TitleA test system to evaluate the susceptibility of Oregon, USA, native stream invertebrataes to triclopyr and carbaryl.
Publication TypeJournal Article
Year of Publication2001
AuthorsPeterson, JL, Jepson, P, Jenkins, JJ
JournalEnviron Toxicol Chem
Volume20
Issue10
Pagination2205-14
Date Published2001 Oct
ISSN0730-7268
KeywordsAnimals, Carbamates, Dose-Response Relationship, Drug, Glycolates, Herbicides, Insecticides, Invertebrates, Lethal Dose 50, Risk Assessment, Time Factors, Water Pollutants, Chemical
Abstract

The susceptibility of six indigenous macroinvertebrate species representative of U.S. Pacific Northwest streams (Ameletus sp., Brachycentrus americanus, Calineuria californica, Cinygma sp., Lepidostoma unicolor, Psychoglypha sp. early and late instar) to formulated triclopyr ester (herbicide) and carbaryl (insecticide) was determined using laboratory bioassays. Acute toxicity was expressed as the lethal concentration to 50% (LC50) and 1% (LC1) of the test population based on a 96-h exposure duration. Carbaryl was found to be 1,000 times more toxic than triclopyr for all the organisms tested. The LCI values (7.5, 28.8, 9.0, 3.0, 9.5, 14.8, 33.8 microg/L, respectively, for carbaryl and 1.8, 3.9, 4.0, 4.2, 29.0, 16.1 mg/L, respectively, for triclopyr) were used in the calculation of hazardous concentration to 5% of the stream macroinvertebrate community (HC5) based on the lower 95% confidence limit (HC5/95). The hazardous concentration (HC5/95) for triclopyr was 0.11 mg/L and for carbaryl ranged from 0.43 to 0.66 microg/L, respectively. Triclopyr and carbaryl symptomology were analyzed for two organisms, C. californica and Cinygma sp. Carbaryl symptomology included knockdown and moribund states with severity and time of appearance being a function of dose. In triclopyr poisoning, death occurred suddenly with little or no symptomology. Time to 50% mortality (LT50) values were consistently higher for C. californica than for Cinygma sp. exposed to both chemicals at similar concentrations.

Alternate JournalEnviron. Toxicol. Chem.
PubMed ID11596752