Synergistic toxicity of atrazine and organophosphate insecticides contravenes the response addition mixture model

摘要

A toxic unit (TU) approach was used to test the response addition model for mixtures of pesticides with differing modes of action. Atrazine was tested in binary and ternary combinations with the organochlorine insecticide methoxychlor and organo- phosphate insecticide methyl-parathion. Atrazine was also tested in binary combinations with additional organophosphates. The TU for atrazine was set slightly below its water solubility limits (TU = 20 ppm), which is well below its 96-h 50/100 effective Concentration for the fourth instar of the midge, Chironomus tentans.