Human Exposure and Body Burden for Chloroform and Other Trihalomethanes

Abstract

ABSTRACTExisting information on human exposure to chloroform and other trihalomethanes (THMs) in air, water, and food is summarized. Three major surveys have collected data on chloroform levels in finished water at treatment plants. EPA's TEAM Studies have measured concentrations of THMs in residential drinking water and in personal, indoor, outdoor, and expired air from about 800 participants in eight cities. The Food and Drug Administration has surveyed chloroform levels in food and beverages. Recently, the Centers for Disease Control (CDC) have completed measuring blood levels of THMs in about 1000 participants in the National Health and Nutrition Examination Survey (NHANES).Exposure occurs through ingestion (drinking tap water and soft drinks and eating certain dairy foods), inhalation (breathing peak amounts of chloroform emitted during showers or baths, and lower levels in indoor air from other indoor sources), and dermal absorption (during showers, baths, and swimming). Each of these routes of exposure appear to be potentially substantial contributors to total exposure.The major source of exposure to chloroform is chlorination of water supplies. This results in exposure through ingestion of drinking water, but also through inhalation and skin absorption as a result of the myriad other uses of chlorinated water in the home: showers, baths, washing clothes and dishes, etc. Because chlorinated water supplies are used by bottling plants of soft drink manufacturers, even the chloroform found in beverages may be partially due to the chlorination of water supplies. Other sources of exposure, which can be important for specific groups of people, include chlorination of swimming pools, industrial production and use, and use of bleach during clothes washing.