Radiation risks: Raiders of the lost archive
http://www.nature.com/news/radiation-risks-raiders-of-the-lost-archive-1...
The town of Ozersk, deep in Russia's remote southern Urals, hides the relics of a massive secret experiment. From the early 1950s to the end of the cold war, nearly 250,000 animals were systematically irradiated. Some were blasted with α-, β- or γ-radiation. Others were fed radioactive particles. Some of the doses were high enough to kill the animals outright; others were so low that they seemed harmless. After the animals — mice, rats, dogs, pigs and a few monkeys — died, scientists dissected out their tissues to see what damage the radioactivity had wrought. They fixed thin slices of lung, heart, liver, brain and other organs in paraffin blocks, to be sliced and examined under the microscope. Some organs, they pickled in jars of formalin.
http://www.nature.com/news/radiation-risks-raiders-of-the-lost-archive-1...
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Biologists have generally assumed that the damage will be proportional to the dose, but in vitro studies have shown that cells can repair modest DNA damage caused by radiation — and that low-dose radiation might even protect the cell against future exposure.
“Maybe there is a threshold dose below which radiation is not harmful,” says Wolfgang Weiss, head of radiation protection and health at Germany's Federal Office for Radiation Protection in Munich. Epidemiological studies on people exposed to radiation through their jobs, nuclear accidents or medical procedures haven't shed much light on the matter. Some of the studies contained too few people to detect what could be a tiny increased incidence in disease; in others, it is unclear what dose the individuals received...