Journal of Water and Health Vol 9 No 3 pp 498506 © IWA Publishing 2011 doi:10.2166/wh.2011.006
Does calcium in drinking water modify the association between nitrate in drinking water and risk of death from colon cancer?
Hui-Fen Chiu, Shang-Shyue Tsai, Pei-Shih Chen, Trong-Neng Wu and Chun-Yuh Yang
Department of Pharmacology, Kaohsiung Medical University, Kaohsiung, Taiwan
Department of Healthcare Administration, I-Shou University, Kaohsiung County, Taiwan
Faculty of Public Health, College of Health Sciences, Kaohsiung Medical University, Kaohsiung, Taiwan E-mail: email@example.com
Graduate Institute of Environmental Health, China Medical University, Taichung, Taiwan
Division of Environmental Health and Occupational Medicine, National Health Research Institute, Miaoli, Taiwan
The objective of this study was to explore whether calcium (Ca) levels in drinking water modified the effects of nitrate on colon cancer risk. A matched casecontrol study was used to investigate the relationship between the risk of death from colon cancer and exposure to nitrate in drinking water in Taiwan. All colon cancer deaths of Taiwan residents from 2003 through 2007 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 the cases by gender, year of birth and year of death. Information on the levels of nitrate-nitrogen (NO3-N) and Ca in drinking water have been collected from Taiwan Water Supply Corporation (TWSC). The municipality of residence for cases and controls was assumed to be the source of the subject's NO3-N and Ca exposure via drinking water. We observed evidence of an interaction between drinking water NO3-N and Ca intake via drinking water. This is the first study to report effect modification by Ca intake from drinking water on the association between NO3-N exposure and risk of colon cancer mortality.
Keywords: calcium; colon cancer; drinking water; effect modification; nitrate
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