Geoökologisches Kolloquium WS 2002/03

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Prof. Paule Vasseur
Environmental Toxicology, University of Metz, France
Thursday, 23.01.2003 16:15 H6

Biomarkers in Ecotoxicology

The use of biomarkers is now a common approach in ecotoxicology. Biomarkers are biological parameters which measure behavior, biochemistry, physiology and genomic structure and expression, and are used as early signals of disturbances at the individual level. If disturbances originate from pollution, biomarkers then unambiguously express the bioavailability of pollutants, to which living species are exposed. The survey of biomarkers may be useful in environmental biomonitoring, especially for control of chemical contamination in order to prevent inherent toxic effects.

Biomarker responses traduce abnormalities in individuals, and are generally considered as indicators of unfavourable situations. Indeed the biomarker response may be a first signal of a cascade of changes which may lead to persistent lesions and toxicity at the individual level.
Yet, some biomarkers may also indicate that living species were better adaptable to eliminate the pollutants of concern, to neutralize or compensate their toxicity. In these cases, where biomarkers express adaptation and increased capacity to detoxication, the situation is not so unfavourable despite altered environmental conditions. Thus, beyond the fact that an environment may be disturbed, we also need to know whether toxic insults result in biological and physiological changes. This explains why several complementary biomarkers are generally used in order to have a complete picture of biological disturbances and their consequences in terms of toxicity. Moreover, it may be necessary to know if the toxicity observed at the individual level is detrimental at the population level. This confirms the interest of physiological biomarkers and the usefulness of associating populational bioindicators to biomarkers in environmental field studies.

We shall illustrate the use of biomarkers for environmental purposes with two examples of our present case studies related to biomarkers for environmental and human health.

Our first example relates to the use of biomarkers for environmental health. A two-year study in the Moselle river, using both biomarkers and populational indicators, was carried out in order to demonstrate the complementarity of ecotoxicological and ecological indices, and also to answer the following question : to which extent, the biomarker responses measured at the individual level in vertebrate (fish) and invertebrate (bivalves) species, were consistent with the ecological quality of the area studied?

The second example deals with biomarkers used for assessing sanitary risks due to the transfer of contaminants in the food chain, from invertebrates to humans. The aim of our study was to estimate potential effects on consumers, related to ingestion of food contaminated by polycyclic aromatic hydrocarbons (PAHs). Our purpose was to establish the threshold below which consumption of food was deemed devoid of effects in mammals, which justified the study of biomarkers of exposure to these pollutants.


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