and dose rates . These developments have strengthened the epidemiologic data that are used to develop risk estimates . Box 1 lists some of the new epidemiologic information and approaches that have become available since BEIR V .
On average , assuming a sex and age distribution similar to that of the entire U . S . population , the BEIR VII lifetime risk model predicts that approximately one individual in 100 persons would be expected to develop cancer ( solid cancer or leukemia ) from a dose of 100 mSv while approximately 42 of the 100 individuals would be expected to develop solid cancer or leukemia from other causes ( see Figure 2 ). Lower doses would produce proportionally lower risks . For example , it is predicted that approximately one individual in 1000 would develop cancer from an exposure to 10 mSv . Table 1 shows BEIR VII ’ s best estimates of the lifetime attributable risk ( LAR ) of incidence and mortality for all solid cancers and for leukemia per 100,000 persons exposed to 100 mSv . The report also provides estimates for cancers of several specific sites .
Figure 2 . In a lifetime , approximately 42 ( solid circles ) of 100 people will be diagnosed with cancer2 from causes unrelated to radiation . The calculations in this report suggest approximately one cancer ( star ) in 100 people could result from a single exposure 100 mSv of low-LET radiation .
Risk Estimates at Very Low Doses
Excess cases ( including non-fatal cases ) from exposure to 100 mSv
At doses of 100 mSv or less , statistical limitations make it difficult to evaluate cancer risk in humans . A comprehensive review of available biological and biophysical data led the committee to conclude that the risk would continue in a linear fashion at lower doses without a threshold and that the smallest dose has the potential to cause a small increase in risk to humans . 3 This assumption is termed the “ linear-no-threshold ” ( LNT ) model .
There are two competing hypotheses to the linear no-threshold model . One is that low doses of radiation are more harmful than a linear , no-threshold model of effects would suggest . BEIR VII finds that the radiation health effects research , taken as a whole , does not support this hypothesis . The other hypothesis suggests that risks are smaller than predicted by the linear nothreshold model are nonexistent , or that low doses of radiation may even be beneficial . The report concludes that the preponderance of information indicates that there will be some risk , even at low doses , although the risk is small .
Health Effects Other than Cancer
Radiation exposure has been demonstrated to increase the risk of diseases other than cancer , particularly cardiovascular disease , in persons exposed to high therapeutic doses and also in A-bomb survivors exposed to more modest doses . However , there is no direct evidence of increased risk of non-cancer diseases at low doses , and data are inadequate to quantify this risk if it exists . Radiation exposure has also been shown to increase risks of some benign tumors , but data are inadequate to quantify this risk .
All Solid Cancer
Leukemia Males Females Males Females 800 ( 400 – 1600 ) 1300 ( 690 – 2500 ) 100 ( 30 – 300 ) 70 ( 20 – 250 ) Number of cases in the absence of exposure 45,500 36,900 830 590
Excess deaths from exposure to 100 mSv |
410 ( 200 – 830 ) |
610 ( 300 – 1200 ) |
70 ( 20 – 220 ) |
50 ( 10 – 190 ) |
Number of deaths in the absence of exposure |
22,100 |
17,500 |
710 |
530 |
Table 1 . The table shows the estimated number of cancer cases and deaths expected to result in 100,000 persons ( with an age distribution similar to that of the entire U . S . population ) exposed to 100 mSv . The estimates are accompanied by 95 % subjective confidence intervals shown in parentheses that reflect the most important uncertainty sources including statistical variation , uncertainty in adjusting risk for exposure at low doses and dose rates , and uncertainty in the method of transporting data from a Japanese to a U . S . population . For comparison , the number of expected cases and deaths in the absence of exposure is listed .
2Approximately 42 cancers per 100 individuals calculated from Table 12-4 in Chapter 12 of the BEIR VII report . 3 In special cases , such as in utero exposure , some evidence suggests excess cancers can be detected as low as 10 mSv .