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LINKING EXPOSURE AND DOSIMETRY TO RISK FROM PHOTO-ACTIVATED TOXICITY OF PAHS
Citation:
Mount, D. R., S A. Diamond, R J. Erickson, M. F. Simcik, AND D. L. Swackhamer. LINKING EXPOSURE AND DOSIMETRY TO RISK FROM PHOTO-ACTIVATED TOXICITY OF PAHS. Presented at 22nd Annual SETAC Meeting, Baltimore, MD, November 11-15, 2001.
Description:
Hazard from photo-activation of PAHs has been well documented in aquatic organisms. Far less certain is the degree to which risk actually occurs in the field. One of the key difficulties in understanding this risk lies in quantifying exposure/dosimetry for both PAHs and UV radiation. This presentation focuses on the former, exploring issues relevant to estimating UV-enhanced potency of environmental PAH contamination. Experimental work has correlated photo-activated toxicity with accumulated tissue residues, but the estimation of PAH bioaccumulation in the field is confounded by several issues, including metabolic transformation/elimination and unusual sediment/water partitioning behaviors induced by soot, coal, and other matrices. Early life stages of fish show strong sensitivity to photo-activated toxicity in laboratory exposures and may not have the same metabolic transformation activity as do older fish. Moreover, if the dermal layer of larval fishes is a site of action for photoactivated PAH toxicity, which is reasonable to expect, whole-body accumulation of PAH may not be a prerequisite for risk. Additional uncertainties are introduced by the dozens of photoactivated structures that can be expected in environmental PAH mixtures, many of which are not quantified by typical analytical techniques for PAHs. Studies conducted using sediments from PAH contaminated sites suggest that as little as 5% of their potency is explained by commonly measured, unsubstituted PAHs. Even for the sites with extensive analytical chemistry, issues arise for estimating potency of structures that have not been directly tested.