Tokyo (CNN) After reactors at the Fukushima Daiichi nuclear plant suffered catastrophic meltdowns, thousands of workers were sent in to deal with the aftermath.

Now, more than four years later, Japan has confirmed the first case of cancer related to that dangerous work.

The country's health ministry said Monday a former Fukushima worker who was diagnosed with leukemia was entitled to workplace compensation.

The unnamed man in his 30s worked at the plant from October 2012 to December 2013, and was exposed to high levels of radiation, the ministry said.

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"This is a massive blow to the IAEA, which stated in September of this year that no discernible health effects due to the exposure to radiation released by the accident are to be expected," Greenpeace said.

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