Simeon T. Cantril (1908-1959) was an American physician. He was born on February 17, 1908 in Hyrum, Utah. He was a graduate of Harvard Medical School. In 1938 he became the director of Swedish Hospital’s Tumor Institute. At Swedish Hospital, Cantril worked with Herbert Parker, with whom he worked throughout the Manhattan Project.
Cantril was recruited as a medical advisor for the Manhattan Project. Cantril was working at the University of Chicago when Chicago Pile-1 went critical. He then served as medical director at Oak Ridge.
Cantril later was the assistant medical director at Hanford. At Hanford, Cantril oversaw health physics research and developments in radiation monitoring. He and his staff also studied the effects of radioactive material on domesticated animals and vegetation.
Cantril died on September 10, 1959 in Orcas, Washington.