Curie, Becquerel, Roentgen, Sievert, Grey:
Recent news of a mercury contamination incident at a local school reminded me of several incidents where radioactive materials were circulating in communities unaware of the dangers.
The worst of these has to be the 1987 Brazilian cesium-137 contamination case in Goainia. A piece of medical equipment in an abandoned building was torn open by two men scavenging for scrap metal, and the 4000 Curie Cs-137 source was removed and opened. They marveled at the glow, and proceeded to extract, separate and distribute the material to people in their neighbourhood. People rubbed it on their bodies in order to sparkle. People carried it in their pockets for luck. Two hundred forty four people were later found to be contaminated, and over a dozen probably died from the exposure. (source)
Then again, some people know the details what they are doing, but are a little young to comprehend the wider implications, like David Hahn. David was a Michigan boy scout trying to earn an Atomic Energy merit badge by building a functioning breeder reactor with the americium, radium, and thorium from commonly available items. The shed he worked in and most of his backyard is now buried in Utah after his amazingly productive makeshift lab was declared a Superfund cleanup site. You might not completely understand what your children are up to, but always be sure you know roughly what they are doing, like building a nuclear pile whose radioactivity can be detected five houses away. (Ken Silverstein's article in Harper's Magazine.)
A third incident I remember hearing about is probably a myth, since I could not find any trace of it, even on RADSAFE, which is about as authoritative a source as I could find. As I remember it, some Federal facility (LANL?) purchased a set of lawn furniture for an outdoor cafeteria remodeling project, and when it arrived, it set off the radiation detectors designed to keep radioactive materials from going out the gate. The source was traced to some medical equipment that was mistakenly smelted in a batch of scrap metal, thereby contaminating a large amount of recycled metal. If the federal facility had not purchased this particular batch of furniture, it was unlikely that this contamination would have been found.
Even if the above is a myth, there is so much international commerce that recycling practices will probably provide future examples of importing hot items. In November 2000, the Carrefour supermarket chain was advised that a series of Chinese-manufactured watch bracelets was contaminated with cobalt-60, and they had to recall the product. This was only detected because an employee of the French Tricastin nuclear facility had purchased the watch, and set off detectors at the plant. (NRPB statement, the original OPRI (IRSN) statement seems to be inaccessible).
Similar incidents have occurred lately around the Iraqi nuclear research center at Al-Tuwaitha, where looters removed all kinds of containers full of radioactive materials. The contents (like yellowcake) were simply dumped, and the containers were used for foodstuffs. The impact of this widespread exposure to some fairly high levels of radiation will not be felt for some time, and of course much of the damage is psychological.
Now I'm starting to itch. Where's my Geiger counter? And why can't nuclear science sort out its units?
Added June 8, 2009: Radioactive Cheese Grater: http://is.gd/TonB