Should Maine's Rivers Have Fish Advisories for Dioxin? Using an Integrated Microexposure Event and Toxicokinetic Model to Evaluate This Question. R. E. Keenan, J. D. Avantaggio, and P. S. Price, ChemRisk, A Division of McLaren/Hart, Stroudwater Crossing, 1685 Congress Street, Portland, ME 04102 Portland, ME 04102
The presence of polychlorinated dibenzo-p-dioxin (PCDD) and dibenzofuran (PCDF) congeners in fish downstream of pulp and paper mills has prompted some regulatory agencies to issue fish consumption advisories for a number of rivers and streams throughout the United States. In many cases, the basis for these advisories is a screening-level deterministic risk calculation. Increasingly, risk managers are interested in distributions of possible values rather than a single point estimate of potential risk. We developed the Microexposure Event analysis as a refined method of probabilistic exposure assessment that incorporates a number of demographic and temporal changes in the various exposure parameters to properly consider variation in fish concentrations, cooking practices, and fish species. In this paper, estimates of the high end exposed (HEE) angler are developed using the Microexposure Event model and the results are expressed as a distribution of dose rates. In addition, we linked the Microexposure model to a toxicokinetic model, the methodology of which is described in a companion paper. We estimated the hypothetical distribution of PCDD and PCDF concentrations in the blood of anglers who potentially consume freshwater fish downstream of pulp and paper mills in Maine. Results based on the two dosimetry methods provide insight as to whether Maine’s fish advisories are still needed.