Abstract
Groups of 21 male and 21 female Sprague-Dawley (SD) rats were fed diets containing pyriproxyfen at concentrations of 0, 80, 400, 2, 000 and 10, 000ppm for 6 months. No death was found in any group. Alopecia in the neck and/or back, and soft feces were noticed in both sexes fed 10, 000ppm. A marked decrease in body weight gain was observed in both sexes fed 10, 000ppm throughout the treatment period, accompanying a decrease in food-consumption and an increase in water-intake during the initial stage of treatment. In terms of urinalysis, proteinuria, increases in K excretion, and, in number, yellowness or browish-yellowness in appearance, were observed in both sexes fed 10, 000ppm. In females fed 10, 000ppm, increases in bilirubin, Na excretion and specific gravity, and a decrease in keton bodies, were observed. In hematology, decreases in erythrocyte count, bemoglobin concentration and hematocrit value, were observed in both sexes fed 10, 000ppm and in males fed 2, 000ppm. Also, an increase in MCH (in males), decreases in MCHC and platlet count (in females) were observed in 10, 000ppm group. Blood biochemistry revealed increases in total protein, albumin, α 2-globulin fraction, blood urea nitrogen, calcium (in both sexes fed 10, 000ppm), A/G ratio (in males fed 2, 000 and 10, 000ppm), total cholesterol, phospholipid (in males fed 2, 000 and 10, 000ppm, and in females fed 10, 000ppm), sodium (in females fed 2, 000 and 10, 000ppm), γ-glutamyl transpeptidase activity (in males fed 10, 000ppm) and α1-globulin fraction (in females fed 10, 000ppm), and decreases in glucose, GOT (in both sexes fed 10, 000ppm), β-globulin fraction (in males fed 2, 000 and 10, 000ppm, and in females fed 10, 000ppm), GPT (in females fed 2, 000 and 10, 000ppm), triglyceride, potassium (in males fed 10, 000ppm), and cholinesterase activity (in female fed 10, 000ppm). In organ weight, increases in liver (in males fed 2, 000 ppm and 10, 000ppm, and in females fed 10, 000ppm), kidney (in both sexes fed 10, 000ppm) and thyroid (in females fed 10, 000ppm) and a decrease in pituitary (in females fed 2, 000 and 10, 000ppm) were observed. Gross patholoty revealed a higher incidence of blackish-brown coloration of the liver, and a lower incidence of accentuated lobular pattern of the liver (in males fed 10, 000ppm). An enlargement of the liver was seen in a few of both sexes fed 10, 000ppm. Histopathological examination showed that the sole effect attributable to treatment of this compound was on slight hypertrophy in the liver of both sexes fed 10, 000ppm, with a higher incidence. Based on the above results, pyriproxyfen administered to SD rats for 6 months revealed slight toxic effects such as an increased liver weight associated with hypertrophy of hepatocyte and an increased kidney weight at the highest dose level at which body weight gain was clearly suppressed. It is coricluded that the non-effective level is 400ppm for both sexes (24.0mg/kg for males, 27.5mg/kg for females).
