SREL Reprint #2931

Use of tissue residues in reptile ecotoxicology: A call for integration and experimentalism

William A. Hopkins

Department of Fisheries and Wildlife Sciences, Virginia Polytechnic Institute and State University,
100 Cheatham Hall, Blacksburg, VA 24061

Introduction: "The classical approach to establish the hazard of toxic chemicals to wildlife is to determine the amount of a chemical present and then compare that value with those known to do harm in experimental animals." (D. Peakall, 1992).
Hazard and risk assessments in wildlife can be achieved by measuring contaminant levels in a variety of media, including water, sediment, soil and biological tissues. Tissue residues (i.e., tissue concentrations) have been advocated by some scientists because residues often provide greater insight into the exposure conditions experienced by an organism compared with concentrations of contaminants in surrounding environmental matrices. The power of using tissue residues lies in their integrative nature; they account for bioavailability resulting from physico-chemical characteristics of the site and chemical speciation of the contaminant, as well as ecologic and physiologic characteristics of organisms that may influence uptake and accumulation. However, accumulation of contaminants is not necessarily hazardous to organisms. Expression of effects will depend on concentrations accumulated, characteristics of the compound, the duration of chemical exposure, the sensitivity of the organism under study, and a host of other ecologic and physical variables that can influence responsiveness. Thus, quantifying tissue residues alone has limited utility in conservation and risk-oriented initiatives. For tissue residues to be maximally useful within a conservation framework, one should understand the following: (1) the tissue residue concentration relative to exposure concentration and exposure duration, and (2) the effect (or lack thereof) of these tissue residues on the health of the organism or closely related species.

SREL Reprint #2931

Hopkins, W. A. 2006. Use of tissue residues in reptile ecotoxicology: A call for integration and experimentalism. pp. 35-62 In S. C. Gardner and E. Oberdörster (Eds.). Toxicology of Reptiles. CRC Press.

This information was provided by the University of Georgia's Savannah River Ecology Laboratory (srel.uga.edu).