Toxicity risks associated with petrochemical wastes; based on resident cotton rats (Sigmodon hispidus)

Scope and method of study. Current research of our group is directed at studying the potential health effects of exposure to environmental contaminants associated with petrochemical wastes. The purpose of this study was (1) to evaluate the sensitivity of histopathological examination for detecting toxicity in cotton rats; (2) to assess toxicity risks associated with chronic exposure to fluoride by monitoring dental lesions in cotton rats; (3) to develop and validate a reproducible assay for evaluating responsiveness of bone marrow progenitor cells of the cotton rat to bone marrow toxicants; and (4) to evaluate the previous assay in our field study to investigate the impact of environmental contamination induced by petrochemical wastes. We monitored pathologic response of cotton rats in situ by seasonally collecting resident animals from replicated petrochemical waste sites and ecologically matched reference sites in Oklahoma over three years.;Findings and conclusions. Evaluation of environmental hazard of industrial waste sites using morphological and histopathological parameters of cotton rats were not sensitive enough to detect subtle toxicity induced by exposure to petrochemical wastes. Cotton rats inhabiting petrochemical waste sites contaminated with fluoride had substantial risks of developing dental fluorosis. We detected significant suppression of bone marrow granulocyte-macrophage progenitor cells in cotton rats exposed to petrochemical wastes. This result suggested that in vitro bone marrow progenitor culture could be served as one of the most sensitive indicators for study of ecotoxicity risks associated with environmental contaminants. The findings of our study will be useful in assessing risks to terrestrial ecosystem and in making predictions regarding human health risks.