Abstract |
The influence of the commercial emulsifier on the acute toxicity and uptake of fenvalerate ((R,S)-a-cyano-3-phenoxybenzyl(R,S)-2-(4-chlorophenyl)-3-methylbutyrate), a synthetic pyrethroid insecticide, by fathead minnows (Pimephales promelas) was examined. Flow-through acute toxicity testing with measured concentrations of technical-grade fenvalerate and a 30% active ingredient emulsifiable concentrate (EC) of the insecticide was conducted. Steady-state LC50 values were reached by 72 and 120 to 168 h, respectively, in tests with technical-grade and EC formulations of this insecticide. Initially, technical-grade fenvalerate was more toxic; the 96-h LC50s for technical-grade fenvalerate and the EC were 0.69 and 0.99 micrograms/l, respectively. By 168 h, an LC50 of 0.75 micrograms/l was determined for the EC, indicating that the incipient lethalities of the two formulations were similar. (Copyright (c) 1985 SETAC.) |