Health Concerns

Carbon Tetrachloride

Carbon tetrachloride enters the body through the lungs, stomach, intestines and skin. About 60% of the carbon tetrachloride inhaled by humans is believed to be absorbed into the body. It is not known whether this relationship is applicable to low level exposures such as is found in the ambient air.

Most of the inhaled carbon tetrachloride that enters the body is temporarily accumulated in body fat. Some of the carbon tetrachloride can enter the kidney, liver, brain, lungs and skeletal muscle. Once it is transported to the liver by the blood it is transformed through metabolic processes to the toxic form. Because of this biotransformation in the body, toxic responses to carbon tetrachloride can be severely increased by drugs and chemicals. Chemical interactions between carbon tetrachloride and alcohol can be fatal.

Much of the carbon tetrachloride that enters the body through inhalation quickly leaves the body through exhaled air. Animal studies also suggest that it may take weeks for the remainder of the compound in the body to be eliminated, especially that which has entered the body fat. Although most of the carbon tetrachloride is eliminated from the body unchanged, some may change to other chemicals (for example, chloroform, hexachloroethane, and carbon dioxide). Chloroform and hexachloroethane may themselves cause harmful effects (ATSDR, 1994).

Most of the information on health effects of carbon tetrachloride in humans comes from cases where people have been exposed to relatively high levels of carbon tetrachloride, either only once or for a short period of time. Exposure to carbon tetrachloride in the environment may produce effects on the liver, kidney and brain. In severe cases, liver cells may be damaged or destroyed, leading to a decrease in liver function. Kidney failure often was the main cause of death in people who died after very high exposure to carbon tetrachloride. After exposure to high levels of carbon tetrachloride, the nervous system, including the brain, is affected. Such exposure can be fatal. The immediate effects are usually signs of intoxication, including headache, dizziness, and sleepiness perhaps accompanied by nausea and vomiting. In severe cases, stupor or even coma can result, and permanent damage to nerve cells can occur. In animals, the compound has produced cancer in various organs. The effects of carbon tetrachloride are reversible over periods of several days to a week or more. Repeated exposures would be expected to increase the toxicity experienced over a short term. Therefore, children, the elderly, and persons with liver or kidney disease are especially at risk from exposures.

Carbon tetrachloride is also found in drinking water supplies and household products. The effects of these multiple exposures would be additive to that found in the air and may be greater.

Carbon tetrachloride has been classified as Class B2: Probable Human Carcinogen by the United States Environmental Protection Agency and as a Group 2B: Possible Human Carcinogen by the International Agency for Research on Cancer.

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Last Updated: 1/31/03