A movement calling on people to retain their children's baby teeth to help study radiation exposure in the wake of the Fukushima nuclear disaster is gaining momentum in Japan.
The radioactive material strontium-90 is easily absorbed into baby teeth, and last year a group of experts formed the "Preserving Deciduous Teeth Network (PDTN)," urging people to keep their children's baby teeth.
"Baby teeth are evidence of exposure to radiation. We urge people to keep them for the future," says Takemasa Fujino, 67, a joint head of the network.
Fujino is president of a medical institution that operates three dental clinics in the Tokyo metropolitan region. One clinic is in Matsudo, Chiba Prefecture, which was regarded as a "hot spot" with relatively high levels of radiation following the March 2011 outbreak of the Fukushima No. 1 Nuclear Power Plant disaster.
With residents feeling uneasy, in 2011 Fujino began calling for people to preserve their children's baby teeth, wanting to do something as a dentist to protect children's lives and health.
So far, Fujino has had about 500 baby teeth donated, and has commissioned a Swiss testing facility to analyze some of them. Next year the network plans to establish its own testing facility in central Japan.
Baby teeth are formed from when the child is in the womb. "The teeth of children that were fetuses five years ago at the time of the accident will be coming at about this point exactly, and the movement to preserve them will become even more important," Fujino says.