Journal article
How closely do acute lethal concentration estimates predict effects of toxicants on populations?
Integrated environmental assessment and management, Vol.1(2), pp.109-113
04/2005
Handle:
https://hdl.handle.net/2376/112468
PMID: 16639892
Abstract
Acute lethal dose/concentration estimates are the most widely used measure of toxicity and these data often are used in ecological risk assessment. However, the value of the lethal concentration (LC50) as a toxicological endpoint for use in ecological risk assessment recently has been criticized. A question that has been asked frequently is how accurate is the LC50 for prediction of longer-term effects of toxicants on populations of organisms? To answer this question, Daphnia pulex populations were exposed to nominal concentrations equal to the 48-h acute LC50 of 6 insecticides, Actara, Aphistar diazinon, pymetrozine, Neemix, and Spinosad; and 8 agricultural adjuvants, Bond, Kinetic, Plyac, R-11, Silwet, Sylgard 309, Water Maxx, and X-77; for 10 d. None of the D. pulex populations exposed to the acute LC50 of these insecticides were 50% lower than the control populations at the end of the study; exposure to diazinon resulted in populations that were higher than expected (91% of the control). Exposure to Actara and Aphistar resulted in populations that were < 1 and 29% of the control, respectively. Exposure to Fulfill, Neemix, and Spinosad resulted in extinction. Extinction occurred after exposure to all of the adjuvants, except Silwet L-77 where the population was 31% of the control. These results corroborate other studies that indicate that the LC50 is not a good predictor of effects on population growth. Although lethal concentration estimates have their place in toxicology, namely to compare intrinsic toxicity of chemicals among species or susceptibility of a species to different chemicals over short time periods, population growth and growth-rate studies are necessary to predict toxicant effects on populations.
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Details
- Title
- How closely do acute lethal concentration estimates predict effects of toxicants on populations?
- Creators
- John D Stark - Washington State University, Puyallup Research and Extension Center, Puyallup, Washington 98371, USA. starkj@wsu.edu
- Publication Details
- Integrated environmental assessment and management, Vol.1(2), pp.109-113
- Academic Unit
- Entomology, Department of
- Publisher
- United States
- Identifiers
- 99900547338801842
- Language
- English
- Resource Type
- Journal article