Acute inhalation toxicology and proposed emergency exposure limits of nitrogen trifluoride.

Acute Inhalation Toxicology and Proposed Emergency Exposure Limits of Nitrogen Trifluoride. VERNOT, E. H., HAUN, C. C., MACEWEN, J. D. AND EGAN, G. F. (1973). Toxicol. Appl. Pharmacol. 26, 1-13. Acute exposures of rats, mice, dogs and monkeys to nitrogen trifluoride have been carried out and median lethal concentrations were determined for rats and mice. Confirmative evidence was obtained that the immediate effects of acute exposure are caused by extensive methemoglobin formation and resulting anoxia. Dogs surviving exposure to 9600 ppm for 60 min exhibit a Heinz body anemia with red blood cell count, hemoglobin and hematocrit decreasing 33 % to minimum values by the end of the second week postexposure. Recovery of hematologic values to preexposure levels is attained in 40 days. In dogs, the anemia caused by a dose level of 120,000 ppm-min is severe enough to invalidate that dose as an emergency exposure limit (EEL). At 30,000 ppm-min, however, no detectable anemia occurs, and no other toxic effects are discernible. The results of experiments conducted at subacute levels justify recommending an upward revision of the EEL to 30,000 ppm-min from the proposed National Academy of Science, National Research Council value of 3000 ppm-min.