Epidemiological studies on cancer and organic compounds in U.S. drinking waters.

Two national surveys of U. S. drinking waters have been conducted to determine the presence and concentration levels of organic compounds, particularly trihalomethanes. Most drinking water supplies from surface water sources have been shown to contain numerous organic compounds at very low levels. Chloroform is present in virtually all drinking water supplies that are treated with chlorine as a disinfectant. The health effects of organic compounds have been investigated by animal and epidemiological studies. Numerous epidemiological studies have been conducted on various geographic sections of the United States. Fourteen epidemiological studies that were hypothesis generating studies were conducted to determine if there is a positive association between drinking water and increased cancer mortality. These studies may indicate which organ(s) might potentially be the affected organ(s). Further epidemiological studies that tested various hypotheses were conducted. A summary of these studies is presented, which indicates that there is potentially an increased risk of bladder, colon, and rectum cancer from drinking waters containing trihalomethanes.