Risks of radiation at low dose rates.

Cancer mortality has been studied in 1110 women who worked in the U.K. with paint containing radium from 1939 to 1961. Their body contents of radium were small, but they were also irradiated externally by gamma-rays to receive absorbed dose rates of 1-4 mGy per week. Those in the group who were under 30 years of age when they started work show a significantly increased risk of dying from breast cancer. If the excess were due solely to their radiation exposure, it would represent a risk of 20-500 deaths from breast cancer per 10(4) women exposed to 1 Gy, which is consistent with the value used by the International Commission on Radiological Pretection.

The toxicity of 90Sr, 226Ra and 239Pu.

Data now available on the risks of radiation-induced fatal cancer and hereditary disease and radionuclide metabolism suggest that limits on the rates of intake of 90Sr, 226Ra and 239Pu at work, presently recommended by the International Commission on Radiological Protection, might be in need of considerable revision one with another and with the limit for uniform exposure of the whole body.