By Jane M. Orient, M.D.
One of my personal projects is to help distribute RadStickers to American firefighters and police officers so they will have them in the event of a real nuclear disaster, such as detonation of a terrorist (or North Korean) nuclear bomb. I have a RadSticker on my credit card, and also carry a credit-card sized SIRAD (self-indicating instant radiation alert dosimeter, see http://www.jplabs.com). In addition, I have a NukAlert, which is a dose-rate meter that chirps like a bird if it detects dose rates greater than 0.1 rad/hr (http://www.nukalert.com).
My SIRAD is showing a dose of between 2 and 5 rads because I usually forget to take it out of my carry-on luggage before it goes through the x-ray machine. It has made about 20 trips through there by now. It makes me wonder how much the TSA agent gets from standing by the machine all day. It is shielded, of course, but how effectively? I don’t see any of those lead aprons that x-ray technicians wear. If I worked for TSA, I’d have a SIRAD in my pocket. Agents used to be issued dosimeters.
The main purpose of RadStickers is to prevent panic. They are not very sensitive, so they are not going to pick up background radiation, or the excess radiation from a load of bananas or pottery. The lowest reading is 25 rads. An acute dose of less than 100 rads probably wouldn’t make you sick. A dose between 300 and 400 rads causes acute radiation sickness and a 50% chance of death. There’s a widespread belief that the teeniest dose might increase your risk of getting cancer in 20 years, say adding 1% to the 25% risk you have anyway, but there is also much evidence that low doses are actually protective.
For perspective, here are some numbers. At the gate of one Japanese plant during a fire, the dose-rate was temporarily as high as 11,000 microsieverts/hr, quickly dropping back to 600 microsieverts/hr. The level at the edge of the evacuation zone was 300 microsieverts/hr. In the older radiation-protection units, that’s from 1.1 rem/hr down to 0.03 rem/hr. The dose from one chest x-ray is about 0.01 rem and from a full-body spiral CT scan up to 10 rem. (In this context 1 rem is about the same as 1 rad.) If you stood at the gate of the plant for 10 hours at the highest dose-rate, you’d get as much radiation as from the total-body CT scan.
Irresponsible terror-mongers have been distributing material on the internet predicting an instantly lethal dose of 750 rads hitting western and intermountain North America within 10 days. This is preposterous.