PW09 Pesticide I
8:00 AM - Wednesday
(PW156) Temporal variation in mixture toxicity of organophosphate insecticides and atrazine on Pimephales promelas.
Wacksman, M1, Belden, J1, Lydy, M1, 1 Southern Illinois University, Carbondale, IL, USA
ABSTRACT- Organophosphate insecticides (OPs) are often used in agricultural and residential settings. Atrazine is also widely used in agriculture being the most heavily applied herbicide in the United States. These chemicals are often found in run-off water at elevated concentrations, causing exposure to non-target species. Past research has shown greater than additive toxicity when invertebrates were exposed to mixtures of atrazine and OPs. This study applied past research of mixture toxicity to vertebrate species, specifically the fathead minnow. Groups of known age fathead minnows, P. promelas, (1, 17 & 53 d post hatch) were exposed to two OPs, chlorpyrifos and diazinon, in binary mixtures with atrazine. These tests were performed using static renewal methods with the endpoint being the 96 h LC50. Temporal variations were seen in the organisms' response to the OPs in a laboratory setting with younger organisms being significantly more sensitive to the chemical mixtures.
Key words: atrazine, organophosphate, mixture toxicity, Pimephales promelas