Professor Steve P. McGrath

Rothamsted Research, Harpenden, AL5 2JQ

At present, the EU Risk Assessment on Existing Substances is focussing on metals. This requires that metal-specific concepts be developed, because unlike organics, metals do not degrade in the environment and some of them are essential elements for life. Therefore, a number of differences arise compared with what has been done before for toxic xenobiotic compounds. Risk assessments for Cd, Zn, Cu, Ni, Cr(VI) and Pb in the environment are at various stages at present. These assessments divide the environment into the compartments water, sediment and soil (human health effects are dealt with separately).

This presentation will focus on the terrestrial risk assessment and on Cd and Zn in particular. Results of laboratory toxicity tests are the primary data used in the assessments and extrapolations are made to the environment. The Predicted No Effect Concentration is then derived, based on the added metal approach. On the other hand, a predicted Environmental Concentration is also derived and if PEC > PNEC decisions are made about the danger. Some of the factors that affect the risk will be discussed, including lab to field extrapolation, bioavailability, aging (or fixation) of metals and the use of NOECs based on short-term laboratory tests.

Implications of the RAES on the use of metallic substances and comparison with soil geochemistry will also be presented. Because most of the RAES are not completed yet it is difficult to be conclusive about the outcome, but the importance of using the correct approaches and obtaining good experimental data is clearly a key issue.

Reference: Council Regulation (EEC) 793/93 on the evaluation and control of the risks of existing substances. Brussels.

For further information on the above event, please contact Jane Lund, Events Manger, Tel 01224 395000, Email: j.lund@macaulay.ac.uk