Consequences for people and environment
The emissions of radioactive contamination to the air were substantial during the first few days after the accident, but much of the radioactive material that reached the atmosphere was carried out over the Pacific Ocean by the wind, and fell down far from land. Contamination by radioactive fallout over land was therefore limited to areas in northern Japan (6). No other countries were exposed to radioactive fallout of any significance. The counter-measures employed by the Japanese authorities consisted of advice to stay indoors or to evacuate from contaminated areas, prophylactic distribution of iodine tablets for children, and food restrictions. From 12 March, the day after the earthquake, the population in a radius of 20 km around Fukushima Dai-ichi was evacuated. The evacuation zone was later increased to a radius of 30 km.
About 20 000 inhabitants in Fukushima prefecture were monitored for radioactive contamination, and radioactive contamination had to be removed from the bodies and clothes of 102 of these persons. After the decontamination, the radioactivity was reduced so much that there were no grounds for concern about health consequences for these persons (6).
At the end of March, 1 080 children aged 0 – 15 years in the most contaminated areas were examined for uptake of radioactive iodine. None of the children who were examined had received doses of over 100 mSv to the thyroid gland, which is Japan’s limit for recommending use of iodine tablets (6). It should be noted that the limit in Norway is 10 mSv, so some of these children would have been recommended to take iodine tablets in Norway. Time will show whether there will be an increase in cases of thyroid cancer in children in Japan, as was the case after the Chernobyl accident (5).
A number of readings of water samples, agricultural products and seafood that were carried out in March showed high levels of radioactivity, which led to the introduction of food restrictions (7).
Substantial areas of land both inside and outside the evacuation zone have been contaminated, first and foremost by radioactive caesium, which has a half-life of about 30 years (7). This contamination will have to be eliminated before people can move back to the most contaminated areas.
As in the aftermath of the Chernobyl accident, the greatest radioactive contamination has been found in an area of some tens of kilometres around the power plant (8). Only long-term surveillance and research will show what consequences this situation will have on land and for the coastal marine eco-system in this area.