Biomedical Engineering Reference
In-Depth Information
Table 13.7
Lifetime Risk for Incidence and Mortality for All Solid
Cancers and for Leukemia from a Dose of 0.1 Gy to 100,000
Persons in a Population Similar to that of the U.S.
∗
All Solid Cancers
Leukemia
Male
Female
Male
Female
Excess cases
800
1,300
100
70
Number cases without dose
45,500
36,900
830
590
Excess deaths
410
610
70
50
Number deaths without dose
22,100
17,500
710
530
∗
Adapted from BEIR VII Report (see references, Section 13.15).
age yearly background exposure (100 mSv), statistical limitations make it difficult
to evaluate cancer risk in humans.” Thus, cancer risk at low doses can at present
only be estimated by extrapolation from human data at high doses, where excess
incidence is statistically detectable.
Probably the most reliable risk estimates for cancer due to low-LET radiation are
those for leukemia and for the thyroid and breast. The minimum latent period of
about 2 y for leukemia is shorter than that for solid cancers. Excess incidence of
leukemia peaked in the Japanese survivor population around 10 y post-exposure
and decreased markedly by about 25 y. These observations are consistent with
leukemia experience from other sources, such as patients treated for ankylosing
spondylitis and for carcinoma of the uterine cervix. Solid tumors induced by radia-
tion require considerably longer to develop than leukemia. Radiogenic cancers can
occur at many sites in the body. We mentioned bone cancers in the radium-dial
painters and lung cancers in the uranium miners. The BEIR VII Report provides
extensive, detailed information on a wide variety of radiogenic cancers.
The BEIR VII Committee undertook the task of developing models for estimat-
ing risks between exposure to low doses of low-LET radiation and adverse health
effects. They derived models for both cancer incidence and cancer mortality, allow-
ing for dependence on sex, age at exposure, and time since exposure. Estimates
are presented for all solid cancers, leukemia, and a number of site-specific cancers.
Special assumptions (e.g., a DDREF) were applied when estimates in lifetime risks
for the U.S. population were made from data in the Life Span Study. As an example,
Table 13.7 gives a summary from the BEIR VII Report for lifetime risks for all solid
cancers and for leukemia. The Committee considered a
linear-no-threshold
model
as the most reasonable for describing solid cancers and a
linear-quadratic
model
for leukemia (cf., Fig. 13.5). The first line in the table shows the excess number
of cancer cases for males and females that would be expected if a population of
100,000 persons, having an age distribution similar to that of the U.S., were to re-
ceive a dose of 0.1 Gy of low-LET radiation. The number of cases in the absence
of this exposure is shown in the next line. The third and fourth lines display the
corresponding information for cancer deaths.
