Calculating LOAEL/NOAEL uncertainty factors for wildlife species in ecological risk assessments
- EA Engineering, Science, and Technology, Inc., Hunt Valley, MD (United States)
Terrestrial ecological risk assessments frequently require derivation of NOAELs or toxicity reference values (TRVS) against which to compare exposure estimates. However, much of the available information from the literature is LOAELS, not NOAELS. Lacking specific guidance, arbitrary factors of ten are sometimes employed for extrapolating NOAELs from LOAELs. In this study, the scientific literature was searched to obtain chronic and subchronic studies reporting NOAEL and LOAEL data for wildlife and laboratory species. Results to date indicate a mean conversion factor of 4.0 ({+-} 2.61 S.D.), with a minimum of 1. 6 and a maximum of 10 for 106 studies across several classes of compounds (I.e., metals, pesticides, volatiles, etc.). These data suggest that an arbitrary factor of 10 conversion factor is unnecessarily restrictive for extrapolating NOAELs from LOAELs and that a factor of 4--5 would be more realistic for deriving toxicity reference values for wildlife species. Applying less arbitrary and more realistic conversion factors in ecological risk assessments will allow for a more accurate estimate of NOAEL values for assessing risk to wildlife populations.
- OSTI ID:
- 218411
- Report Number(s):
- CONF-9511137--; ISBN 1-880611-03-1
- Country of Publication:
- United States
- Language:
- English
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