title: Exposure to trihalomethanes in drinking water and small-for-gestational-age births.
abstract: BACKGROUND
  Trihalomethanes in drinking water have been associated with higher occurrence of small-for-gestational-age (SGA) births, although results have been inconsistent.
  
  
  METHODS
  We geocoded residential address for mother of live, singleton, term births to 33 water distribution systems in a large metropolitan area of New South Wales, Australia (314,982 births between 1998 and 2004) and classified births into <10th percentile and ≥ 10 percentile of weight for gestational age. Mean trihalomethane exposure was estimated by trimester and for the entire pregnancy based on monthly sampling in each of the 33 water distribution systems. We estimated the relative risk (RR) of SGA for exposure to trihalomethanes using log-binomial regression adjusting for confounding.
  
  
  RESULTS
  SGA births increased with mother's third-trimester exposure to chloroform (RR = 1.04 [95% confidence interval = 1.02-1.06], across an interquartile range [IQR] = 25 μg/L) and bromodichloromethane (1.02 [1.01-1.04], 5 μg/L). Larger associations were found for SGA less than third percentile. Smoking modified the effects of trihalomethane exposure, with generally larger associations in births to nonsmoking mother and weaker or protective associations in births to smoking mothers.
  
  
  CONCLUSIONS
  : Mothers' exposures during pregnancy to total trihalomethane as well as to chloroform and bromodichloromethane were associated with SGA. These associations were modified by maternal smoking during pregnancy.
authors.affiliation: University Center for Rural Health - North Coast, Medical School, University of Sydney, Lismore, New South Wales, Australia. summerhayes.richard@gmail.com
authors.forename: Richard J
authors.initials: RJ
authors.lastname: Summerhayes
authors.forename: Geoffrey G
authors.initials: GG
authors.lastname: Morgan
authors.forename: Howard P
authors.initials: HP
authors.lastname: Edwards
authors.forename: Douglas
authors.initials: D
authors.lastname: Lincoln
authors.forename: Arul
authors.initials: A
authors.lastname: Earnest
authors.forename: Bayzidur
authors.initials: B
authors.lastname: Rahman
authors.forename: John R
authors.initials: JR
authors.lastname: Beard
mesh_terms: D000328:Adult; D002725:Chloroform / Q000009:adverse effects; D060766:Drinking Water / Q000009:adverse effects; D005260:Female; D006801:Humans; D007231:Infant, Newborn; D007236:Infant, Small for Gestational Age; D008297:Male; D016012:Poisson Distribution; D011247:Pregnancy; D011264:Pregnancy Trimesters / Q000187:drug effects; D011297:Prenatal Exposure Delayed Effects / Q000139:chemically induced*; D012306:Risk; D012907:Smoking / Q000009:adverse effects; D022882:Trihalomethanes / Q000009:adverse effects*; D055815:Young Adult
chemical_list: D060766:Drinking Water; D022882:Trihalomethanes; C025191:bromodichloromethane; D002725:Chloroform