Karel Valter (Ph.D 1990) is a consultant in chemistry and toxicology of drugs of abuse. Previously, he was a Research Chemist at Saute, Inc. (a subsidiary of Hofmann La Roche, Inc.) and Sapos, Inc. in GenevaPhilippe Arrizabalaga (Dr.Sc. 1984) is director of Ecotox and head of the section of general toxicology. He is professor of French universities and teaches courses of environmental impact assessment at the University of Geneva.