June 28, 2005

Cancer risk linked to radiation exposure -study

By Patricia Reaney

LONDON (Reuters) - Nuclear industry workers exposed to
chronic low doses of radiation have a slightly higher risk of
developing cancer, scientists said on Wednesday.

"We have shown that even low doses of radiation cause
cancer," said Dr Elisabeth Cardis, head of the radiation group
at the International Agency for Research on Cancer (IARC) in
Lyon, France.

But she added 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.

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.

"There has been a controversy for decades about the use of
data on A-bomb survivors for setting standards for the
protection of the general public and radiation workers," Cardis

But the findings, which are reported in the British Medical
Journal, may settle the issue.

"Our study shows that the current basis for radiation
protection appears to be reasonable," Cardis added.

In the largest study of nuclear workers ever conducted,
researchers from IARC estimate that cumulative exposure could
lead to a 10 percent raised risk of death from all types of
cancer and a 19 percent increase from leukemia, excluding
lymphocytic leukemia.

The researchers studied 407,000 nuclear industry workers in
15 countries who had been exposed to low doses over an extended
time span.

The results suggest 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 leukemia, in the nuclear workers in the
study may be due to radiation.

But they added that most were in older employees who had
worked in the industry many years ago.

"Those who had the highest doses worked in the 1940s and
1950s when the radiation protection standards were much less
than they are today," Cardis said in an interview.
(HEALTH-CANCER-RADIATION, editing by Steve Addison, Reuters
Messaging: [email protected]))