Comparative toxicity based on similar asymptotic endpoints (journal version)
Results of the laboratory tests are used in assessing the environmental risk of exposure to industrial chemicals. The combined effects of dose-level exposure and time-duration exposure are tested in the laboratory, but only a single endpoint reflecting the dose-level exposure at the end of the test period is routinely reported and used. At times, this might be sufficient, or the data otherwise inappropriate for calculation of more than a single endpoint. Nevertheless, an approach that makes a more complete use of existing sufficient test information is needed. One method is presented in this paper, the focus of which is the evaluation of an LC50 endpoint at a calculated exposure time. This calculation determines a condition for the toxicity curve to become established along the time axis. The authors refer to this condition of the dose-response curve as an asymptotic state and the LC50 calculated from it as the asymptotic LC50. An analysis of 152 toxicity tests using fathead minnows show that the 96-hr LC50 is 25% more conservative than the asymptotic LC50. The calculation of LC50 under asymptotic conditions better enables comparing toxicities of different chemicals on the basis of comparable dose-level and time-duration exposures.
- Research Organization:
- Environmental Protection Agency, Corvallis, OR (USA). Environmental Research Lab.
- OSTI ID:
- 6408759
- Report Number(s):
- PB-89-145031/XAB; EPA-600/J-88/243
- Resource Relation:
- Other Information: Pub. in Archives of Environmental Contamination and Toxicology, Vol. 17, 273-280(1988)
- Country of Publication:
- United States
- Language:
- English
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