Toxicological Basis of the ADI—Present and Future Considerations

Abstract - The ADI (or any other risk assessment estimation) is based on the evaluation of the entire toxicological data available at the time it is derived. It is therefore liable to revision either when additional data become available, or when data interpretation changes with increasing scientific knowledge. Ideally, to estimate permissible acceptable human pesticide intake, changes in the ADI should be as infrequent as possible. At the present time, the ADIs for many pesticides are based on incomplete data and/or on data derived from studies performed utilizing protocols which are no longer accepted. The studies presently accepted for supporting the ADI will be listed, and briefly discussed. It is apparent that the studies presently accepted for estimating the ADI, are not and can never be ideal, as long as knowledge continues to evolve. However it is possible to attempt to predict changes in present requirements. Such potential changes as the use of “in utero” exposure in carcinogenicity studies, longer term neurotoxicity studies, the modification of requirement for measurement of certain clinical chemical studies, and basic changes in reproduction studies will be discussed as well as new areas of toxicology, related to behaviour and immunology. The conclusion of the paper will be that the ADI (or risk factor) is not immutable. Thus, utilization of the estimated figure should be approached with caution, since in many instances considerable toxicological knowledge of the basis of the derivation is essential to the correct use of the ADI as a baseline for comparison with possible human pesticide intake or exposure.