Acute toxicological effects in rats treated with a mixture of commercially formulated products containing methyl parathion and permethrin

Ecotoxicol Environ Saf. 1995 Nov;32(2):154-8. doi: 10.1006/eesa.1995.1096.

Abstract

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.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Brain / drug effects*
  • Brain / enzymology
  • Cholinesterase Inhibitors / administration & dosage
  • Cholinesterase Inhibitors / toxicity*
  • Cholinesterases / analysis
  • Cholinesterases / metabolism
  • Drug Synergism
  • Gas Chromatography-Mass Spectrometry
  • Insecticides / administration & dosage
  • Insecticides / toxicity*
  • Lethal Dose 50
  • Male
  • Methyl Parathion / administration & dosage
  • Methyl Parathion / toxicity*
  • Permethrin
  • Pyrethrins / administration & dosage
  • Pyrethrins / toxicity*
  • Rats
  • Rats, Wistar

Substances

  • Cholinesterase Inhibitors
  • Insecticides
  • Pyrethrins
  • Methyl Parathion
  • Permethrin
  • Cholinesterases