Inhalation toxicity of dehydrothio-p-toluidine

The acute inhalation toxicity of dehydrothio -p-toluidine ( DHPT ; CAS Registry No. 92-36-4) was determined by exposing groups of young adult Crl-CD rats for single 4-hr periods. Death resulted when the DHPT concentration reached 3.00 mg/litre. The subchronic effects of DHPT were studied by exposing male rats to 0.6 mg/litre for ten 6-hr periods (five exposure days, two rest days, five exposure days). Body-weight loss during the exposures was followed by normal weight gain during a 14-day recovery period. Salivation, lachrymation , pawing and chewing motions, rapid respiration and red nasal discharge occurred during exposure and continued into the recovery period, although they generally abated as the recovery period progressed. Clinical laboratory measurements on blood from exposed rats suggested a haemolytic anaemia with injury to the liver and kidneys. Liver changes were characterized by hepatocyte hypertrophy and proliferation of bile-duct epithelial cells. A mild degree of renal tubular degeneration was seen and the spleen showed congestion of red pulp with excessive amounts of haemosiderin. These effects persisted throughout the 2-wk recovery period.