The determination of the hazards resulting from the accidental or deli berate contamination of terrestrial and aquatic environments is in most countries still lirnited to the detection and quantification of the suspected pollutants by chemical analyses. Such an approach is unfortunately hampered by the following constraints: the costs as weil as the technical difficulties of analyzing every individual chemical which may be present in the sampies, and the difficulty of assessing the hazards and risks of environmental contaminations from a set of chemical data. During the last decades the...