Use of Biomarkers to Evaluate Effects of Xenobiotic Compounds in the Biobio Basin (Central Chile)

The aim of the present study was to make a preliminary evaluation, by means of biomarkers, of the toxicological effects of xenobiotic compounds on the biota of the basm of the River Biobio in Chile. A biomarker is defined as " ... a xenobiotically-induced variation in cellular or biochenucal components or process, structures, or functions that is measurable in a biological system or samples"(NRC 1989). Such variations provide information on the amplitude of response of an orgamsm m relation to the magmtude of chenucal insult and on the relation between biological effects and environmental contamination. The study of biomarkers m biomdicator orgamsms, sampled in one or more areas suspected of pollution, and compared with those of organisms from a reference area, makes it possible to evaluate the potential danger to commumties (McCarthy et al. 1989. McCarthy & Shugart 1990, Fossi & Leonzio 1994). Such an approach is appropriate in situations of high hiunan unpact, as in the Biobio River m Central Chile. It provides an "integrated" response to overall exposure, in spatial and temporal terms, comprehensive of the various toxicological and pharmacological interactions of the pollutant mixture to which the bioindicator orgamsms are exposed. The biomarkers chosen to evaluate environmental quality in the Biobio basra were the nuxed function monooxygenases (MFO), indicators of chemical stress due to organochlormes, PAHs, dioxines and pentachlorophenols (Payne et al. 1987: Fossi and Leonzio 1994) and the esterases, mchcators of chenucal stress due to organophosphates, carbamates and neurotoxms (Thompson et al. 1988; Walker 1989).