Subchronic Toxicity Studies of 2,4,6-Trichlorophenol in Sprague-Dawley Rats

2,4,6-Trichlorophenol (TCP) has been found in drinking water as a result of its use as a fungicide and due to its inadvertent production in the water purification process. This study was conducted since information on the toxicity from repeated ingestion was inadequate. Male and female Sprague-Dawley rats were gavaged with TCP administered in corn oil (2 ml/kg body weight) for 90 consecutive days at dose levels of 0, 80, 240, and 720 mg/kg per day. Treatment-related effects were observed at the highest dose (720 mg/kg/day) and consisted of salivation, urine stains on the fur, increase in absolute and relative weights of the kidneys, liver, adrenal glands, and testes. At this dose, increases were seen in serum protein, albumin, and alanine aminotransferase (ALT), with a decrease in urinary pH. Some effects observed at 240 mg/kg per day were an increase in the absolute and relative weights of the liver and adrenal glands in females, relative liver weights in males, and an increase in serum albumin in males. No treatment-related effects were observed at 80 mg/kg per day. No mortality or significant effects were observed at any dose level for body weight, food consumption, ophthalmic lesions, hematology, gross pathology, or histopathology. Based on clinical chemistry and organ weight changes, it appears that the liver, kidney, and adrenal glands were target organs for systemic toxicity to TCP in this study, although this was not correlated with histopathology lesions. It was concluded that 240 mg/kg/day represents a lowest observed adverse effect level (LOAEL), although the toxic effects were minimal. The no observed adverse effect level (NOAEL) for subchronic exposure to TCP by the oral route was 80 mg/kg per day.