title: Drinking water disinfection by-product exposure and fetal growth.
abstract: BACKGROUND
  Previous studies suggest that elevated exposure to drinking water disinfection by-products (DBPs)--in particular, total trihalomethanes (TTHMs)--may lead to fetal growth restriction. We examined the effects of exposure to TTHMs, haloacetic acids, and total organic halide on the probability of delivering a small-for-gestational-age (SGA) infant and on birth weight at term.
  
  
  METHODS
  Women early in pregnancy (< or =12 weeks' gestation) or planning a pregnancy were enrolled in a prospective pregnancy study conducted in 3 US communities from 2000 through 2004. Weekly (or biweekly) water samples were collected at each site as well as individual-level participant data. Associations between DBP exposures (TTHMs, haloacetic acids, total organic halide) and fetal growth were assessed using log-binomial regression for SGA (n = 1958) and linear regression for term birth weight (n = 1854). We conducted a Bayesian analysis to examine associations between individual DBP species and fetal growth.
  
  
  RESULTS
  Haloacetic acids and total organic halide were not associated with SGA or term birth weight. The probability of delivering an SGA infant was elevated when comparing women with an average third-trimester residential TTHM concentration > or =80 microg/L to women with exposure <80 microg/L (risk ratio = 2.0 [95% confidence interval = 1.1-3.6]), but not when examining other exposure contrasts. Bayesian analyses did not support a consistent association between any DBP species and fetal growth, although these analyses were based on small sample sizes.
  
  
  CONCLUSIONS
  Our results do not suggest an adverse effect of haloacetic acid or total organic halide exposure on fetal growth. An association of TTHM with SGA was seen only for average residential concentrations above the current regulatory standard.
authors.affiliation: Department of Epidemiology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA. dilworthch@niehs.nih.gov
authors.forename: Caroline S
authors.initials: CS
authors.lastname: Hoffman
authors.forename: Pauline
authors.initials: P
authors.lastname: Mendola
authors.forename: David A
authors.initials: DA
authors.lastname: Savitz
authors.forename: Amy H
authors.initials: AH
authors.lastname: Herring
authors.forename: Dana
authors.initials: D
authors.lastname: Loomis
authors.forename: Katherine E
authors.initials: KE
authors.lastname: Hartmann
authors.forename: Philip C
authors.initials: PC
authors.lastname: Singer
authors.forename: Howard S
authors.initials: HS
authors.lastname: Weinberg
authors.forename: Andrew F
authors.initials: AF
authors.lastname: Olshan
mesh_terms: D000328:Adult; D001499:Bayes Theorem; D001724:Birth Weight / Q000187:drug effects*; D005260:Female; D005317:Fetal Growth Retardation / Q000139:chemically induced*; D006801:Humans; D006846:Hydrocarbons, Halogenated / Q000009:adverse effects* / Q000032:analysis; D007231:Infant, Newborn; D008297:Male; D011247:Pregnancy; D018508:Water Purification / Q000379:methods*; D014881:Water Supply / Q000032:analysis
chemical_list: D006846:Hydrocarbons, Halogenated