Uncertainties in the environmental risk assessment of metals

As life has evolved in the presence of metals, the assessment of the potent ial adverse effects of metals on ecosystems requires a different approach t han those presently used for man-made organic substances. This article prov ides a brief review of applications and limitations of current techniques a nd presents, based on recent research results, suggestions for improving th e scientific relevance and accuracy of environmental risk assessments of me tals. The importance of the following factors responsible for major uncerta inties in current environmental risk assessments of metals are discussed: f actors affecting metal bioavailability and toxicity, the potential importan ce of deficiency effects (for essential metals), and held extrapolation of laboratory toxicity data. Possible (regulatory) consequences of inaccuratel y assessing the natural background concentrations of metals and acclimatiza tion/adaptation potential of laboratory organisms and resident communities are illustrated using examples of recent research, hypothesis development, and a probabilistic environmental risk assessment.