Dr. Fina P. Kaloyanova, M.D., Ph.D., D.Sc. , is professor and head of the Department of Toxicology in the Research Institute of Hygiene and Occupational Health, Medical Academy, Sofia, Bulgaria., Dr. Kaloyanova graduated in 1951 to the Medical Faculty in Sofia. In 1961 she obtained her Ph.D. and in 1974 her D.Sc. in the field of pesticide toxicology. She began working as a researcher in 1951, a senior researcher in 1961, and a professor in 1969. From 1972 to 1984 she was the director of the Research Institute of Hygiene and Occupational Health., Dr. Kaloyanova was a president of the Bulgarian Society of Preventive Medicine and now is a member of the board of the National Association of Medical Research Societies. She was vice president of the International Association of Rural Medicine from 1972 to 1975, and a board member of the Permanent Commission and Internatinal Association for Occupational Health from 1972 to 1978. She was elected as a member of the International Academy of Environmental Safety., She has received several Distinguished Service Awards from the Medical Academy, Ministry of Public Health, Bulgarian Government., Dr. Kaloyanova has been a member of the expert panel on occupational health of the World Health Organization since 1972. She participated as a temporary advisor and consultant of more than 50 WHO meetings. She has presented many guest lectures at international and national courses in Egypt, Cuba, China,U.S.S.R, Algeria, Poland, Yugoslavia, and elsewhere. Dr. Kaloyanova has published over 250 research papers and books. Her current major research interests relate to pathogenesis of the pesticide intoxication and determination of the threshold level of the toxic action., Dr. Mostafa A. El Batawi, M.D., D.Sc. , is an adjunct professor at the University of Pittsburgh Graduate School of Public Health and a consultant to the World Health Organization, Geneva, Switzerland., Dr. El Batawi received his M.D. in 1951 from Cairo (Egypt) University Facu