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Abstract-A critical evaluation of literature on the behavior, physiology, and ecology of common estuarine organisms was conducted in an attempt to develop probabilistic distributions for those variables that influence the uptake of xenobiotic chemicals from sediments, water, and food sources. The ranges, central tendencies, and distributions of several key parameter values were identified for dominant organisms from various trophic levels, including the polychaete Nereis virens, mummichog (Fundulus heteroclitus), blue crab (Callinectes sapidus), and striped bass (Morone saxatilis). The exposure factors of interest included ingestion rate for various food sources, growth rate, respiration rate, excretion rate, body weight, wet/dry weight ratio, lipid content, chemical assimilation efficiency, and food assimilation efficiency. These exposure factors are critical to the execution of mechanistic food web models, which, when properly calibrated, can be used to estimate tissue concentrations of nonionic chemicals in aquatic organisms based on knowledge of the bioenergetics and feeding interactions within a food web and the sediment and water concentrations of chemicals. In this article we describe the use of distributions for various exposure factors in the context of a mechanistic bioaccumulation model that is amenable to probabilistic analyses for multiple organisms within a food web. A case study is provided which compares the estimated versus measured concentrations of five polychlorinated biphenyl (PCB) congeners in a representative food web from the tidal portion of the Passaic River, New Jersey, USA. The results suggest that the model is accurate within an order of magnitude or less in estimating the bioaccumulation of PCBs in this food web without calibration. The results of a model sensitivity analysis suggest that the input parameters which most influence the output of the model are both chemical and organism specific.

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A Creel/Angler Survey (CAS) was conducted to provide site-specific information on recreational fishing in the lower six miles of the Passaic River (Study Area). Information collected during the CAS will be used to develop site-specific exposure factors, including fish consumption rates, for use in the human health risk assessment required by an Administrative Order on Consent as part of the Remedial Investigation/Feasibility Study for the Study Area. An expert panel was convened to provide an independent opinion regarding the need for, design of, and implementation of the CAS. The expert panel was charged with evaluating whether the conduct of a CAS is necessary to support an accurate risk assessment for the Study Area and whether the proposed CAS is sufficient to characterize local fish consumption behavior for risk assessment purposes. The expert panel agreed that a CAS is necessary and concluded that the proposed CAS, with specific modifications to the study design and data analysis, would provide the information necessary to estimate site-specific fish consumption rates. Revision of the CAS to accommodate the expert panel recommendations enhanced the quality of the data collected and ensured that the data will support the assessment of human health risks from consumption of fish from the Study Area.