The Black Swan Lands in Japan – Part 2 – Biological effects of radiation

The leakage of radiation from nuclear power plants in Japan has prompted attempts to minimise the dangers of radiation. These efforts are, at best, misguided and at worst, intended to mislead.

One of the errors that I have frequently seen in the media is the confusion between acute and long term effects of radiation. “Radiation sickness” is an acute illness that requires high levels of radiation to manifest itself. However, long term effects of radiation such as cancer and genetic mutations can occur at relatively low levels of radiation. So, just because people are not dropping dead of radiation sickness does *not* mean that no ill effects are occuring.

Radiation can damage DNA in cells. During the repair process, a mistake may be made in reconstituting it. This can result in cancer that may not manifest itself for many years. If radiation damages germ cells (sperm or eggs) the children of the person exposed may have genetic mutations. Fetuses are also highly susceptible to radiation damage at certain stages of development. Exposure to radiation in the womb can result in many birth defects, including mental retardation, and predispose the child to cancer later in life.

Some pundits and public officials have suggested that low levels of radiation are like getting some extra X-rays. They should know that X-rays are considered carcinogens. Although the risk from a single X-ray is low, getting a lot of unnecessary X-rays is not a good idea. When large numbers of people are exposed to low, but above background, radiation, the odds that some of them will get cancer goes up.

Some have argued that background radiation can be relatively high in some areas and that therefore there is no risk to low levels of radiation. Those people should know that people exposed to relatively high “background” radiation are at increased risk of cancer. That is why homes with high levels of naturally occuring radon in their basements are urged to mitigate it.

Some pundits who apparently received good educations in the physical sciences have revealed a striking ignorance of biological processes. They appear to only be aware of the effects of external radiation. In fact, radiation can also be ingested in many forms. Fallout that may be at relatively low levels on the grass can be concentrated in the milk of cows who must eat large amounts of grass every day. Children who drink this milk will receive much more concentrated radiation than would be expected based on environmental sampling.

Low levels of radiation can cause long term health effects. They are hard to study because they involve stochastic processes (DNA damage and repair), variability in susceptibility (based on individual genetics) and a long lag time before the health effects are seen. However, there is substantial evidence that, on a population basis, even low levels of radiation can have health effects. Pretending they don’t exist won’t make them go away.

References

Radiation Protection – Health Effects
EPA

Radiation and Pregnancy: A Fact Sheet for the Public
CDC

Radioactive I-131 from Fallout
National Cancer Institute

Radon and Cancer: Questions and Answers
National Cancer Institute

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