Journal Article

Risk of Specific Birth Defects in Relation to Chlorination and the Amount of Natural Organic Matter in the Water Supply

Bing-Fang Hwang, Per Magnus and Jouni J. K. Jaakkola

in American Journal of Epidemiology

Published on behalf of Johns Hopkins Bloomberg School of Public Health

Volume 156, issue 4, pages 374-382
Published in print August 2002 | ISSN: 0002-9262
Published online August 2002 | e-ISSN: 1476-6256 | DOI:
Risk of Specific Birth Defects in Relation to Chlorination and the Amount of Natural Organic Matter in the Water Supply

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To assess the effect of water chlorination by-products on specific birth defects, the authors conducted a nationwide cross-sectional study of 285,631 Norwegian births in 1993–1998. Risks of birth defects according to four chlorination by-product exposure categories were compared on the basis of chlorination (yes/no) and level of water color (mg Pt/liter), representing the amount of natural organic matter: high (chlorination, ≤20), medium (chlorination, 10–19.9), and low (chlorination, <10) exposure, with no chlorination and low color (<10) as the reference category. In logistic regression analysis, the risks of any birth defect (adjusted odds ratio (OR) = 1.13, 95% confidence interval (CI): 1.01, 1.25) and of cardiac (adjusted OR = 1.37, 95% CI: 1.00, 1.89), respiratory system (adjusted OR = 1.89, 95% CI: 1.00, 3.58), and urinary tract (adjusted OR = 1.46, 95% CI: 1.00, 2.13) defects were significantly associated with exposure (medium and high combined). Regarding risk of specific birth defects, only that for ventricular septal defects was significantly elevated, with an exposure-response pattern, yielding adjusted odds ratios of 1.63 (95% CI: 1.02, 2.58) for the medium and 1.81 (95% CI: 1.05, 3.09) for the high exposure categories. Furthermore, risk of neural tube defects was related to high color (adjusted OR = 2.60, 95% CI: 1.30, 5.26).

Keywords: abnormalities; chlorine compounds; disinfection; water pollution, chemical; water purification; Abbreviations: CI, confidence interval; ICD-8, International Classification of Diseases, Eighth Revision; OR, odds ratio.

Journal Article.  5767 words. 

Subjects: Public Health and Epidemiology

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