Would You Care for Some Millisieverts With That?

When it comes to the Fukushima disaster, the worst may be over. Now, the thing we have to fear, one professor says, is fear itself.

With the restoration of power to the crippled reactors at Fukushima, and with the passage of time (allowing the nuclear materials to cool of their own accord), it may be that the worst is over. Let us hope so. Making sense of what has happened will take longer.

David Spiegelhalter, Professor of the Public Understanding of Risk at Cambridge, highlights our confusion over radiation risk in this excellent article for the BBC. The main thing we have to fear, he says, is fear itself.

It has been estimated that 17 million were exposed to significant radiation after Chernobyl and nearly 2,000 people have since developed thyroid cancer having consumed contaminated food and milk as children.

This is very serious, but nothing like the impact that had been expected, and a UN report identified psychological problems as the major consequence for health.

The perception of the extreme risk of radiation exposure is also somewhat contradicted by the experience of 87,000 survivors of Hiroshima and Nagasaki, who have been followed up for their whole lives.

By 1992, over 40,000 had died, but it has been estimated that only 690 of those deaths were due to the radiation. Again, the psychological effects were major.

Radiation does, however, feel acceptable when used in benign circumstances such as medical imaging. You can pay £800 ($1000) and get a whole-body CT scan as part of a medical check-up, but it can deliver you a dose equivalent to being 1.5 miles from the centre of the Hiroshima explosion.

Because more than 70 million CT scans are carried out each year, the US National Cancer Institute has estimated that 29,000 Americans will get cancer as a result of the CT scans they received in 2007 alone.

Meanwhile, in Taipei, a high-end restaurant is giving diners a geiger counter to scan their sashimi.