What are THMs?
THMs are a group of chemicals that are created when water is chlorinated. When drinking water is disinfected with chlorine, over time the chlorine mixes with organic matter in the water (such as leaf debris) and creates other chemicals called by-products. THMs are one of the by-products of chlorinating water. There are four different trihalomethanes: bromoform, chloroform, bromodichloromethane, and chlorodibromomethane. 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, amount of chlorine needed to disinfect the water, and other factors. How was the study done? CDHS enrolled 157 men in this study. The men were the husbands of women who participated in a companion study of TTHMs and menstrual cycles1. Between May 1990 and June 1991, the men completed an interview, which included questions on how much tap water they drank at home and provided two semen samples. During this time,
