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
E-Mail hopkinsw@vt.edu
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. p. 35-62. In Toxicology of Reptiles, edited by S. C. Gardner and E. Oberdörster. CRC Press. Hopkins, W. A. 2006. Use of tissue residues in reptile ecotoxicology: A call for integration and experimentalism. p. 35-62. In Toxicology of Reptiles, edited by S. C. Gardner and E. Oberdörster. CRC Press.
