Chloral hydrate.

A concise assessment of the risks to human health and the environment posed by exposure to chloral hydrate, a chemical used in human and veterinary medicine as a sedative and hypnotic drug. Chloral hydrate and its metabolites are also formed as by-products when water is disinfected with chlorine.

Release to the environment occurs from wastewater treatment facilities, from the manufacture of pharmaceutical-grade chloral hydrate, and from the waste stream during the manufacture of insecticides and herbicides that use chloral hydrate as an intermediate. For the general public, the most important source of exposure is from treated drinking-water. When used as a pharmaceutical agent in humans, the chemical often causes gastric distress, nausea and vomiting at the recommended clinical dose. While persons surviving near-lethal acute overdoses show some signs of hepatic injury, no convincing evidence indicates that hepatic injury results from intake at the recommended dose.

Concerning kinetics and metabolism, studies show that chloral hydrate is completely absorbed and rapidly metabolized following oral administration. Laboratory studies of toxic effects found no evidence of behavioral changes, or of histopathological changes in nervous tissue. Limited data suggest that significant adverse effects on reproduction and development are unlikely. While some animal carcinogenicity studies show an increased risk of liver tumors, data were considered inadequate for an assessment of carcinogenic risk in humans. No long-term studies of exposed humans were available for evaluation. The report found no convincing evidence that exposure causes direct damage to DNA. Available data were judged inadequate to assess risks to the environment caused by chloral hydrate.