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SENSITIVITY ANALYSIS OF THE APPLICATION OF CHEMICAL EXPOSURE CRITERIA FOR COMPARING SITES AND WATERSHEDS
Citation:
Fulk, F A. AND S M. Cormier. SENSITIVITY ANALYSIS OF THE APPLICATION OF CHEMICAL EXPOSURE CRITERIA FOR COMPARING SITES AND WATERSHEDS. Presented at Society of Environmental Toxicology and Chemistry, Philadelphia, PA, November 12-14, 1999.
Description:
A methodology was developed for deriving quantitative exposure criteria useful for comparing a site or watershed to a reference condition. The prototype method used indicators of exposures to oil contamination and combustion by-products, naphthalene and benzo(a)pyrene metabolites, sampled from white suckers and common carp in the Eastern Cornbelt Plains Ecoregion of Ohio. Sites were selected by two sampling schemes. First through second order stream sites were selected by an intensified probability-based sampling design developed by the Environmental Monitoring and Assessment Program (EMAP). For larger streams, reference sites were selected by Ohio EPA ecologists. Numerical exposure criteria were determined by an empirical approach, the 95th percentile derived from ranked data. Binomial probabilities based on the number of fish exceeding the exposure criteria at a site and the number of fish sampled at a site were used to determine contamination. The percentile selected to represent the exposure criteria, i.e., 90th, 95th, 99th and the level of significance in determining contamination at a site, i.e., 1% vs 5%, may impact the final assessment. An analysis of the sensitivity of the final assessment to the selection of percentile and level of significance was conducted. Correlation of the contaminated sites with NPDES discharges and levels of contaminants in the water and sediment were used to confirm the presence of contamination at the designated sites.