INHALATION TOXICITY OF PHOSPHINE IN THE RAT - ACUTE, SUBCHRONIC, AND DEVELOPMENTAL

Lethality is the primary hazard of phosphine exposures. All phosphine- related effects seen at sublethal exposure levels were relatively smal l and completely reversible either during the exposure or during a rec overy period Acutely, phosphine exposures were lethal to female Fische r 344 rats at a cumulative concentration-time product of about 180 ppm -hr if the concentration were greater than 5-7 ppm. For daily 6-hr exp osures, the median lethal times were 3 days at 10 ppm and 4 days at 7. 5 ppm. Thirteen daily 6-hr exposures to 5 ppm were not lethal. Decreas ed erythrocytes, lung congestion, and increased kidney weights with co agulative necrosis of the tubular epithelium in the outer cortex were seen in the 10 ppm rats only. The effects were more severe in females than in males. Subchronic exposures to 0.37, 1, or 3. 1 ppm of phosphi ne were conducted Ten animals per sex per group were sacrificed after 4 and 13 weeks of exposure and 4 weeks of recovery. These exposure pro duced a dose-related decrease in body weight gain at 1 and 3 ppm. Food consumption was decreased at 1 and 3 ppm and transiently in the 0.37 ppm group. Five percent decreases in erythrocytes, hemoglobin, and hem atocrit were seen in the 3 ppm group after 13 weeks of exposure. All e ffects seen in the subchronic study were completely reversible either during the 13-week exposure or the 4-week recovery period Exposure of pregnant CD(R) rats (24 per group) to 0.03, 0.33, 2.8, or 4.9 ppm of p hosphine for 6 hr/day over the days 6-15 gestation interval was not ma ternally or developmentally toxic.