At least 4,000 people died as a result of nuclear projects during the Cold War, and 36,500 became ill with radiation-related diseases, the Rocky Mountain News reported Friday.
The News said it collected the numbers by records from federal projects involving uranium, including the building and testing of bombs, and did not include people who had never filed claims or whose claims were rejected.
People who mined uranium, built bombs and who inhaled dust from bomb tests - whether they were workers or nearby residents - were included in the tally.
The nation built 70,000 atomic bombs, beginning in 1945.
Some of the uranium used in the bombs dropped on Japan came from Uravan, Colo.
About 15,000 workers were employed 15 miles west of Denver at Rocky Flats, making plutonium triggers for the bombs.
Of the 36,500 who became ill, about 15,000 were involved in the manufacture of bombs.
The radiation they were exposed to sometimes took years to affect them.
Some of them may have ultimately died as a result of their work, but were not listed among project deaths by the government.
Hundreds of thousands of people, including soldiers, were exposed to radiation from nuclear tests.
"In those days, we were training military personnel to fight a nuclear war. The Department of Defense had to know the effect on soldiers, sailors and airmen who moved within hours into a hot zone," said R.J. Ritter, who now runs the National Atomic Veterans Association and lobbies for aid to those contaminated troops.
"Nobody had a clue what would happen years later from inhaling those particles."
Although many of those exposed were not warned of the danger, lawsuits have revealed that government officials were aware of it.
"A lot could have been prevented if they had given the least bit of warning" said J. Turner, of www.downwinders.org.
The government first admitted the problem in the 1980s, but finding
records of those affected remains difficult.