Lack of promoting activity of four pesticides on induction of preneoplastic liver cell foci in rats.
Four pesticides were examined for hepatopromoting activity using a medium-term bioassay based upon induction of glutathione S-transferase placental form (GST-P) positive foci in the rat liver. Male F344 rats were initially injected with diethylnitrosamine (DEN; 200 mg/kg body weight) intraperitoneally and 2 weeks later were treated with O-ethyl O-4-nitrophenyl phenylphosphonothioate (EPN; 75 and 150 ppm), diazinon (500 and 1,000 ppm), phenthoate (500 and 1,000 ppm), or iprobenfos (500 and 1,000 ppm) in the diet for 6 weeks and then killed, all rats being subjected to partial hepatectomy at week 3. All of the pesticides gave negative results, the numbers and areas of GST-P positive foci not exceeding the control values for animals given DEN alone. Indeed, a significant reduction of foci development was seen for EPN (75 ppm). These findings provide experimental evidence that the presently examined four pesticides do not have hepatocarcinogenic potential in rats.
Kato
T
T
First Department of Pathology, Nagoya City University Medical School, Nagoya, Japan.
Ogiso
T
T
Kato
K
K
Sano
M
M
Hasegawa
R
R
Shirai
T
T
Ito
N
N
D000818:Animals; D002273:Carcinogens / Q000633:toxicity*; D003976:Diazinon / Q000633:toxicity; D004052:Diethylnitrosamine; D008114:Liver Neoplasms, Experimental / Q000139:chemically induced*; D008297:Male; D009946:Organothiophosphorus Compounds / Q000633:toxicity; D010575:Pesticides / Q000633:toxicity*; D004849:Phenylphosphonothioic Acid, 2-Ethyl 2-(4-Nitrophenyl) Ester / Q000633:toxicity; D011230:Precancerous Conditions / Q000139:chemically induced*; D051381:Rats; D011916:Rats, Inbred F344
D002273:Carcinogens; D009946:Organothiophosphorus Compounds; D010575:Pesticides; D004849:Phenylphosphonothioic Acid, 2-Ethyl 2-(4-Nitrophenyl) Ester; D004052:Diethylnitrosamine; C008838:phenthoate; D003976:Diazinon