25,000 millirems per year level was the federal occupational limit during World War II and until about 1950 for radiation workers and soldiers exposed to radiation. The occupational limit became 15,000 millirems per year around 1950. In 1957, the occupational limit was lowered to a maximum of 5,000 millirems per year.
Bethlehem Steel in South Buffalo, the Linde plant in Tonowanda, NY, and other small plants and disposal sites in Western New York, especially Niagara County. It seems nobody knew what they were working on. Many worked overtime for the extra pay, only to acquire cancer or other problems many years later. Most were dead before the truth came out and lawsuits were settled much later.
Clearly USA became 5x more aware of the hazards of millirems over that decade. Too bad for the Manhattan era USA persons killed by the industry.