Chemistry International
Vol. 22, No.2, March 2000

2000, Vol. 22
No. 2 (March)
..News from IUPAC
..West Africa Chemical Society
..Reports from Symposia

..Awards and Prizes
..New Books
..Reports from Commissions
..Conference Announcements
..Conferences

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Chemistry International
Vol. 22, No. 2
March 2000

New Books and Publications

 

New Publication from the World Health Organization

Carbon Tetrachloride, Environmental Health Criteria No. 208

1999, xviii + 177 pages (English with summaries in French and Spanish), ISBN 92-4-157208-6, CHF 42.-/USD 37.80; In developing countries: CHF 29.40, Order No. 1160208.

This book evaluates the risks to human health and the environment posed by exposure to carbon tetrachloride, a volatile liquid previously used in the production of chlorofluorocarbons and other chlorinated hydrocarbons. Production and use have declined considerably following the Montreal Protocol on Substances that Deplete the Ozone Layer. Additional former applications that have also been phased out include use as a grain fumigant, pesticide, vent for oils and fats, metal degreaser, fire extinguisher, and flame retardant.

A review of data on the environmental behavior of this volatile chemical concludes that almost all carbon tetrachloride released to the environment is ultimately present in the atmosphere. Although estimates of atmospheric lifetime vary considerably, 45-50 years is accepted as the most reasonable range. Studies indicate significant global transportation and ubiquitous presence in air. The main degradation site is the stratosphere, where the chemical is photolytically degraded by ultraviolet radiation. Abundant evidence indicates that carbon tetrachloride contributes to both global warming and ozone depletion.

Concerning sources of exposure, studies of concentrations detected in a wide range of indoor and outdoor samples indicate that the general population can be exposed to carbon tetrachloride via air, food, and drinking-water. A review of studies of kinetics and metabolism in laboratory animals and humans cites evidence that carbon tetrachloride is well absorbed from the gastrointestinal and respiratory tracts and distributed throughout the body, with the highest concentrations detected in the liver, brain, kidney, muscle, fat, and blood.

A review of toxicity studies conducted in laboratory mammals and in vitro test systems indicates that the liver and kidney are the principal targets of toxic action. The severity of these toxic effects depends on a number of factors, including diet. Studies show that other compounds, including ethanol, can potentiate the hepatotoxicity of carbon tetrachloride. Long-term toxicity studies were judged inadequate to assess the chemical's carcinogenic potential. Carbon tetrachloride produced moderate irritation following skin application in animals.

An assessment of health effects in humans draws on findings from studies in human volunteers and case reports of accidental and suicidal poisoning. These findings confirm toxic effects on the liver and kidney. Acute symptoms of exposure include nausea, vomiting, headache, dizziness, dyspnea, and death. Liver damage appears after 24 hours or more, while kidney damage becomes evident only 2 to 3 weeks following acute exposure. Studies indicate that hepatic and renal damage can arise from long-term exposure to low concentrations. Available epidemiological studies have failed to establish an association between exposure to carbon tetrachloride and increased risk of mortality, neoplasia, or liver disease.

On the basis of this review, the report established a tolerable daily intake for carbon tetrachloride of 1.42 mg/kg body weight, and a tolerable daily concentration in air of 6.1 mg/m3.

 

 

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