Ionizing radiation cancer risk

Archer, V.J., Oncology Overview, Selected Abstracts on Risk of Cancer from Exposure to Low Level Ionizing Radiation, PB84-922906, International Cancer Research Data Bank Program, National Cancer Institute, U.S. Department of Health and Human Services, Salt Lake City, Utah, (August 1984) ... 

The existing evidence does not exclude the existence of a threshold for some (perhaps even aU) forms of cancer, but the available epidemiological and laboratory data do not favor such a possibility. Hence, the interpolation models used by national and international experts for estimating the carcinogenic risks of low-level ionizing radiation are generally based on the assumption of a non-threshold dose-incidence relationship (ICRP, 1977 UNSCEAR, 1977 NAS/NRC, 1980 NCRP, 1980 Sinclair, 1981 Rail eta/., 1985). 

The models developed by the BEIR Committee (NAS/NRC, 1980) for assessing the risks of low-level ionizing radiation include consideration of differences in the duration of the latent period for different types of cancer and ages at irradiation, in accordance with the available epidemiological data. Salient features of the models are illustrated in Figure 8.6. Models for assessing the carcinogenic risks of chemicals... 

Land, C.E., Boice, J.D., Jr., Shore, R.E., Norman, J.E., and Tokunaga. M. (1980). Breast cancer risk from low-dose exposures to ionizing radiation Results of parallel analysis of three exposed populations of women, J. Natl. Cancer Inst. 65, 353. 

IARC (2000). International Agency for Research on Cancer. Ionizing Radiation, Part 1 X- and Gamma (y)-Radiation, and Neutrons, IARC Monographs on the Evaluation of Carcinogenic Risks to Humans, Vol. 75 (International Agency for Research on Cancer, Lyon, France). 

Prenatal diagnostic X-irradiation has also been linked to increased risk of leukaemia in offspring, as has therapeutic, high-dose, ionizing radiation in childhood for other cancers and for various non-neoplastic conditions (Ron et al., 1988a Chow et al., 1996). 

Ionizing radiation is a known environmental cause of female breast cancer. Breast cancer risk is significantly elevated in female survivors of the atomic bombings at Hiroshima and Nagasaki, but varies significantly depending on age at the time of radiation exposure. Relative risk at estimated exposure levels of 1 Sv was approximately 3-4 for women exposed before 10 years of age or between 10 and 20 years of age, but decreased to approximately 2 in women irradiated between 20 and 40 years of age and decreased even further in women exposed after 40 years of age (Boice et al., 1996). 

Radiation is feared because its delivery cannot be seen, and is often not measured, because it is only in retrospect that one realizes that radiation exposure has occurred. We accept the concept of linear, nonthreshold cancer induction from ionizing radiation (Harley, 2001, 2008) this allows calculation of cancer risk regardless of how small (or large) the dose may be. Calculating very low risks leads to calculating a risk that one would consider acceptably low, that is a risk below the ability to detect a response (Harley, 2001). 

On the basis of available evidence, the Committee on the Biological Effects of Ionizing Radiations (called BEIR V Committee) has recommended use of a lifetime excess risk (i.e., normal risk has been subtracted) of 0.08 per 100 rad for death from y-ray- or X-ray-induced cancer. This risk applies to the average person in the United States population (all ages considered) exposed to doses up to 10 rad, when... 

---