Approaches for developing probability distribution functions for acceptable toxicity reference values in risk management
Conference
·
OSTI ID:212089
- Triton Environmental Consultants Ltd., Richmond, British Columbia (Canada)
- Golder Associates, Burnaby, British Columbia (Canada)
- Bell Pole Co. Ltd., Lumby, British Columbia (Canada)
- EVS Consultants, North Vancouver, British Columbia (Canada)
- L.S. McCarty Scientific Research and Consulting, Oakville, Ontario (Canada)
Ecological risk assessment (ERA), rather than a criteria-based approach, was selected for determination of a site-specific remedial objective for pentachlorophenol (PCP) in soil at a decommissioned pole treating facility bordered by a salmonid bearing stream. A stochastic approach was adopted through the development of probability distribution functions (PDFs) to quantify uncertainty and accurately represent each variable. This also avoids the use of arbitrary safety factors thus minimizing the tendency towards excessive conservatism and retains more information about the systems under investigation. In defining the approach the authors conducted a workshop with practicing risk evaluators to debate and derive scientifically defensible approaches and concepts. Rather than using LOEL and NOEL data, the group agreed to employ the EC{sub x} method where EC{sub x} values are adopted as independent measures of effects endpoints of magnitude x%. Measurement endpoints included: growth (reductions within limits of normal variation), fecundity ({+-} 2 standard deviations), fish population distribution and abundance (within natural variability) as well as tissue concentrations (tainting levels, critical body residues). The procedures and rationale adopted by the group for determining appropriate endpoints, identifying aid screening toxicity data, setting the level of ``x`` in EC{sub x}, statistical methods used to calculate ``x``, use and selection of site specific, regional and other relevant fish population data as well as application and development of appropriate population models to calculate ecological risk in the long term are discussed. The results of this work are considered a significant forward step in the use of ERA in B.C.
- OSTI ID:
- 212089
- Report Number(s):
- CONF-9511137--; ISBN 1-880611-03-1
- Country of Publication:
- United States
- Language:
- English
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