Nuke-sector study sees rising cancer risk, 1 in 100 deaths, from prolonged low-dose radiation exposure


Prolonged exposure to even low doses of radiation increases the risk of cancer, according to a new study of workers in the nuclear sector in Britain, France and the United States.

The results, published Wednesday in the British Medical Journal, provides “direct evidence about cancer risks after protracted exposures to low-dose ionizing radiation,” said the International Agency for Research on Cancer (IARC), the cancer agency of the World Health Organization, which coordinated the study.

The findings demonstrate “a significant association between increasing radiation dose and risk of all solid cancers,” said the study’s co-author, IARC researcher Dr. Ausrele Kesminiene.

“No matter whether people are exposed to protracted low doses or to high and acute doses, the observed association between dose and solid cancer risk is similar per unit of radiation dose,” he added.

The International Nuclear Workers Study (INWORKS), a collaboration between international partners, evaluated the exposures of more than 300,000 nuclear workers in Britain, France and the United States between 1943 and 2005.

The results showed that the risk of death from solid cancers was “modest” but that 1 in every 100 cancer deaths could be attributed to workplace radiation exposure.

“The findings are important not only for the protection of workers in the nuclear industry but also for medical staff and the general population,” since the level of doses received by nuclear workers is comparable with that received by patients repeatedly exposed to CT scans or other radiology procedures, said IARC researcher Dr. Isabelle Thierry-Chef.

“This stresses the importance of striking a balance between the risks and the benefits of such medical imaging procedures,” she added.

The average age of workers in the study was 58 years.

  • Starviking

    An interesting study, but with some limitations. The editorial in the BMJ, entitled “Low risk, but not no risk” comments (emphases mine):

    Although exclusion of lung cancer—the cancer with strongest relative risk associated with smoking—had almost no effect, exclusion of a larger group of all cancer sites related to smoking (about 70% of all solid cancers) from analyses reduced the magnitude of the association, which also became non-significant. This suggests either heterogeneity of radiation risk by cancer site or some degree of confounding by smoking.

    The failure to take dose uncertainty into account is another weakness, especially because the uncertainties in some organ doses are substantial. Use of all solid cancers as an endpoint is also unfortunate, which includes highly radiogenic cancers (bladder, brain, breast, colon, liver, lung, and oesophagus) as well as cancers with much lower radiosensitivity (prostate, small intestine, uterus, and rectum). Correlation of this endpoint with a cumulative dose to the colon—which could adequately represent doses to deeper organs within the trunk but possibly not other body sites (brain, breast)—is another weakness.

    As such, the excess solid cancer risks associated with radiation in this cohort are modest: for the average worker, the lifetime risk of cancer death is likely to be increased by about 0.1% from a baseline risk of cancer death of about 25%. However, it is equally clear that the excess risks are unlikely to be zero.