Development of a Realistic Screening Tool for Evaluating Potential Ecological Risks Associated With Land-Application of Pulp and Paper Mill Biosolids. W. R. Alsop, P. O. Gwinn, J. H. Samuelian, and S. Clough; AMEC Earth & Environmental and NCASI
In 1997, Meyn et al. published "Terrestrial Wildlife Risk Assessment for TCDD in Land-Applied Pulp and Paper Mill Sludge" (Environ. Toxicol. and Chem. 16(9): 1789-1801). This paper presented an innovative, yet conservative approach for performing a screening ecological Monte Carlo risk assessment. Unfortunately, as with many screening approaches, it presented an unrealistic consideration of "real world" wildlife risk estimates. Exposure estimates were based on non-contemporary chemistry and toxicology data. The compounding of conservative assumptions results in the conclusions being less relevant to potential wildlife exposures to dioxin in present-day land applied pulp and paper mill biosolids. For example, expected hazard quotients to shrews ranged from 300 to 600 while 90th percentile hazard quotients for shrews ranged from 600 to 1000, which is not supported by current empirical data. This paper identifies those model parameters and/or distributions used in the Meyn et al., article that are found to be based on insufficient or outdated information, or where distributions used to represent those data were incorrectly described in the model. Using the revised distributions, this paper develops a transparent Monte Carlo analysis approach that will provide a more realistic tool for screening ecological risks associated with the land-application of pulp and paper mill biosolids.
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