A scientist in Japan has been assessing the scope of the radiation problem in the wake of the nuclear disaster at the Fukushima Daiichi plant 5 years ago.
Ryugo Hayano, an expert in nuclear physics, has been working with high school students from Japan and overseas to analyze if there is any radioactive materials in local food.
"We have confirmed that the peach that we enjoyed today didn't contain cesium, detectable level of cesium," says Hayano, who is a professor at the University of Tokyo.
The government has been working to reduce radiation exposure in Fukushima but people are still concerned. Hayano has been trying to check the level of internal exposure to radiation there. Internal exposure occurs when people ingest radioactive materials, which can cause cancer or other diseases.
Knowing the Japanese government hasn't done much about internal exposure, he voluntarily started checking for it. Over the past 5 years, he has examined about 50,000 people.
Two years after the accident, Kuniko Usui, a resident of Fukushima, brought her 2-year-old daughter to Hayano. After the accident, Usui was worried about her daughter's health. Hayano found no signs of internal exposure.
"We were just terribly afraid. Although I imagined the worst, I was able to understand what was happening thanks to Hayano's prompt action," Usui says. "I was so relieved to find nothing was wrong. I was so happy, I was almost crying."
Hayano knew there were no devices that could measure radiation in newborn babies so he developed one himself. He tested more than 5,000 children.
"We found nobody who had detectable level of radiocesium," Hayano says.
He also wants to know more about radioactive iodine, which can cause thyroid cancer, especially in children.
Hayano thinks it's important to discuss these matters with local youth. He brought in a Spanish expert, who investigated the correlation between the Chernobyl accident and thyroid cancer, to speak with students.
They asked her if there is any similarity between Chernobyl and Fukushima.
"Right now you can't say anything about effects in Fukushima that you can say with screening," says Elizabeth Cardis, a professor at the Centre of Research in Environmental Epidemiology.
"Maybe in the future, screening continues and if the rates go up, then maybe you can say there is an effect of radiation."
Hayano thinks his research alone isn't the final answer to solve multiple issues in the future for people in Fukushima. He says it's important to keep monitoring everyone's health and to share the information with people there.
"In these five years, not just our data but other data as well have shown that the radiation risk to people, both external and internal, in Fukushima in where people are allowed to live are low enough," Hayano says.