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Last Edited: 11/9/2006

Semen Quality and Trihalomethanes in Drinking Water
Written: 2003


In 2003, the California Department of Health Services (CDHS) completed a study that looked at the relationship between semen quality and chemicals in drinking water.  Researchers looked at the amount of trihalomethanes in drinking water in relation to semen quality.the  count, concentration, movement, and shape of the sperm.

Trihalomethanes are a group of chemicals that are created when water is chlorinated. There are four different trihalomethanes.  Together they are called “total trihalomethanes” or TTHMs. The amount of TTHMs in drinking water can change over time, depending on the season, water temperature, and amount of chlorine needed to disinfect the water.

The study found that the amount of TTHMs did not lower the men’s sperm count or concentration. However, men who were exposed to higher levels of TTHMs had a slightly greater number of abnormally shaped sperm in one test.  The sperm from men with higher levels of BDCM also tended to have slightly more side-to-side motion, and slightly less forward motion.

EHIB does not believe that the very small changes we saw are harmful, or will lower men’s ability to have children. We are continuing to investigate the possible health effects of TTHMs in drinking water.

This fact sheet contains information about the study, as well as ways to lower your exposure to TTHMs in drinking water.

Click here to view the printable (pdf) version of the fact sheet (441KB)

Click here for the HTML version of the fact sheet