Evaluation of a Public Health Intervention to Lower Mercury Exposure from Fish Consumption in Bermuda

Eric Dewailly,Suzanne Côté,Philippe Rouja,Martin Forde,Lyndon Robertson,Olivia Drescher,Emma Smith,Cheryl Peek-Ball,John E Mendelson

doi:10.1371/journal.pone.0047388

Abstract

ObjectivesTo assess the efficacy of a public health intervention to reduce blood mercury (Hg) concentration levels in pregnant Bermudian women.MethodsIn 2003, we conducted a study entitled “Prenatal exposure of the Bermudian Population to Environmental Contaminants” which provided Bermuda’s first baseline data on prenatal exposure to several environmental contaminants, including Hg. The mean Hg concentration from 42 healthy newborns measured in umbilical cord blood was 41.3 nmol/L, ranging from 5–160 nmol/L. This concentration was much higher than expected, being approximately 8 times the general levels found in Canada and the U.S. Furthermore, we estimated that 85% of total Hg measured was in the form of methylmercury (MeHg), indicating that seafood consumption was the primary source of Hg exposure during pregnancy in Bermuda. Locally sourced seafood was identified as the most significant possible contributory source of Hg exposure. In 2005 the authors began a complementary research programme to study the levels of Hg in local commercial fish species. Coming out of this research were specific local fish consumption guidelines issued by the Department of Health advising pregnant women to avoid those local fish species found to be high in Hg while still encouraging consumption of fish species having lower Hg levels.ResultsIn 2010, under another research initiative, we returned to Bermuda to carry out another evaluation of Hg in human blood. Hg was measured in the blood of 49 pregnant women. The arithmetic mean Hg blood concentration was 6.6 nmol/L and the geometric mean 4.2 nmol/L. The maximum concentration found was 24 nmol/L.ConclusionsHg exposure of Bermudian pregnant women has dropped significantly by a factor of around 5 since the foetal cord blood study in 2003.

Highlights

Islanders such as Bermudians generally consume large quantities of fish
In the case of Canada, comparative data were obtained from the Canadian Health Measure Survey (CHMS) which was conducted between 2007–2009 [9]
It is important to note that the CHMS samples were analysed at the National Institute of Public Health of Quebec (INSPQ) laboratory which was the same laboratory used to do the analyses for this Bermuda study

Summary

Introduction

Islanders such as Bermudians generally consume large quantities of fish. Most epidemiological and experimental studies on health related effects of exposure to mercury (Hg) strongly suggest that prenatal life is the most susceptible period for the induction of adverse effects on physical and neurological development [1,2]. The consumption of certain types of fish has been associated with higher exposures to methylmercury (MeHg) [2]. Ecotoxicological studies suggest that the problem of MeHg contamination is globalised and not restricted to industrialised countries but can be found in remote communities such as those in the Arctic [3]. Bermuda is the second most remote island community on the planet in the middle of the north Atlantic at 32 degrees latitude, some 600 nautical miles from the closest landmass

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