effects. However, the effects are not disabling and are transient and reversible upon cessation of exposure.

AEGL-2 is the airborne concentration (expressed as ppm or mg/m3) of a substance above which it is predicted that the general population, including susceptible individuals, could experience irreversible or other serious, long-lasting adverse health effects or an impaired ability to escape.

AEGL-3 is the airborne concentration (expressed as ppm or mg/m3) of a substance above which it is predicted that the general population, including susceptible individuals, could experience life-threatening health effects or death.

Airborne concentrations below the AEGL-1 represent exposure concentrations that could produce mild and progressively increasing but transient and nondisabling odor, taste, and sensory irritation or certain asymptomatic, nonsensory effects. With increasing airborne concentrations above each AEGL, there is a progressive increase in the likelihood of occurrence and the severity of effects described for each corresponding AEGL. Although the AEGL values represent threshold concentrations for the general public, including susceptible subpopulations, such as infants, children, the elderly, persons with asthma, and those with other illnesses, it is recognized that individuals, subject to idiosyncratic responses, could experience the effects described at concentrations below the corresponding AEGL.

SUMMARY

Chloroform is a volatile liquid with a pleasant, nonirritating odor. The chemical is miscible with organic solvents but is only slightly soluble in water. Chloroform is produced and imported in large quantities for use in chemical syntheses, as a solvent, and in the manufacture of some plastics. It was used in the past as an anesthetic and in pharmaceutical preparations, but such uses are no longer allowed in the United States.

Human data on acute exposure to chloroform are from older studies that tested various exposure regimens (680-7,200 ppm for 3-30 min); effects included detection of a strong odor, headaches, dizziness, and vertigo. Published reports of surgical patients anesthetized with chloroform lack precise exposure details, but suggest that exposure to high concentrations (generally greater than 13,000 ppm) might produce cardiac arrhythmias and transient hepatic and renal toxicity. Quantitative data on human fatalities after acute inhalation exposure to chloroform were not available.

Only a few animal studies on the lethality from acute exposure to chloroform were available. Quantitative data include a 4-h LC50 (lethal concentration, 50% lethality) of 9,780 ppm in rats and a 7-h LC50 of 5,687 ppm in mice. Other data indicate notable lethality after exposures ranging from 5 min at “saturated” concentration (approximately 25,000 ppm) to 12 h at 726 ppm. Nonlethal effects of chloroform in laboratory animals include biochemical (elevated serumenzyme



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