Research

Water disinfection by-products and the risk of specific birth defects: a population-based cross-sectional study in Taiwan

Bing-Fang Hwang^1,2,3 , Jouni JK Jaakkola⁴ and How-Ran Guo²

¹  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

²  Department of Occupational and Environmental Medicine, National Chung Kung University, No. 138 Sheng-Li Road, Tainan 70428, Taiwan, ROC

³  Department of Health Care Administration, Diwan College of Management, No. 87-1 Nan-Shih Li, Tainan 72153, Taiwan, ROC

⁴  The Institute of Occupational and Environmental Medicine, The University of Birmingham, Edgbaston, Birmingham B15 2TT, UK

author email corresponding author email

Environmental Health 2008, 7:23doi:10.1186/1476-069X-7-23

Published:	2 June 2008

Abstract

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+ μg/L), medium (TTHMs 10–19 μg/L), low exposure (TTHMs 5–9 μg/L), and 0–4 μg/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.

Conclusion

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.