Maxed out: How much radiation can we take?

[n2doc]

25 April 2010 by Valerie Jamieson

In September 1987, two men entered an abandoned medical clinic in Goiânia, Brazil, and dismantled what they thought was a piece of valuable equipment. Within a day, both were vomiting. Diarrhoea and dizziness struck next. Unbeknown to them, the "scrap" contained a highly radioactive source used to treat cancer patients.

Scrap dealer Devair Ferreira, who bought the source, was intrigued by the blue glow it emitted in the dark. He kept the mug-sized canister of powder in his dining room and invited friends and family around to marvel at it. They touched the powder and daubed it on their bodies like carnival glitter, taking fragments of the radioactive caesium chloride salt home. Within a month, Ferreira's wife, his 6-year-old niece and two of his employees had died from acute radiation syndrome. In total, 249 people were contaminated.

Radiation doses, measured in sieverts, are calculated by taking into account the type of radiation and the area of the body that has been irradiated. All of the fatalities received between 4.5 and 6 sieverts in a matter of days. That's a huge dose when you consider that each year we receive an average of 2.4 millisieverts from natural sources such as radon.

The threshold for an early death is around 2 sieverts, and death is highly likely at 6 sieverts, though Ferreira received 7 and survived. He died in 1994 as a consequence of alcoholic liver cirrhosis. No one knows for sure why Ferreira survived the radiation. The most likely explanation is that he spent more time out of the house than his wife. This gave the cells in his body time to repair some of the damage done.

http://www.newscientist.com/article/mg20627562.500-maxed-out-how-much-radiation-can-we-take.html