HUMAN EXPOSURE AND BODY BURDEN FOR CHLOROFORM AND OTHER TRIHALOMETHANES

Existing information on human exposure to chloroform and other trihalo methanes (THMs) in air, water, and food is summarized. Three major sur veys have collected data on chloroform levels in finished water at tre atment plants. EPA's TEAM Studies have measured concentrations of THMs in residential drinking water and in personal, indoor, outdoor, and e xpired air from about 800 participants in eight cities. The Food and D rug Administration has surveyed chloroform levels in food and beverage s. Recently, the Centers for Disease Control (CDC) have completed meas uring blood levels of THMs in about 1000 participants in the National Health and Nutrition Examination Survey (NHANES). Exposure occurs thro ugh ingestion (drinking tap water and soft drinks and eating certain d airy foods), inhalation (breathing peak amounts of chloroform emitted during showers or baths, and lower levels in indoor air from other ind oor sources), and dermal absorption (during showers, baths, and swimmi ng). Each of these routes of exposure appear to be potentially substan tial contributors to total exposure. The major source of exposure to c hloroform is chlorination of water supplies. This results in exposure through ingestion of drinking water, but also through inhalation and s kin absorption as a result of the myriad other uses of chlorinated wat er in the home: showers, baths, washing clothes and dishes, etc. Becau se chlorinated water supplies are used by bottling plants of soft drin k manufacturers, even the chloroform found in beverages may be partial ly due to the chlorination of water supplies. Other sources of exposur e, which can be important for specific groups of people, include chlor ination of swimming pools, industrial production and use, and use of b leach during clothes washing.