Acute inhalation toxicity study of ammonia in rats with variable exposure periods.

The acute inhalation toxicity of ammonia was examined in rats using various exposure concentrations and exposure periods. Groups of male and female rats were exposed to dynamic atmospheres containing different concentrations of ammonia for 10, 20, 40 or 60 min. The aim of the study was to establish the relationship between exposure concentration and exposure period on the one hand and mortality on the other. The correlation between exposure concentration (c), exposure period (t) and mortality rate, expressed in probits was found to be Probit = 2.30 1 n [c2.20 x t] = 47.8 The following LC50 values for ammonia were calculated: 10 min LC50 : 28,130 mg/m3 air (40,300 ppm) 20 min LC50 : 19,960 mg/m3 air (28,595 ppm) 40 min LC50 : 14,170 mg/m3 air (20,300 ppm) 60 min LC50 : 11,590 mg/m3 air (16,600 ppm).