title: Chlorination disinfection by-products and risk of congenital anomalies in England and Wales.
abstract: BACKGROUND
  Increased risk of various congenital anomalies has been reported to be associated with trihalomethane (THM) exposure in the water supply.
  
  
  OBJECTIVE
  We conducted a registry-based study to determine the relationship between THM concentrations and the risk of congenital anomalies in England and Wales.
  
  
  METHODS
  We obtained congenital anomaly data from the National Congenital Anomalies System, regional registries, and the national terminations registry; THM data were obtained from water companies. Total THM (< 30, 30 to < 60, > or =60 microg/L), total brominated exposure (< 10, 10 to < 20, > or =20 microg/L), and bromoform exposure (< 2, 2 to < 4, > or =4 microg/L) were modeled at the place of residence for the first trimester of pregnancy. We included 2,605,226 live births, stillbirths, and terminations with 22,828 cases of congenital anomalies. Analyses using fixed- and random-effects models were performed for broadly defined groups of anomalies (cleft palate/lip, abdominal wall, major cardiac, neural tube, urinary and respiratory defects), a more restricted set of anomalies with better ascertainment, and for isolated and multiple anomalies. Data were adjusted for sex, maternal age, and socioeconomic status.
  
  
  RESULTS
  We found no statistically significant trends across exposure categories for either the broadly defined or more restricted sets of anomalies. For the restricted set of anomalies with isolated defects, there were significant (p < 0.05) excess risks in the high-exposure categories of total THMs for ventricular septal defects [odds ratio (OR) = 1.43; 95% confidence interval (CI), 1.00-2.04] and of bromoform for major cardiovascular defects and gastroschisis (OR = 1.18; 95% CI, 1.00-1.39; and OR = 1.38; 95% CI, 1.00-1.92, respectively).
  
  
  CONCLUSIONS
  In this large national study we found little evidence for a relationship between THM concentrations in drinking water and risk of congenital anomalies.
authors.affiliation: Small Area Health Statistics Unit, Department of Epidemiology and Public Health, Faculty of Medicine, Imperial College London, St. Mary's Campus, London, United Kingdom.
authors.forename: Mark J
authors.initials: MJ
authors.lastname: Nieuwenhuijsen
authors.forename: Mireille B
authors.initials: MB
authors.lastname: Toledano
authors.forename: James
authors.initials: J
authors.lastname: Bennett
authors.forename: Nicky
authors.initials: N
authors.lastname: Best
authors.forename: Peter
authors.initials: P
authors.lastname: Hambly
authors.forename: Cornelis
authors.initials: C
authors.lastname: de Hoogh
authors.forename: Diana
authors.initials: D
authors.lastname: Wellesley
authors.forename: Patricia A
authors.initials: PA
authors.lastname: Boyd
authors.forename: Lenore
authors.initials: L
authors.lastname: Abramsky
authors.forename: Nirupa
authors.initials: N
authors.lastname: Dattani
authors.forename: John
authors.initials: J
authors.lastname: Fawell
authors.forename: David
authors.initials: D
authors.lastname: Briggs
authors.forename: Lars
authors.initials: L
authors.lastname: Jarup
authors.forename: Paul
authors.initials: P
authors.lastname: Elliott
mesh_terms: D000013:Congenital Abnormalities / Q000453:epidemiology / Q000209:etiology*; D004203:Disinfection; D004739:England / Q000453:epidemiology; D006801:Humans; D012307:Risk Factors; D014852:Wales / Q000453:epidemiology