of 320 mg/kg bodyweight. Toxicity following inhalation was not identified. Symptoms following acute exposure include cyanosis (blue or purple coloration of the skin due to low oxygen saturation in the tissue), increased methemoglobin levels and moderate skin irritation and severe eye irritation in rabbits. Short-term exposure Only oral short-term exposure in rats was researched of o-toluidine. Dermal exposure affected the ovarian cycle, ovary morphostructure, the ability to reproduce and the progeny in female rats when administered for four months (Malysheva and Zaitseva, 1982). Male rats treated similarly showed stimulated spermatogenesis (production of sperm cells) (Malysheva et al., 1983). Inhalation exposure was not identified. Rats were administered with the compound with a dose of 1125 mg/kg bodyweight over five days (225 mg/kg bodyweight per day). Observed symptoms included increased methemoglobin levels, congestion, hemosiderosis (iron overload disorder), hematopoiesis (formation of blood cellular components) in the spleen and a 1.5 to 3.0 times increase in spleen weight. Chronic exposure Chronic oral exposure to o-toluidine hydrochloride has induced increased incidences of tumors (benign and malignant) in rats and mice. In one study, rats were given doses of approximately 150 and 300 mg/kg bodyweight (low dose and high dose), a control-group was also present (NCI, 1979; Goodman et al., 1984). The exposure was associated with dose-related decrease in bodyweight gain, decrease in survival and with increased incidences of numerous types of cancer (sarcomas, angiosarcomas, fibrosarcomas, osteosarcomas, fibromas, fibroadenomas and mesothelioma). Non-neoplastic effects were also observed. These included hyperplasia (abnormal increase in volume of tissue), fibrosis (formation of excess fibrous connective tissue) and liver necrosis (premature death of cells in living tissue). Multiple other studies where rats or mice were given o-toluidine over a prolonged period of time had similar results, including but not limited to a decrease in survivability and increased incidences of different types of cancer (Hecht et al., 1982; Weisburger et al., 1978; NCI, 1979; Weisburger et al., 1978). Human exposure Acute human exposure to o-toluidine can cause painful hematuria (presence of red blood cells in the urine) (Goldbarb and Finelli, 1974). Chronic exposure to o-toluidine in humans was also observed in multiple retrospective cohort studies in the dyestuff industry. The results include increased incidence of death and increased incidence of bladder cancer. It proved difficult however to definitively link these to o-toluidine in due to the exposure to other expected carcinogenic compounds in the dyestuff industry. One study assessed the increased incidences