T9 PM Pyrethroid Insecticides in Urban and Agricultural Environments
Tuesday, 15 November 2005: 1:50 PM - 5:30 PM in 339-340

(AMW-1117-745405) Pyrethroid pesticide distribution and toxicity in urban creeks.

Amweg, E¹, You, J², ¹ University of California, Berkeley, Berkeley, CA, USA² Southern Illinois University, Carbondale, IL, USA

ABSTRACT- Pyrethroid pesticides are replacing organophosphates for many urban applications, including structural pest control, landscape maintenance, and for residential home and garden use. Past monitoring of pesticides in urban-dominated creeks has focused on the water column because the relative water solubility of organophosphates. Pyrethroids are highly sediment-associated however, and sediment quality in urban creeks has received little attention. The present study intends to determine if pyrethroids are detectable in urban systems and if concentrations are high enough to cause associated aquatic toxicity. A total of 15 California creeks and 12 Tennessee creeks were tested for pesticide residues in the sediments, and aquatic toxicity was determined by acute toxicity tests using the amphipod, Hyalella azteca . In California, 13 of the 15 creeks tested were toxic on at least one sampling occasion, and sediment pyrethroid concentrations were sufficient to explain the observed toxicity in most cases. None of the Tennessee creeks were toxic, and pyrethroids were rarely detectable above 1 ng/g. Distributions of individual pyrethroids are presented and potential explanations for the regional differences are discussed.

Key words: pyrethroids, sediment quality, Hyalella azteca