Chlorination of surface water to make it into drinking water may raise risks for birth defects, according to results of a study conducted in Norway. Chlorination of drinking water that contains organic compounds leads to the formation of by-products, some of which have been shown to have mutagenic (mutation-causing) or carcinogenic effects. They report that overall risk for birth defects rose by 14% in municipalities with both chlorinated water and water with relatively high concentrations of organic material, compared with municipalities with no chlorination and low levels of organic material. Chlorination-associated risks for urinary tract birth defects were especially high. Babies born in areas with high levels of chlorination/organic content faced double the risk of these types of malformations compared with infants born in areas without chlorinated water, according to the researchers. They add that risks for serious neural tube defects (such as spina bifida) rose 26% in babies born in chlorinated areas versus those born in non-chlorinated municipalities.  

Epidemiology September 1999;10:513-517. 

COMMENT: It is very important to have a filter on your water system. If you have a water softener, you will need a reverse osmosis system to remove the harmful salt. This is true even if you use potassium chloride rather than sodium chloride.  It is also important to have a filter for your shower. As mentioned in a previous newsletter, unfiltered municipal (non-well water) is the largest source of indoor air pollution.