Radiation risksWe still don’t really know the health hazards of a nuclear accident
Five years after the nuclear disaster in Fukushima and thirty years after the Chernobyl accident, scientists are still disagreeing about the impact on human health — such as how many people have got cancer as a result and how dangerous the exclusion zones currently are. The people of Fukushima, except those in the worst contaminated areas, will eventually be encouraged to return to their homes. In the absence of better understanding, scientific and political arguments about how safe the radiation levels are will continue. What is abundantly clear, though, is that we need to understand the comparative health effects of radiation versus relocation. Developing a new approach in our response to nuclear accidents and the decisions that are made in their immediate aftermath is vital so that we can avoid unnecessary panic and evacuation — something virtually all scientists agree on.
Five years after the nuclear disaster in Fukushima and thirty years after the Chernobyl accident, scientists are still disagreeing about the impact on human health — such as how many people have got cancer as a result and how dangerous the exclusion zones currently are.
In Fukushima, residents are forbidden to permanently return to their homes within the exclusion zone. And in Ukraine the city of Pripyat, 4 km from Chernobyl, still remains largely deserted. While some experts have recently said that the areas surrounding these accidents are not as dangerous as previously thought, others are concerned about the high levels of radiation remaining in plants and animals, particularly seafood.
It is true that large doses of radiation can be fatal. Marie Curie, who carried radium in her pockets, eventually died of cancer. But small doses of radiation are all around us, every day. They are measured in millisieverts (mSv). The average person in the United Kingdom receives a dose of 2.7 mSv per year (or 7.8 mSv per year if you happen to live on top of granite in Cornwall, which emits radon gas).
A transatlantic flight will give you a dose of 0.08 mSv from cosmic radiation. Even eating a humble banana will expose you to 0.001 mSv of radiation, from the tiny amount of radioactive potassium inside. But it is only really when you are exposed to annual radiation doses of more than 1,000 mSv that things start to get a bit hairy.
The type of radiation you are exposed to matters too. Some types only cause severe damage when ingested (lodged in the stomach or lungs). Other types can penetrate the body from outside, putting you at risk just walking by the source.
In the case of an accident, we have to take into account what sort of radiation is released – and how much – to take the right precautions. When radioactive gas from the Three Mile Island reactor in the United States was released after an accident in 1979, people were advised to stay indoors and to keep farm animals under cover. Later, pregnant women within a 20-mile radius of the reactor were recommended to evacuate. Within three weeks, 98 percent of the evacuees had returned. These were sensible precautions — after eighteen years of monitoring, no unusual health trends were reported. People only received an average dose of 0.08 mSv.
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