The funds herein requested are intended to make possible a third in a series of conferences on the Evaluation and Regulation of Safety of Chemicals, including drugs, food additives, industrial and agricultural chemicals (such as herbicides, pesticides, etc.). These conferences (the first one held in February 1982, the second in October 1983, both in the Greater Boston area) bring together scientists concerned with the mechanisms of the action of toxic substances and their evaluation, representatives of industrial organizations producing such chemicals, and regulators from various countries who are responsible in their own jurisdictions for the regulation of chemicals in the food supply, or as drugs and as contaminants in the environment of workplace and living space. The scope of subjects covered in the conferences is necessarily broad since an attempt is being made to cover most of the areas that present acute problems at the time of the conference or that constitute important methodological proggress capable of influencing the manner of regulation of chemicals. The effect of these conferences on the public health occurs at the time of the meetings through the interpersonal reactions between producers of chemicals and regulators and between the scientists of academia, the industrial laboratories and the regulatory agencies. This is carried into wider circles through the publication of the conference proceedings (Volume 1 appeared in August of 1983, Volume 2 is in press, and Volume 3 will be published within 6 months after the third conference). Because a large number of reprint requests was received from institutions in Europe following publication of the proceedings of the first conference, it was decided to hold the third conference at Zurich, Switzerland. This places the meeting within easy reach of most Europeans and, for the Eastern United States, is no farther away than the West Coast.