Petroleum hydrocarbon toxicity studies: XII. Animal and human response to vapors of “40 Thinner”

Abstract

The suggested hygienic standard for “40 Thinner”, based upon the results of inhalation studies with rats and dogs and the sensory response of human subjects, is 0.15 mg/liter (25 ppm). Rats tolerated 0.20 mg/liter (33 ppm) and dogs 0.25 mg/liter (41 ppm) for 7 and 8 hr, respectively, without visible discomfort. Inhalation by rats for 7 hr of a <1-μm aerosol at a concentration of 8.3 mg/liter resulted in irritation of the extremities and slight loss of coordination. Three cats inhaled a similar aerosol at a concentration of 7.0 mg/liter for 6 hr without visible discomfort. After inhaling a vapor concentration of 0.22 mg/liter (36 ppm) for 6 hr per day, 5 days per week, neither rats nor dogs were statistically significantly different from their controls in any criterion of effect after 13 weeks of inhalation. The odor threshold, as determined by a sniff test involving six human subjects, is approximately 0.001 mg/liter (0.17 ppm). Mild discomfort was reported by a group of six human subjects following a 15-min inhalation period in 0.21 mg/liter (35 ppm) but none was reported at 0.10 mg/liter (17 ppm). It is anticipated, therefore, that 0.15 mg/liter (25 ppm) would be tolerable for daily 8-hr inhalation in the work-room atmosphere.