Acute toxicological effects in rats treated with a mixture of commercially formulated products containing methyl parathion and permethrin.
The study examined the interactions between a commercial formulation of methyl parathion (CF-MP) and a commercially formulated product of permethrin (CF-PMT) in male rats. The acute toxicity (LD50 values) and brain cholinesterase activity were investigated as toxicological endpoints. Results indicated that CF-MP modified the acute toxicity of CF-PMT. When animals were treated with a mixture, the addition of 380 mg/kg of CF-MP reduced the LD50 of CF-PMT by only 9.0%; however, when rats received CF-MP at 464 mg/kg, the LD50 of CF-PMT was reduced by 37% (P < 0.001). Also, CF-PMT decreased the CF-MP-induced inhibition of cholinesterase activity by 50% (P < 0.05). It was interesting to observe that xylene, which is the most abundant component in the vehicle of both formulations, had no effect on the CF-MP-induced inhibition of the cholinesterase activity. There was no relation between lethality and the inhibition of the brain cholinesterase activity in rats treated with mixtures containing CF-MP+CF-PMT or with either commercially formulated product alone. Considering the increased toxicity observed in rats treated with CF-PMT+CF-MP, it would be advisable to investigate further the interactions between both pesticides.
Ortiz
D
D
Laboratorio de Toxicología Ambiental, Facultad de Medicina, Universidad Autónoma de San Luis Potosí, Mexico.
Yáñez
L
L
Gómez
H
H
Martínez-Salazar
J A
JA
Díaz-Barriga
F
F
D000818:Animals; D001921:Brain / Q000187:drug effects* / Q000201:enzymology; D002800:Cholinesterase Inhibitors / Q000008:administration & dosage / Q000633:toxicity*; D002802:Cholinesterases / Q000032:analysis / Q000378:metabolism; D004357:Drug Synergism; D008401:Gas Chromatography-Mass Spectrometry; D007306:Insecticides / Q000008:administration & dosage / Q000633:toxicity*; D007928:Lethal Dose 50; D008297:Male; D008743:Methyl Parathion / Q000008:administration & dosage / Q000633:toxicity*; D026023:Permethrin; D011722:Pyrethrins / Q000008:administration & dosage / Q000633:toxicity*; D051381:Rats; D017208:Rats, Wistar
D002800:Cholinesterase Inhibitors; D007306:Insecticides; D011722:Pyrethrins; D008743:Methyl Parathion; D026023:Permethrin; D002802:Cholinesterases