title: Nitrates in drinking water and the risk of death from brain cancer: does hardness in drinking water matter?
abstract: The objectives of this study were to (1) examine the relationship between nitrate levels in public water supplies and risk of death from brain cancer and (2) determine whether calcium (Ca) and magnesium (Mg) levels in drinking water might modify the influence of nitrates on development of brain cancer. A matched cancer case-control study was used to investigate the relationship between the risk of death from brain cancer and exposure to nitrates in drinking water in Taiwan. All brain cancer deaths of Taiwan residents from 2003 through 2008 were obtained from the Bureau of Vital Statistics of the Taiwan Provincial Department of Health. Controls were deaths from other causes and were pair-matched to cancer cases by gender, year of birth, and year of death. Information on the levels of nitrate-nitrogen (NO₃-N), Ca, and Mg in drinking water was obtained from Taiwan Water Supply Corporation (TWSC). The municipality of residence for cancer cases and controls was presumed to be the source of the subject's NO₃-N, Ca, and Mg exposure via drinking water. Relative to individuals whose NO₃-N exposure level was <0.38 ppm, the adjusted OR (95% CI) for brain cancer occurrence was 1.04 (0.85-1.27) for individuals who resided in municipalities served by drinking water with a NO₃-N exposure ≥ 0.38 ppm. No marked effect modification was observed due to Ca and Mg intake via drinking water on brain cancer occurrence.
authors.affiliation: Institute of Occupational Safety and Health, College of Health Sciences, Kaohsiung Medical University, Kaohsiung, Taiwan.
authors.forename: Chi-Kung
authors.initials: CK
authors.lastname: Ho
authors.forename: Ya-Hui
authors.initials: YH
authors.lastname: Yang
authors.forename: Chun-Yuh
authors.initials: CY
authors.lastname: Yang
mesh_terms: D000368:Aged; D001932:Brain Neoplasms / Q000139:chemically induced / Q000401:mortality*; D002118:Calcium / Q000032:analysis; D016022:Case-Control Studies; D004326:Drinking; D005260:Female; D006801:Humans; D008274:Magnesium / Q000032:analysis; D008297:Male; D008875:Middle Aged; D009566:Nitrates / Q000032:analysis* / Q000592:standards / Q000633:toxicity; D016017:Odds Ratio; D012307:Risk Factors; D012959:Socioeconomic Factors; D013624:Taiwan / Q000453:epidemiology; D014874:Water Pollutants, Chemical / Q000032:analysis* / Q000592:standards / Q000633:toxicity; D014881:Water Supply / Q000032:analysis* / Q000592:standards
chemical_list: D009566:Nitrates; D014874:Water Pollutants, Chemical; D008274:Magnesium; D002118:Calcium