Chapter 7 - Effect of Radiation on Human Health

The Issue

What risk does radiation pose to human health?

In this chapter the issue is considered under the following headings:

Factual Summary

Readers, in forming their own judgements on subsequent issues, may find useful the following factual summary derived from this chapter:

At sufficiently high doses, radiation can cause cancer, genetic defects, radiation sickness and even death.
At very much lower doses, within the limits allowed by the CNSC, there are no observations of these effects.
Nevertheless, as a prudent measure in regulating the nuclear industry, the CNSC assumes that any amount of radiation can cause cancer and genetic defects, according to the linear non-threshold hypothesis (LNTH).
On average, Canadians are exposed to 2 mSv of radiation each year, with variation across Canada up to more than twice this amount.
The CNSC has set an absolute limit of an additional 1 mSv per year as the dose to which members of the public may be exposed from nuclear-energy facilities; with the requirement that doses should be reduced below the limit as low as reasonably achievable, economic and social factors being considered.
According to the LNTH, and ICRP recommendations endorsed by the CNSC, 20,000 mSv of radiation would result in one cancer death, regardless of how the doses are distributed in the population concerned.
Critics claim that this underestimates the risk and that 5,000 mSv would result in one cancer death: some health-science professionals claim that the ICRP recommendations overestimate the risk and that there is a threshold, around the natural ambient level of 1 mSv per year, below which radiation causes no harm and could even be beneficial.

Go to Contents of Book