A subchronic toxicity study of Fyrol PCF in Sprague-Dawley rats

Fyrol PCF is a flame retardant chemical widely used to control the flammability of rigid polyurethane foams and polyester foam systems. It has moderate acute toxicity and was shown to lack mutagenic activity. The present study was conducted to determine the toxicity of Fyrol PCF after repeated dietary exposure. Five groups, each consisting of 20 male and 20 female Sprague-Dawley rats, received a diet containing either 0, 800, 2500, 7500, or 20,000 ppm Fyrol PCF for 90 days. Data collected include clinical observations, food consumption, body weights, organ weights, urinalysis, hematology, clinical chemistry, brain cholinesterase activity, and gross and microscopic pathology. The mean body weight of animals receiving 20,000 ppm was significantly lower than control values for most study weeks. No clinical signs were noted during cage-side observations. Liver weights were increased in male rats in all treatment groups, and in female rats in both the mid- and high-dose groups. No treatment-related histopathologic changes were observed in the livers of animals that received 800, 2500, or 7500 ppm Fyrol PCF; however very mild periportal hepatocellular swelling was seen in certain of the 20,000 ppm animals. Mean kidney weights were significantly greater in the male animals given 2500, 7500, and 20,000 ppm. Very mild cortical tubular degenerative changes were found in kidneys of male rats that received 7500 ppm or 20,000 ppm and in female animals that ingested 20,000 ppm Fyrol PCF. An increase in the incidence of very mild thyroid follicular changes was found in the two highest dose groups. Fyrol PCF did not affect hematology or clinical chemistry parameters, nor did it significantly inhibit brain cholinesterase activity. None of the observed minimal treatment-related changes appear to have human relevance, because they occurred only at the highest doses used in the study. The no observable effect level in this study is 2500 ppm. Fyrol PCF demonstrated low subchronic toxicity in this study.