In many ways, the key to Chiho Kaneko's Viewpoint [“Japan, one year later,” Voices, March 21] is in her remark, “If you believe as I do that any amount of radioactivity in one's body, especially in children's, is unnatural and therefore unacceptable, you would understand how serious this is.”
It's simply not the case that “radioactivity in the body” is unnatural. Each and every one of us is radioactive to a degree; indeed, one of the more significant causes of exposure is the radiation we receive from lying in a double bed next to our spouses/partners!
On that basis, it's simply not possible to say whether any given amount of radioactivity adds significantly to our exposures without seeing the actual numbers concerned.
A becquerel (Bq) measures how many radioactive disintegrations are happening per second, and hence tells us how much energy is being deposited in our cells from that decay. Each of us will have around 4,000 to 5,000 Bq of radioactive potassium in our bodies (assuming we're of around-average size).
It's also the case that the equipment available to detect radioactivity is fantastically sensitive. Equipment that can detect fractions of a becquerel is far from uncommon and, indeed, most of the figures I've seen for children exposed from Fukushima are of the order of 20-30 Bq/liter, which suggests whole body burdens of a few percent of the radio-potassium burden.
Nor are we, including children, especially sensitive to anything but very high doses of radiation.
Here in England, we've the county of Cornwall. Cornwall is mostly made of old, granitic rocks, and these rocks contain various radioisotopes. The decay of these isotopes leads to releases of radon gas.
The average background radiation in Cornwall is about 8-10 milliSieverts per year. That in London and the Home Counties is perhaps one-quarter of that. There are “hot spots” in Cornwall ranging up to 5 to 10 times the average for the area; any of you who've visited Dartmoor have possibly exposed yourself to some of the highest of these!
And yet, despite that huge differential, the rates for cancer and other rates of diseases with known links to radiation in Cornwall are certainly no higher, and arguably significantly lower, than they are for the rest of the U.K.
The big thing that this article points to is the psychological damage that's being caused by excessive hyping of radiation-related fears. And I'm afraid this article is yet another example of that!