### STP1403: A Probabilistic Analysis to Determine Ecological Risk Drivers

Johnston, RK

*Research scientist, Marine Environmental Support Office, Space and Naval Warfare Systems Center, San Diego, CA*

Munns, WR

*Branch chief and research biologist, U. S. Environmental Protection Agency, National Health and Environmental Effects Research Laboratory, Atlantic Ecology Division, Narragansett,*

Nacci, DE

*Branch chief and research biologist, U. S. Environmental Protection Agency, National Health and Environmental Effects Research Laboratory, Atlantic Ecology Division, Narragansett,*

Pages: 15 Published: Jan 2000

**Abstract**

A probabilistic analysis of exposure and effect data was used to identify chemicals most likely responsible for ecological risk. The mean and standard deviation of the natural log-transformed chemical data were used to estimate the probability of exposure for an area of concern and a reference area. Benchmarks of chemical effects were selected from criteria, standards, and toxicological thresholds in the literature and dose-response models developed for Pb were used to estimate the probability of an effect from Pb. Ecological risk, defined as the probability of exceeding a benchmark or causing an effect given the probability of exposure was calculated for the area of concern and reference area. The probability of an effect from Pb and probability of exceeding any combination of benchmarks were determined by Monte Carlo simulations. Chemicals that caused an incremental increase of risk ⩾ 0.05 above the reference area were identified as potential “risk drivers.”

**Keywords:**

ecological risk assessment, probabilistic, Monte Carlo, exposure, effect

**Paper ID:** STP10246S

**Committee/Subcommittee:** E47.01

**DOI:** 10.1520/STP10246S

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