Biomarkers In Environmental Monitoring And Its Application In Chironomus Spp

Abstract

In many developed countries, the enforcement of specific regulations had a significant positive effect on the level of environmental pollution in the last decades, especially through a reduction in point source pollution (e.g. building of sewage treatment plants) and the ban of some persistent chemicals (e.g. DDT, toxaphene). However point source pollution is still a matter of concern in numerous countries and non-point source pollution by organic (e.g. pesticides, dioxins) and inorganic (e.g. heavy metals) compounds is still a matter of concern worldwide. The assessment of environmental quality implies that the biological effects of pollutants could be monitored using adapted tools. Ecotoxicology is a multidisciplinary science which focus on the adverse effects of toxicants at various levels of biological organization and which may provide such tools. Ecotoxicological researches have first been devoted to the study the effects of environmental contaminants at the population, community or ecosystem levels (Forbes and Forbes 1994). However, these traditional approaches are sometimes inefficient, especially to adequately assess the effects of chronic exposure of organisms to low levels of xenobiotics and to detect early biological responses. Therefore, there has been a shift in emphasis towards understanding the sublethal effects of long-term exposure to contaminants at the individual level where exposure can be adequately described and assessed (Newman and Jagoe 1996). It has been necessary to perform studies on individuals at the biochemical and molecular levels where toxicant-induced responses are initiated. The effects of toxicants usually begin through an interaction between toxicants and biomolecules (e.g. enzymes, receptors, DNA). Effects then cascade through the molecular, biochemical, subcellular, cellular, tissue, organ, individual, population, community and ecosystem levels of organization. Therefore, the understanding of the effects of toxicants at the molecular or biochemical levels may provide some insights into the cause of effects identified at higher levels (Newman and Unger 2003). The biomarker approach can be an extremely useful tool for this kind of investigation and it has been increasingly used for environmental hazard assessment during the last ten years (Delpedge and Fossi 1994, Fossi et al. 2000).