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.