Radiation exposure leukemia from

Stather JW, Dionian J, Brown J, et al. 1988. The risk of leukemia in sea scale from radiation exposure. Health Phys 55(2) 471-481. 

In the simplest of such uses, attribution of risk is performed after a cancer has already occurred in order to assign blame or legal liability. Obvious examples have come finom attempts to attribute risks of cancer to previous radiation exposure, but others have also come from previous chemical exposures, e.g., in the case of leukemia following exposure to benzene. 

Only in a few instances have the exposures been sufficiently marked to allow attribution, as in the case of a heavily exposed survivor of the A-bombings in Japan who subsequently developed leukemia. From the magnitude of the survivor s radiation exposme and fiwm epidemiological data on the incidence of leukemia in the population at the same exposure level, we might infer that the survivor s increase in risk corresponded to a 2 percent lifetime incidence, in contrast to the normal lifetime leukemia incidence of about 0.5 percent. The attribution would then be 2/2.5, or 80 percent, leaving 20 percent for background radiation and other causes. 

Cancer is the major effect of low radiation doses expected from exposure to radioactive contamination. Laboratory studies have shown that a-, /S-, and y-radiation can produce cancer in virtually every tissue type and organ in animals that have been studied (ATSDR, 2001). Cancers observed in humans after exposure to radioactive contamination or ionizing radiation include cancers of the lungs, female breast, bone, thyroid, and skin. Different kinds of cancers have different latency periods leukemia can appear within 2yr after exposure, while cancers of the breast, lungs, stomach, and thyroid have latency periods greater than 20 yr. Besides cancer, there is little evidence of other human health effects from low-level radiation exposure (ATSDR, 2001 Harley, 2001). 

Long-term health effects from exposure to low-to-moderate doses of radiation include cancer of the thyroid, prostate, kidney, liver, salivary glands, and lungs Hodgkin s disease leukemia and increased numbers of stillbirths and genetic defects. Concerns about potential long-term health effects often lead to anxiety and depression problems among those exposed to radiation. 

The current health risks associated with exposure to low-dose radiation are extrapolated from high-dose data taken from the Life Span Study of the Japanese atomic bomb survivors. Currently, a linear no threshold extrapolation is recommended. The numerous technical reports and scientific papers about the Japanese A-bomb survivors were widely interpreted as showing that the effects of occupational exposures to radiation would be too small to detect in epidemiological studies. However, questions about the reliability of the A-bomb results were presented by Stewart and Kneale [2]. Their Oxford Childhood Study observed that children whose in utero exposures were as little as 10 to 20 mSv had 40% more childhood leukemias than those who were not exposed. No similar effects are reported in the A-bomb data. Of course, the finding of no effect is not a compelling argument for or against a safe dose. 

If the exposure had been much smaller, the risk calculation would have been less direct and less certain. For purposes of risk reduction in public health, we may choose to err on the pessimistic side in risk estimations. For purposes of attribution, however, we want to make best estimates. Most of the numbers in Ikble 8.4 are overestimates of the risks. For radiation-induced leukemia, as described in Section 6.1.2, the best dose-incidence model might be lineai>quadratic and not linear. Thus, someone exposed to 50 mSv (5 rem) might be considered, on a linear extrapolation basis, to have a radiation related lifetime risk of cancer mortality of 10 (2 x 10 Sv 2 x 10 rem ), or a lifetime risk of mortality from leukemia of approximately 1.5 x 10 (0.3 x 10" Sv 0.3 X 10 rem ). The natural lifetime risk of mortality from leukemia other than chronic lymphocytic leukemia is approximately 56 x 10 . Therefore, the percent attribution to radiation according to the linear model would be ... 

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