Which radiation dose did persons receive who were in Japan when the reactor accident of Fukushima happened?

After their return from Japan, some persons requested the BfS and other Laboratories for Incorporation Monitoring to carry out measurements for possible contamination. In the period immediately following the accident, small amounts of incorporated radionuclides (iodine-131, iodine-132, tellurium-132, caesium-134 and caesium-137) were measured in the body in some cases. Furthermore, contamination on clothing was occasionally detected. The highest level of radiation exposure due to incorporated radionuclides in one individual person was about 0.5 millisievert.

All other doses received were clearly below this value. In comparison, the average natural radiation exposure in Germany is 2.1 millisieverts per year and can increase to over 5 millisieverts depending on local conditions. The additional radiation exposure in the measured persons can thus be classified as low. There has never been a risk for outsiders who are in contact with these groups of people.

In the meantime, comprehensive measurement data related to the incorporation of radionuclides as a consequence of the Fukushima accident among the Japanese population are available. These data demonstrate that additional radiation exposure from incorporation of radioactive substances is non-existent or very low.