ABSTRACT A petroleum-derived hydrocarbon mixture@ API No. 83-07@ was evaluated for its acute inhalation toxicity. In Phase I@ five young adult rats of each sex were exposed to a target aerosol concentration of 5.0 milligrams/liter (mg/L) for 4 hours. Since 2 animals died during the 14 day post exposure observation period@ Phase II was conducted in an attempt to define the LC50 of the test material aerosols. Five additional groups of 5 male and 5 female rats each were exposed to target concentrations from 0 (air only control) to 10 mg/L. Aerosol was generated using a DeVilbiss No. 40 nebulizer and administered in the breathing air of the animals atmosphere characterization tests@ it was shown that API No. 83-07@ when generated using this method@ produced an atmosphere that consisted entirely of aerosols. Analysis of aerosol concentration during animal exposure was performed gravimetrically and yielded time weighted average (TWA) concentrations of 5.38 mg/L (Phase I)@ 0.19@ 1.56@ 2.83@ 8.13 and 4.26 mg/L (Phase II). No animals died at the control and lowest test article concentration@ while all the animals exposed to the highest concentration died 2 to 3 days post-exposure. Individual and mean body weight gains were depressed in dose-related fashion following exposure to the test material. Histopathological examination of the lung tissues yielded dose-related morphological changes consistent with hydrocarbon toxicity. The LC50 could not be calculated for female rats. For combined males and females@ an LC50 value of 4.8 mg/L was estimated. Application of the Litchfield-Wilcoxon method yielded an LC50 of 3.35 mg/L for males@ with 95 per cent confidence limits of 2.5 to 4.5 mg/L.
API PUBL 33-30549-1986 history
1986API PUBL 33-30549-1986 ACUTE INHALATION TOXICITY EVALUATION IN RATS API 83-07 LIGHT CATALYTICALLY CRACKED DISTILLATE (CAS 64741-59-9)