The Journal of toxicological sciences
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Chronic toxicity and carcinogenicity of polyoxyethylene(10)nonylphenyl ether (NP-10) to Fischer 344 rats were investigated using 70 females per group in 4 study groups, or 280 rats in total. Diets containing NP-10 at 0, 1000, 3000 and 9000 ppm were prepared and orally administered to the animals repeatedly for 52 weeks for a chronic toxicity study and for 104 weeks for a carcinogenicity study. Observations of general condition, body weight analysis, food consumption analysis, hematologic examination, blood chemistry examination (only at Week 52 of administration), urinalysis (only at Week 52), ophthalmologic examination (immediately prior to administration and at Week 52), organ weight analysis and pathological examination were performed. ⋯ In the histological findings, bile duct hyperplasia of liver in the animals killed at Week 52, proliferative duct of pancreas in the animals killed at Week 104, pigment of deposit in pituitary and angiectasis of adrenals in the animals killed at moribund and dead animals were observed in a slightly larger number in the treated groups, but none of these changes were different in degree from the control and were not considered to be specific lesions. As a result of the overall study of the neoplastic lesions of all animals killed on schedule and of moribund and dead animals, no tumors were found in the treated groups which had increased in occurrence. Based on the above findings, it was determined that the no-adverse-effect level in the chronic toxicity study was 1000 ppm (