CHROMOSOMAL ABERRATIONS IN RESIDENT SMALL MAMMALS AT A PETROCHEMICAL WASTE DUMP SITE: A NATURAL MODEL FOR ANALYSIS OF ENVIRONMENTAL MUTAGENESIS (DAMAGE, POLLUTANT, POLLUTION, MUTATION)

Small mammals of two species (Peromyscus leucopus and Sigmodon hispidus) were trapped at a locality polluted with a complex mixture of petrochemical waste products, heavy metals, and PCB's, and from two matched, uncontaminated localities. Three cytogenetic techniques were employed to evaluate the use of these resident small mammals as indicators of environmental mutagenesis. Each technique also was assessed for its power of resolution in characterizing the action of environmental mutagens.;Examination of flow DNA histograms of Peromyscus from the polluted site revealed broadened and flattened G(,1) peaks and increases in CVs (coefficients of variation) for DNA content. CVs in animals from the polluted site consistently fell outside confidence limits set around values from animals collected at the uncontaminated site. These patterns are characteristically seen in laboratory animals challenged with powerful clastogens which suggests that individuals at the polluted site may be experiencing similar clastogenic events.;G-band karyological analysis did not reveal significant differences in aberrancy between the polluted site and the control sites but did indicate that unique responses occur in individual chromosomes. Two chromosomes (5, 21) were found to be exceptionally susceptible to rearrangement. Several classes of aberrations not detectable in standard karyotypes also were observed in G-band karyotypes.;This study demonstrates that small mammals are a feasible test model for evaluating environmental mutagenesis. Evaluation of different cytogenetic techniques suggests that a battery of several assays will provide the most accurate characterization of the action of environmental mutagenesis.;Standard karyological analysis of flow cytometric analysis clearly indicated significant differences in chromosomal aberrancy between animals collected at the polluted site and the uncontaminated sites. Standard karyology showed increases in lesions per cell and aberrant cells per individual for both species at the polluted site. Peromyscus apparently was more susceptible to chromosomal aberration than Sigmodon at both the polluted site and one control site.