Chronic Toxicity and Carcinogenic Potential of Tris-(1,3-Dichloro-2-propyl) Phosphate in Sprague-Dawley Rat

Abstract

The Flammable Fabrics Act of 1953 and its amendments established a need for flame-resistant fabrics. Tris-(1,3-dichloro-2-propyl) phosphate (TDCPP) was briefly used in apparel fabrics to assist in the compliance with federal flammability standards, and continues to be used as a flame retardant in flexible polyurethane foams. A chronic toxicity and carcinogenicity bioassay was conducted in Sprague-Dawley rats to determine the toxicologic and carcinogenic potential of TDCPP after repeated exposure. Four groups of animals, each consisting of 60 male and 60 female rats, received via their diet a daily dose of either 0, 5, 20, or 80 mg TDCPP per kg body weight for up to 24 months. Diets were adjusted after each weekly (first 13 weeks) or biweekly (weeks 14 through 104) body weight and food consumption measurement to achieve and maintain the indicated doses. Ten animals per sex were taken from each group for interim sacrifice at the end of the 12th month. Body weights, food consumption, clinical signs, and hematological and clinical chemistry parameters were measured periodically, and ophthalmoscopic examinations were conducted on all animals. After complete postmortem examination of all animals, microscopic examination of all tissues was conducted for the control and high-dose animals. Liver, kidneys, testes, and adrenal glands were examined from all animals. Mortality was significantly higher and body weights were significantly lower in the high-dose group when compared to control animals. Certain hematology parameters, such as hemoglobin, hematocrit, and total erythrocyte values, were decreased in the high-dose animals. Ophthalmoscope examination revealed no treatment-related changes. Microscopic examination revealed a higher incidence of benign neoplasms and non-neoplastic alterations in several organs of the mid and high dose animals. The no-observed-adverse-effect level (NOAEL) for chronic toxicity and neoplastic activity was the dietary dose of 5 mg/kg/day.