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Open Access Research

Mercury in fish and adverse reproductive outcomes: results from South Carolina

James B Burch12*, Sara Wagner Robb3, Robin Puett4, Bo Cai1, Rebecca Wilkerson5, Wilfried Karmaus6, John Vena7 and Erik Svendsen8

Author Affiliations

1 Department of Epidemiology & Biostatistics, Arnold School of Public Health, University of South Carolina, Columbia, SC, USA

2 WJB Dorn Veteran’s Affairs Medical Center, Columbia, SC, USA

3 College of Public Health, Department of Epidemiology and Biostatistics, University of Georgia, Athens, GA, USA

4 Maryland Institute for Applied Environmental Health, University of Maryland, College Park, MD, USA

5 Institute for Families in Society, University of South Carolina, Columbia, SC, USA

6 Division of Epidemiology, Biostatistics, and Environmental Health, School of Public Health, University of Memphis, Memphis, TN, USA

7 Department of Public Health Sciences, Medical University of South Carolina, Charleston, SC, USA

8 Department of Global Environmental Health Sciences, Tulane University School of Public Health and Tropical Medicine, New Orleans, LA, USA

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International Journal of Health Geographics 2014, 13:30  doi:10.1186/1476-072X-13-30

Published: 15 August 2014

Abstract

Background

Mercury is a metal with widespread distribution in aquatic ecosystems and significant neurodevelopmental toxicity in humans. Fish biomonitoring for total mercury has been conducted in South Carolina (SC) since 1976, and consumption advisories have been posted for many SC waterways. However, there is limited information on the potential reproductive impacts of mercury due to recreational or subsistence fish consumption.

Methods

To address this issue, geocoded residential locations for live births from the Vital Statistics Registry (1995–2005, N = 362,625) were linked with spatially interpolated total mercury concentrations in fish to estimate potential mercury exposure from consumption of locally caught fish. Generalized estimating equations were used to test the hypothesis that risk of low birth weight (LBW, <2,500 grams) or preterm birth (PTB, <37 weeks clinical gestation) was greater among women living in areas with elevated total mercury in fish, after adjustment for confounding. Separate analyses estimated term LBW and PTB risks using residential proximity to rivers with fish consumption advisories to characterize exposure.

Results

Term LBW was more likely among women residing in areas in the upper quartile of predicted total mercury in fish (odds ratio [OR] = 1.04; 95% confidence interval [CI]: 1.00-1.09) or within 8 kilometers of a river with a ‘do not eat’ fish advisory (1.05; 1.00-1.11) compared to the lowest quartile, or rivers without fish consumption restrictions, respectively. When stratified by race, risks for term LBW or PTB were 10-18% more likely among African-American (AA) mothers living in areas with the highest total fish mercury concentrations.

Conclusions

To our knowledge, this is the first study to examine the relationship between fish total mercury concentrations and adverse reproductive outcomes in a large population-based sample that included AA women. The ecologic nature of exposure assessment in this study precludes causal inference. However, the results suggest a need for more detailed investigations to characterize patterns of local fish consumption and potential dose–response relationships between mercury exposure and adverse reproductive outcomes, particularly among AA mothers.

Keywords:
Low birth weight; Environmental public health tracking; Geographic information system; Preterm birth