Under new guidelines, Japanese children are allowed to be exposed to 20 times more radiation than was previously permissible.
The new regulation means children can now be exposed to as much radiation as a German nuclear worker.
The government argues the change is essential to keeping schools open in the Fukushima region.
According to Nobel Prize-winning group Physicians for Social Responsibility, the new limits mean exposed children now have a one-in-200 risk of getting cancer, compared with a one-in-500 risk for adults.
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