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Radiation-Induced Cancer Risks
Who studies cancer risks
Risk estimates for radiation-induced cancer were first evaluated by scientific
committees starting in the 1950s. The following bodies now study cancer
risks:
These commissions and committees examine groups such as populations exposed
to medical sources of radiation, to Japanese atomic bomb survivors, populations
exposed to releases from Chernobyl, and to uranium miners, for instance.
What They Conclude
The BEIR Committee has issued several recent reports, including the BEIR
IV and BEIR
V reports. These reports state that:
- "It is fair to say that we have more scientific evidence on the
hazards of ionizing radiation than on most, if not all, other environmental
agents that affect the general public." (NAS,
1980, p.11)
- "It is not yet possible to estimate precisely the risk of cancer
induction by low-dose radiation, because the degree of risk is so low
that it cannot be observed directly and there is great uncertainty as
to the dose-response function most appropriate for extrapolating in
the low-dose region." (Ibid, p. 138)
The Linear No-Threshold Model
These bodies conclude that, until further studies clarify the risk
of cancer induction at low doses, it is prudent and conservative to
use the linear no-threshold (LNT) model to
estimate cancer risks.
Based on the known risk of cancer induction at high doses, the LNT
model linearly extrapolates risks at low doses and assumes there is
no threshold for cancer induction. Because we cannot prove there is
no risk at very low doses, we conservatively assume that any amount
of radiation, no matter how small, poses a cancer risk.
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