Lung toxicity chloroform

The metabolism of chloroform is well understood. Approximately 50% of an oral dose of 0.5 grams of chloroform was metabolized to carbon dioxide in humans (Fry et al. 1972). Metabolism was dose-dependent, decreasing with higher exposure. A first-pass effect was observed after oral exposure (Chiou 1975). Approximately 38% of the dose was converted in the liver, and < 17% was exhaled unchanged from the lungs before reaching the systemic circulation. On the basis of pharmacokinetic results obtained in rats and mice exposed to chloroform by inhalation, and of enzymatic studies in human tissues in vitro, in vivo metabolic rate constants (V, 3,C =15.7 mg/hour/kg, = 0.448 mg/L) were defined for humans (Corley et al. 1990). The metabolic activation of chloroform to its toxic intermediate, phosgene, was slower in humans than in rodents. 

Hydrocyanic acid was used in large quantities by the French as a war-gas in shells. A mixture of the acid with stannic chloride and with chloroform, which was added to prevent polymerization and to increase the density of the vapor, was known as vincennite. It was shown during the latter part of the war that hydrocyanic acid was efficient only when a certain minimum concentration was obtained. Up to this concentration hydrocyanic acid can be breathed without serious effect above it the gas is quickly fatal. As it was difficult to obtain in the open field the required toxic concentration, the use of the gas was abandoned for others that were cumulative in their effect. These gases when breathed even in very low concentrations accumulated in the lungs and finally produced their toxic effect. 

Properties Colorless clear liq., benzene odor sol. in alcohol, benzene, ether, acetone, chloroform, petrol, ether, ethyl acetate misc. with most org. soivs. very si. sol. in water m.w. 92.13 dens. 0.866 (20/4 C) vapor pressure 36.7 mm Hg (30 C) m.p. -94.5 C b.p. 110.7 C flash pt. (CC) 4.4 C ref. index 1.4967 (20 C) KB value 105 Toxicology ACGIH TLV/TWA 100 ppm STEL 150 ppm LD50 (oral, rat) 7.53 g/kg, (skin, rabbit) 12,124 mg/kg toxic by ing., inh., IP, and skin absorption irritant to eyes, skin, respiratory tract severe dermatitis on direct contact ing. may cause lung aspiration overexposure by inh. may cause CNS excitation/depression high cones, may cause paresthesia, vision disturbances, dizziness, nausea, headache, narcosis, death experimental teratogen. 

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