Academic journal article Environmental Health Perspectives

Reducing Periconceptional Methylmercury Exposure: Cost-Utility Analysis for a Proposed Screening Program for Women Planning a Pregnancy in Ontario, Canada

Academic journal article Environmental Health Perspectives

Reducing Periconceptional Methylmercury Exposure: Cost-Utility Analysis for a Proposed Screening Program for Women Planning a Pregnancy in Ontario, Canada

Article excerpt

Introduction

Prenatal mercury (Hg) has been associated with adverse neurodevelopmental effects at exposures detected at levels found in the general public from exposure to methylmercury (MeHg) contaminated fish and seafood in the diet (Grandjean et al. 2003; Karagas et al. 2012; Oken et al. 2008). Subclinical neurotoxic effects, including neurophysiological and neuropsychological effects, associated with population-level Hg exposures were identified from three prospective cohort studies initiated in the 1980s, in the Faroe Islands (Budtz-Jorgensen et al. 2000, 2004; Grandjean et al. 1997, 1998), in New Zealand (Crump et al. 1998), and in the Seychelle Islands (Myers et al. 2003). Recently, the importance of adjusting for negative confounding has been reviewed (Choi et al. 2008); negative confounding results from co-exposure to beneficial polyunsaturated fatty acids (PUFAs) when Hg contaminated fish and seafood is consumed. A strengthened association of prenatal MeHg with adverse neurodevelopmental effects has been reported after adjustment for PUFAs as a covariate in prospective cohort studies in the Faroe Islands (Budtz-Jorgensen et al. 2007), in the United States (Lederman et al. 2008; Oken et al. 2008), and in a second cohort in the Seychelle Islands (Strain et al. 2008). The New Zealand study comprised mothers matched on fish intake, and thus implicitly included adjustment for PUFAs. Adverse neurodevelopment effects were detected at very low Hg exposures in two U.S. prospective cohort studies (Lederman et al. 2008; Oken et al. 2008).

The World Health Organization (Poulin and Gibb 2008) recommends adopting a population health perspective to assess the burden of exposures that can be reduced by intervention strategies. One such burden is prenatal Hg exposure; the increase in mild mental retardation in a population can be calculated from the shift in IQ distribution that results from the cognitive deficits associated with the distribution of Hg exposure in pregnant women, approximated from that in women of child-bearing age.

Several economic analyses have recently been published assessing xenobiotic metal toxicity, both mercury and lead, from a societal perspective. The burden of MeHg neurodevelopmental toxicity has been assessed in terms of IQ loss and the associated lost lifetime earnings in the United States (Rice et al. 2010; Trasande et al. 2005) and in Europe (Bellanger et al. 2013). The assessment of the economic benefits of preventing Hg exposures above three intervention thresholds in Europe (Bellanger et al. 2013) was based on the association of prenatal Hg with cognitive deficits adjusted for co-exposure to PUFAs, and a lower Hg exposure threshold for adverse effects. Roman et al. (2011) recommended development of a dose-response relationship between Hg exposure and cardiovascular risk so that this risk can be included in future population health risk assessments of Hg. An estimate of this risk was included in the economic analysis by Rice et al. (2010). Evaluations of the burden of childhood lead (Pb) exposure predate those of prenatal MeHg exposure and have been more complex, including consequences of IQ loss in outcomes of reduced quality of life and societal costs, such as remedial education costs, and increased criminal justice and health care costs (Glotzer et al. 1995; Muennig 2009). A partial cost-benefit analysis was conducted for a blood Pb screening program for children from a societal perspective in France (Pichery et al. 2011), which included remedial education costs, lost lifetime earnings associated with IQ loss, and criminal justice system costs.

The objective of this economic analysis is to estimate the quality of life to be gained from reducing prenatal Hg exposures, to determine the cost-effectiveness of a periconceptional screening program of blood Hg concentration for women planning to become pregnant in Ontario, Canada, from a societal perspective. The blood Hg distributions [Canadian Health Measures Survey (CHMS) (StatCan 2013)] were used to characterize exposures of women 20-49 years of age, and IQ loss was calculated using the association, adjusted for PUFAs, of cord blood Hg with cognitive deficits. …

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