Economic benefits of methylmercury exposure control in Europe: Monetary value of neurotoxicity prevention

Abstract

BackgroundDue to global mercury pollution and the adverse health effects of prenatal exposure to methylmercury (MeHg), an assessment of the economic benefits of prevented developmental neurotoxicity is necessary for any cost-benefit analysis.MethodsDistributions of hair-Hg concentrations among women of reproductive age were obtained from the DEMOCOPHES project (1,875 subjects in 17 countries) and literature data (6,820 subjects from 8 countries). The exposures were assumed to comply with log-normal distributions. Neurotoxicity effects were estimated from a linear dose-response function with a slope of 0.465 Intelligence Quotient (IQ) point reduction per μg/g increase in the maternal hair-Hg concentration during pregnancy, assuming no deficits below a hair-Hg limit of 0.58 μg/g thought to be safe. A logarithmic IQ response was used in sensitivity analyses. The estimated IQ benefit cost was based on lifetime income, adjusted for purchasing power parity.ResultsThe hair-mercury concentrations were the highest in Southern Europe and lowest in Eastern Europe. The results suggest that, within the EU, more than 1.8 million children are born every year with MeHg exposures above the limit of 0.58 μg/g, and about 200,000 births exceed a higher limit of 2.5 μg/g proposed by the World Health Organization (WHO). The total annual benefits of exposure prevention within the EU were estimated at more than 600,000 IQ points per year, corresponding to a total economic benefit between €8,000 million and €9,000 million per year. About four-fold higher values were obtained when using the logarithmic response function, while adjustment for productivity resulted in slightly lower total benefits. These calculations do not include the less tangible advantages of protecting brain development against neurotoxicity or any other adverse effects.ConclusionsThese estimates document that efforts to combat mercury pollution and to reduce MeHg exposures will have very substantial economic benefits in Europe, mainly in southern countries. Some data may not be entirely representative, some countries were not covered, and anticipated changes in mercury pollution all suggest a need for extended biomonitoring of human MeHg exposure.

Public health benefits of hair-mercury analysis and dietary advice in lowering methylmercury exposure in pregnant women

“…Elevated exposure to methylmercury from contaminated seafood constitutes a serious public health problem, and societal costs from developmental neurotoxicity in the EU has been estimated to approach €10 billion per year [5]. As mercury contamination of seafood cannot be minimized in the short term, the only feasible public health intervention must rely on some form of dietary advice.…”

“…The same laboratory carried out the analyses of Danish samples in the EU-wide study [5]. The 1-cm samples reflect mercury deposited approximately 30-60 days prior to collection (the most recent 30 days of growth has not yet emerged above the scalp) [17].…”

“…Methylmercury is the most important mercury species in the environment where it is bioaccumulated in the muscle tissue of large, long-lived predatory fish, such as swordfish, shark and tuna; seafood is therefore the main source of exposure in humans [2]. While seafood provides nutrients essential for foetal development [4], elevated methylmercury exposure can cause developmental neurotoxicity and associated losses of IQ points [2]; the societal costs in the EU from an annual loss of more than 600,000 IQ points have been calculated to be about €8-9 billion per year [5]. Accordingly, public health interventions to limit methylmercury exposures should focus on avoidance of fish known to be high in mercury [6], while avoiding simplified advisories that may scare women from eating otherwise healthy seafood [7].…”

“…Even the lowest official limit, i.e., 1.0 µg/g hair used by the U.S. Environmental Protection Agency [11], does not take into the impact of exposure misclassification [12] nor genetic predisposition to methylmercury toxicity [13]. An updated calculation suggests a more protective exposure limit of about 0.58 µg/g hair [12], and this limit was applied in an EU-wide comparison study [5] and in the present study as well.…”

“…The study was carried out in Denmark, where hair-mercury concentrations in women are known to be higher than those in neighbouring countries (37% exceed a safe limit in Denmark, as compared to 28% in Norway and Sweden); assuming that exposures are similar in pregnant women, prevention of excess exposures in Denmark were estimated to represent an annual value of approximately €100 million [5]. As mercury contamination of seafood cannot be reduced in the short term, public health interventions must focus on dietary habits.…”