Acute toxicity in rats of chlorinated hydrocarbons given via the intratracheal route.

1. The approximate lethal dose (ALD) of six chlorinated hydrocarbons via the intratracheal route has been determined in rats and compared with published oral LD50 values. 2. The compounds tested in this study were dichloromethane, perchloroethylene, trichloroethylene, carbon tetrachloride, chloroform and ethylene dichloride. 3. A method of administering the materials intratracheally to unanaesthetized animals was developed. 4. The intratracheal ALD of the chlorinated hydrocarbons ranged from 3.1 to 17.5% of the oral LD50 and death was peracute. 5. Aspiration of chlorinated hydrocarbons may present more of a hazard than oral toxicity and should be considered when rendering first aid or emergency medical treatment.