Sdudy on Subchronic Toxicity of Fipronil in Rats

Objective To study the subchronic toxicity of fipronil in rats and to protect and improve the environment and human health. Methods 80 SD rats were randomly divided into four groups,20 in each groups (10 males and 10 females). The rats were treated with fipronil by gavage,in doses of 25,10,4,0 mg/kg,once a day,10 ml/(kg·d),for 90 consecutive days. The test method was according to GB15670—1995. Results The acute toxicity symptom of rats in high dose showed that cachexia,dull,hair floppy. No acute toxicity symptoms were found in the moderate and low dose groups. No significant difference was found in the serum and urine routine test indexes. Liver index increased significantly in the high dose(25 mg/kg)and moderate dose(10 mg/kg) exposed rats. The activity of aspartateaminotransferase (AST) in the serum increased only in male rats. No significant changes in indicators were found in the low exposed rats. The histopathologic examination showed that in the high and moderate dose groups,in the liver,spot and focus necrosis,the hepatocytes around central veins became bigger and cloudy swelling,some hepatocytes presented ballooning degeneration. No obvious pathological change was seen in the low dose group. Conclusion Fipronil has a toxicity to the liver,based on 90 day oral toxic test in rats,no-observed adverse effect level (NOAEL) is 4 mg/(kg·d).