Association between arsenic, cadmium, manganese, and lead levels in private wells and birth defects prevalence in North Carolina: a semi-ecologic study.

Alison P Sanders,Joshua L Warren,Tania A Desrosiers,Robert E Meyer,Rebecca C Fry,Amy H Herring,Dianne Enright,Andrew F Olshan

doi:10.1186/1471-2458-14-955

Abstract

BackgroundToxic metals including arsenic, cadmium, manganese, and lead are known human developmental toxicants that are able to cross the placental barrier from mother to fetus. In this population-based study, we assess the association between metal concentrations in private well water and birth defect prevalence in North Carolina.MethodsA semi-ecologic study was conducted including 20,151 infants born between 2003 and 2008 with selected birth defects (cases) identified by the North Carolina Birth Defects Monitoring Program, and 668,381 non-malformed infants (controls). Maternal residences at delivery and over 10,000 well locations measured for metals by the North Carolina Division of Public Health were geocoded. The average level of each metal was calculated among wells sampled within North Carolina census tracts. Individual exposure was assigned as the average metal level of the census tract that contained the geocoded maternal residence. Prevalence ratios (PR) with 95% confidence intervals (CI) were calculated to estimate the association between the prevalence of birth defects in the highest category (≥90th percentile) of average census tract metal levels and compared to the lowest category (≤50th percentile).ResultsStatewide, private well metal levels exceeded the EPA Maximum Contaminant Level (MCL) or secondary MCL for arsenic, cadmium, manganese, and lead in 2.4, 0.1, 20.5, and 3.1 percent of wells tested. Elevated manganese levels were statistically significantly associated with a higher prevalence of conotruncal heart defects (PR: 1.6 95% CI: 1.1-2.5).ConclusionsThese findings suggest an ecologic association between higher manganese concentrations in drinking water and the prevalence of conotruncal heart defects.Electronic supplementary materialThe online version of this article (doi:10.1186/1471-2458-14-955) contains supplementary material, which is available to authorized users.

Highlights

IntroductionCadmium, manganese, and lead are known human developmental toxicants that are able to cross the placental barrier from mother to fetus
Toxic metals including arsenic, cadmium, manganese, and lead are known human developmental toxicants that are able to cross the placental barrier from mother to fetus
Our analyses identified three notable findings: (i) metal levels are elevated in private wells across the state and some metals such as arsenic and manganese co-occur, (ii) residence in manganese-exposed census tracts was statistically significantly associated with increased prevalence of conotruncal heart defects, and (iii) there is suggestive evidence of an interactive effect between residence in arsenic- and manganese-exposed census tracts and the prevalence of conotruncal heart defects

Summary

Introduction

Cadmium, manganese, and lead are known human developmental toxicants that are able to cross the placental barrier from mother to fetus In this population-based study, we assess the association between metal concentrations in private well water and birth defect prevalence in North Carolina. Exposure to arsenic- and lead-contaminated drinking water has been associated with an increased occurrence of congenital heart defects (CHDs) [19,20,21] as well as neural tube defects (NTDs) in human populations [22]. While these studies demonstrated elevated associations, some of the reported 95% confidence intervals were consistent with unity. It is clear from animal studies that metal exposure can result in structural malformation; there have been few population-based human studies that have examined such relationships

Methods

Results

Discussion

Conclusion