Even low dose radiation exposure causes cancer

Jun 29 2005

A new study says that workers in the nuclear industry who are exposed to chronic low doses of radiation have a slightly higher risk of developing cancer.

Dr Elisabeth Cardis, head of the radiation group at the International Agency for Research on Cancer (IARC) in Lyon, France, says the study shows that even low doses of radiation causes cancer.

The risk, she says 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.

Radiation protection standards, which limit occupational exposure to ionising radiation to 100 millisieverts (mSv) over five years and 1 mSv per year for the public, are based mainly on data from survivors who had been exposed to high doses of radiation over a very short time period.

Cardis says 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, but their findings, she says,may finally settle the issue, as the study shows that the current basis for radiation protection appears to be reasonable.

In the largest study of nuclear workers ever conducted, researchers from IARC studied 407,000 nuclear industry workers in 15 countries who had been exposed to low doses over an extended time span.

They estimated that cumulative exposure could lead to a 10 percent raised risk of death from all types of cancer and a 19 percent increase from leukaemia, excluding lymphocytic leukaemia.

The study results suggest that only a small proportion of cancer deaths in the study group were due to chronic, low-dose exposure.

The scientists estimated that 1-2 percent of deaths from cancers, except leukaemia, in the nuclear workers in the study may be due to radiation and these were mostly were in older employees who had worked in the industry many years ago.

Cardis says they would have had the highest doses in the 1940s and 1950s when the radiation protection standards were much less than they are today.

The study is published in the British Medical Journal.