title: Association between arsenic, cadmium, manganese, and lead levels in private wells and birth defects prevalence in North Carolina: a semi-ecologic study.
abstract: BACKGROUND
  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. In this population-based study, we assess the association between metal concentrations in private well water and birth defect prevalence in North Carolina.
  
  
  METHODS
  A 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).
  
  
  RESULTS
  Statewide, 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).
  
  
  CONCLUSIONS
  These findings suggest an ecologic association between higher manganese concentrations in drinking water and the prevalence of conotruncal heart defects.
authors.forename: Alison P
authors.initials: AP
authors.lastname: Sanders
authors.forename: Tania A
authors.initials: TA
authors.lastname: Desrosiers
authors.forename: Joshua L
authors.initials: JL
authors.lastname: Warren
authors.forename: Amy H
authors.initials: AH
authors.lastname: Herring
authors.forename: Dianne
authors.initials: D
authors.lastname: Enright
authors.forename: Andrew F
authors.initials: AF
authors.lastname: Olshan
authors.forename: Robert E
authors.initials: RE
authors.lastname: Meyer
authors.affiliation: Department of Environmental Sciences and Engineering, Gillings School of Global Public Health, University of North Carolina, Chapel Hill, NC, USA. rfry@unc.edu.
authors.forename: Rebecca C
authors.initials: RC
authors.lastname: Fry
mesh_terms: D000328:Adult; D001151:Arsenic / Q000009:adverse effects / Q000032:analysis; D002104:Cadmium / Q000009:adverse effects / Q000032:analysis; D005260:Female; D006330:Heart Defects, Congenital / Q000453:epidemiology / Q000209:etiology*; D000075322:Heavy Metal Poisoning; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D007854:Lead / Q000009:adverse effects / Q000032:analysis; D008297:Male; D008345:Manganese / Q000009:adverse effects / Q000032:analysis; D018811:Maternal Exposure / Q000009:adverse effects*; D019216:Metals, Heavy / Q000009:adverse effects* / Q000032:analysis; D009657:North Carolina / Q000453:epidemiology; D011041:Poisoning / Q000150:complications*; D011247:Pregnancy; D015995:Prevalence; D014874:Water Pollutants, Chemical / Q000009:adverse effects*; D014881:Water Supply / Q000032:analysis*; D055815:Young Adult
chemical_list: D019216:Metals, Heavy; D014874:Water Pollutants, Chemical; D002104:Cadmium; D007854:Lead; D008345:Manganese; D001151:Arsenic