thank the personal of SESARAM (Madeira Island Health Unit) that were related with this study such as Dr. Miguel Ferreira, Dr. Paula Pinto, Dr. Graça Andrade, Nurse José Manuel Freitas, and technicians Maria da Luz and Noélia. Without their dedication, this research wouldn´t have been possible. We also thank Dr. Rui Pinto from the Faculty of Pharmacy of the University of Lisbon for his logistic support that was so important for the transport of samples.

Conflict of interest statement

The authors declare that there are no conflicts of interest.

Additional information

Funding

This study was financed by Fundação para a Ciência e Tecnologia (FCT) (www.fct.pt) through the MERTOX project (PTDC/QUI- BIQ/117281/2010) and iMed.ULisboa’s strategic project UID/DTP/04138/2013. Vasco Branco is supported by a Post-Doc fellowship (SFRH/BPD/85219/2012) also from FCT.