It remains unknown if the health problems are linked to the release of massive amounts of radioactive materials from Tepco's damaged plant. But Hida is concerned.
"I am worried because I received such calls much earlier than I expected," he says.
The amount of research into and public knowledge about internal exposure to radiation is still limited because the United States "concealed" information about the problem for a long time after it dropped the atomic bombs on Hiroshima and Nagasaki in 1945, Hida says.
A native of Hiroshima, he was serving as an army doctor there when he was exposed to radiation from the atomic bomb. He has since treated more than 6,000 survivors and worked as a director of the counseling center at the Japan Confederation of A- and H-Bomb Sufferers Organizations.