title: Household water source and the risk of childhood brain tumours: results of the SEARCH International Brain Tumor Study.
abstract: BACKGROUND
  The period in utero is a time of increased vulnerability. Offspring of pregnant women exposed to carcinogenic substances in drinking water may be more likely to develop cancer. We examined whether household water source and the presence of nitrates or nitrites in residential water were associated with increased risks of childhood brain tumours (CBT).
  
  
  METHODS
  We used data from a multicentre, case-control study with maternal information on residential water source, and nitrate/nitrite levels of tap water measured by dipstick. Subjects included 836 CBT cases and 1485 controls from five countries.
  
  
  RESULTS
  The risks of CBT associated with reliance on well water (versus public water) during pregnancy varied widely, with significantly increased risks noted in two (of seven) regions and a decreased risk observed in one region. CBT risk did not increase with increasing nitrate levels. However, our results based on tap water tested in the pregnancy residences suggest the risk of astrocytoma may be associated with increasing levels of nitrite (odds ratio [OR] = 4.3, 95% CI: 1.4, 12.6 for nitrite levels of 1-<5 mg/l nitrite ion; OR = 5.7, 95% CI: 1.2, 27.2 of nitrite > or =5 mg/l).
  
  
  CONCLUSIONS
  These results should be interpreted with caution because women's recollection of water sources may have contained inaccuracies, and nitrate and nitrite measurements, available for only a portion of subjects, were often obtained years after the pregnancies occurred. However, our results suggest a need for closer evaluation of well water content in some regions and the possibility that a nitrite-related water exposure may be associated with CBT.
authors.affiliation: Public Health Sciences Division, Fred Hutchinson Cancer Research Center, PO Box 19024, Mail Stop M4-C308, Seattle, WA 98109-1024, USA. bmueller@fhcrc.org
authors.forename: Beth A
authors.initials: BA
authors.lastname: Mueller
authors.forename: Susan
authors.initials: S
authors.lastname: Searles Nielsen
authors.forename: Susan
authors.initials: S
authors.lastname: Preston-Martin
authors.forename: Elizabeth A
authors.initials: EA
authors.lastname: Holly
authors.forename: Sylvaine
authors.initials: S
authors.lastname: Cordier
authors.forename: Graziella
authors.initials: G
authors.lastname: Filippini
authors.forename: Raphael
authors.initials: R
authors.lastname: Peris-Bonet
authors.forename: N W
authors.initials: NW
authors.lastname: Choi
mesh_terms: D001254:Astrocytoma / Q000139:chemically induced* / Q000453:epidemiology; D001932:Brain Neoplasms / Q000139:chemically induced* / Q000453:epidemiology; D016022:Case-Control Studies; D002648:Child; D005260:Female; D006801:Humans; D018811:Maternal Exposure; D009566:Nitrates / Q000633:toxicity*; D011247:Pregnancy; D012306:Risk; D014881:Water Supply
chemical_list: D009566:Nitrates