Chlorination Byproducts and Nitrate in Drinking Water and Risk for Congenital Cardiac Defects

Exposure to chlorination byproducts in drinking water may result in increased congenital heart abnormalities. In Sweden, drinking water data for nearly 60,000 women was obtained. Of the more than 70,000 offspring of these women born between 1982 and 1996, 753 had cardiac defects. When surface and ground water sources were compared, initially it seemed that ground water ingestion increased risk of cardiac defects, but when other factors were considered, the risk factor turned out to be the procedures used for water disinfection, including chlorine dioxide. The odds ratio of bearing a child with a cardiac defect was 1.61 for those living in areas where drinking water was chlorinated with chlorine dioxide. As the concentrations of trihalomethanes increased in drinking water, the risk of cardiac defects increased. A nonsignificant increase in risk as nitrate concentrations increased was found. Although the individual risk remained small, the large population having exposure to chlorination byproducts means that the risk for cardiac defects cannot be considered to be negligible.