Water disinfection by-products and the risk of specific birth defects: a population-based cross-sectional study in Taiwan.
BACKGROUND
Recent findings suggest that exposure to disinfection by-products may increase the risk of birth defects. Previous studies have focused mainly on birth defects in general or groups of defects. The objective of the present study was to assess the effect of water disinfection by-products on the risk of most common specific birth defects.


METHODS
We conducted a population-based cross-sectional study of 396,049 Taiwanese births in 2001-2003 using information from the Birth Registry and Waterworks Registry. We compared the risk of eleven most common specific defects in four disinfection by-product exposure categories based on the levels of total trihalomethanes (TTHMs) representing high (TTHMs 20+ microg/L), medium (TTHMs 10-19 microg/L), low exposure (TTHMs 5-9 microg/L), and 0-4 microg/L as the reference category. In addition, we conducted a meta-analysis of the results from the present and previous studies focusing on the same birth defects.


RESULTS
In multivariate logistic regression analysis the risk of ventricular septal defects (adjusted odds ratio 1.81, 95% confidence interval: 0.98 3.35), cleft palate (1.56. 95% CI: 1.00, 2.41), and anencephalus (1.96, 95% CI: 0.94, 4.07) were elevated in the high exposure compared to the reference category. In the meta-analysis, the summary odds ratio for ventricular septal defects (1.59, 95% CI: 1.21, 2.07) was consistently elevated.


CONCLUSIONS
The present study suggests that prenatal exposure to disinfection by-products increases the risk of ventricular septal defects, cleft palate, and anencephalus. The evidence on ventricular septal defects is consistent in the three available studies.
Hwang
Bing-Fang
BF
Department and Graduate Institute of Occupational Safety and Health, College of Public Health, China Medical University, No.91 Hsueh-Shih Road, Taichung 40402, Taiwan, ROC. bfhwang@mail.cmu.edu.tw
Jaakkola
Jouni Jk
JJ
Guo
How-Ran
HR
D000328:Adult; D000013:Congenital Abnormalities / Q000453:epidemiology / Q000209:etiology*; D003430:Cross-Sectional Studies; D004202:Disinfectants / Q000633:toxicity*; D004781:Environmental Exposure / Q000706:statistics & numerical data; D005260:Female; D006801:Humans; D007231:Infant, Newborn; D016015:Logistic Models; D008297:Male; D018811:Maternal Exposure / Q000009:adverse effects / Q000706:statistics & numerical data*; D015999:Multivariate Analysis; D016017:Odds Ratio; D011247:Pregnancy; D011297:Prenatal Exposure Delayed Effects / Q000453:epidemiology* / Q000209:etiology; D012189:Retrospective Studies; D018570:Risk Assessment; D012307:Risk Factors; D013624:Taiwan / Q000453:epidemiology; D022882:Trihalomethanes / Q000633:toxicity*; D014874:Water Pollutants, Chemical / Q000633:toxicity*; D018508:Water Purification; D014881:Water Supply / Q000032:analysis
D004202:Disinfectants; D022882:Trihalomethanes; D014874:Water Pollutants, Chemical