Dr. Sinclair was President of the National Council on Radiation Protection and Measurements from 1977-1991 and is now President Emeritus at NCRP. He is a biophysicist with publications in radiological physics, radiobiology and radiation protection. He was born in New Zealand and educated in New Zealand and England before coming to the USA in 1954. He has a Ph.D. in physics from the University of London and served on the Staff at the Royal Marsden Hospital, London 1947-1954. He was Chairman of the Department of Physics at the MD Anderson Hospital 1954-1960 and later Senior Biophysicist, (1960-1983), Division Director and Associate Laboratory Director at Argonne National Laboratory in Chicago. He is Emeritus Professor of Radiology at the University of Chicago. He is a member of the International Commission on Radiological protection and a former member of the International Commission on Radiation Units and Measurements. He serves on the U.S. Delegation to the United Nations Scientific Committee on the Effects of Atomic Radiation and is presently Chairman of the Board on Radiation Effects Research at the National Academy of Science. He continues to undertake research in radiation risk assessment on behalf of NCRP and others.