Subchronic toxicity study of 1,2,4-trichlorobenzene in the rat, rabbit and beagle dog

Trichlorobenzenes: results of a thirteen week feeding study in the rat

Trichlorobenzenes (TRCBs) are industrial chemicals and environmental pollutants found in Great Lakes fish. The present study was carried out to provide information on the toxic effects of these chemicals in mammals. Groups of male and female weanling rats were fed diets containing TRCB isomers at 1, 10, 100 or 1000 ppm for 13 weeks. The group of males fed 1000 ppm 1,2,3-TRCB diet had reduced weight gain. No other clinical signs of toxicity were observed. Increased relative liver and kidney weights occurred in the highest dose groups of males for all 3 TRCBs. Of the 3 isomers, only 1,2,4-TRCB at 1000 ppm caused increases in hepatic aminopyrine demethylase and aniline hydroxylase activities in male rats, and aminopyrine demethylase in females. Serum biochemical and hematological parameters measured were not affected. All three TRCBs produced histological changes of a moderate degree in the liver and thyroid of male rats at 1,000 ppm. Only 1,3,5-TRCB elicited moderate renal changes in male rats fed 1,000 ppm. Microscopic changes in the females were generally milder than those of the corresponding males. Based on these data it was concluded that the nonobservable adverse effect levels for the three TRCBs were 100 ppm in the diet, or 7.6 approximately 7.8 mg/kg b.w./day depending on the dietary consumption.

Subchronic inhalation toxicity of 1,3,5-trichlorobenzene

Male and female rats were exposed to 0, 10, 100 or 1000 mg/m3 of 1,3,5-trichlorobenzene vapors for 6 hours daily, 5 days a week, for up to 13 weeks. After 4 and 13 weeks of exposure, animals were sacrificed and examined for changes in blood, clinical chemistry, internal organs, and tissues resulting from the 1,3,5-trichlorobenzene treatment. No treatment-related effects on the blood and clinical chemistry were evident. The only effects that were considered treatment-related were a squamous metaplasia and hyperplasia in the respiratory epithelium in the nasal passages of high-dose rats and the increased incidence of dried red material on the faces of these rats during exposures compared with other groups.

Subchronic dermal toxicity study of trichlorobenzene in the rabbit

Groups of five male and five female New Zealand albino rabbits were treated by skin application with either 0 (distilled water control), 30, 150 or 450 mg/kg undiluted trichlorobenzene (ICB) for 5 days/week for four weeks. No treatment related systemic effects were observed at any of the treatment levels when body weight, clinical chemistry and organ weight parameters were measured. Systemic effects due to dermal application of TCB were present only in rabbits given 450 mg/kg/day. These effects included a slight but statistically significant increase in the urinary coproporphyrin excretion in males and slight pallor of the liver at gross necropsy in both sexes. Localized effects at the site of application were present in all treated rabbits. These effects were characteristic of the response to dermal irritation. Grossly, the fur was matted by a fine white bran-like scales with variable degrees of erythema, fissures, erosions and ulcers. Histopathologically, there was inflammation and thickening of the epidermis. The size of the affected area varied directly with the dose level. Based on the results of the study, it was concluded that a dose level of 450 mg/kg/day of TCB applied dermally to rabbits induced slight systemic toxicity. The no-observable effect level for systemic toxicity was 150 mg/kg/day when TCB was applied to the skin of male and female rabbits over the course of 30 days.