At the Atomic Heritage Foundation, we receive many inquiries about the history of the Manhattan Project. One question we get asked a lot is, how many people died during the Manhattan Project?
Historian Alex Wellerstein has discovered a list of all the fatal accidents that occurred at Los Alamos in 1943 through September 1946. There were 24 deaths during this period. They include the criticality accidents that killed Harry Daghlian and Louis Slotin, but other deaths included a child who drowned in the pond and several construction, driving, and horse riding accidents.
The total number of fatalities at Hanford and Oak Ridge from 1943-1945 was 62; 54 were construction employees. 3,879 workers at the sites also suffered disabling injuries. (See page 78 of Manhattan District History, Book 1, Volume 11, Part 1, General Safety Program, Appendix B-3.) Wellerstein notes, "At Oak Ridge and Hanford, they claimed an exceptional occupational safety record - their injury rates were (they claimed) 62% below those of private industry." Many Manhattan Project veterans recalled the strict safety regulations enforced by DuPont at Hanford.