In a large study conducted by International Agency for Research on Cancer (IARC) in Lyon, France on nuclear workers has found that the workers who are exposed to chronic low doses of radiation have a slightly higher risk of developing cancer. This is the largest study ever conducted in 15 countries involving 407,000 nuclear industry workers. It was estimated that the chronic exposure could lead to a 10 percent raised risk of death from all types of cancer and a 19 percent increase from leukemia.
Dr Elisabeth Cardis, head of the radiation group at the International Agency for Research on Cancer (IARC) says that the risk appears to be similar to what scientists had estimated based on data from survivors of the atomic bombings in Hiroshima and Nagasaki, Japan in 1945.
The study was published in the British Medical Journal. The current radiation protection standards are based on data from survivors who had been exposed to high doses of radiation over a very short time period. At present .the generally accepted limit of occupational exposure to ionizing radiation is 100 millisieverts (mSv) over five years and 1 mSv per year for the public. Cardis in her study says that for decades there has been controversy about the use of data on A-bomb survivors for setting standards for the protection of the general public and radiation workers
On the hospital side no one is really sure if the X-rays done in the hospitals can cause an increased risks to cancer. A lifetime radiation levels below 100 millisieverts maybe safe. This dose is a little more than the dose from natural background levels and about 1,000 times the dose one receives from a single chest X-ray, However CT scan of the whole body is about 10 milliseiverts, hence this is area of some concern especially if someone has repeated scans.
This study helps to put to rest the "threshold" theory expounded by those who believe a totally "safe" level of radiation exists.