Radioactive iodine spread much further south from Fukushima than originally believed.

A Japanese government survey published on Thursday the 22th of September, showed that radioactive iodine emitted from the Fukushima Daiichi nuclear plant spread not only northwestward but also to the south of the plant.

The ministry of science sampled soil at 2,200 locations, mostly in Fukushima Prefecture, but also as far south as Tokyo in June and July, and created another map indicating the extent of the radioactive contamination as of June 14th.
This map is giving information about radioactive contamination that where not previously published nor know by the public or even government workers.
Officials were able to obtain data for iodine 131 at only 400 locations, because of its short half-life of 8 days and because they waited to long to start collecting data on iodine 131.

The latest map shows that iodine 131 spread northwest of the plant, just like cesium 137 as indicated on an earlier map. But the substance was also confirmed south of the plant at relatively high levels.
The researchers found that accumulation levels of iodine 131 were higher than those of cesium 137 in coastal areas south of the plant.

Officials of the ministry said the clouds that moved southward over the plant apparently caught large amounts of iodine 131 that were emitted at the time.

Iodine 131 could cause thyroid cancer through internal exposure. The ministry is therefore trying to determine at what levels the substance spread immediately after the accident at the plant in March. 
Six month after the nuclear disaster at the Fukushima dai ichi plant it is starting to become clear that high level of radioactive Cesium 137 as well as radioactive iodine 131 have contaminated large areas of the prefecture of Fukushima and reached as far North as Hokkaido and as far south as Tokyo prefectures leaving hot spots with well over the maximum permissible safety limits of radioactive elements. Contaminating soil, lac's, rivers and the ocean to a far greater extend than previously believed. 
Still, many areas in the 300 km radius from the Fukushima plant have not been sampled to this day nor has any form of assessment taken place. In stead people are being told that all is fine and that they should not worry. Why so many are taking things into their own hands, trying to assess the amount of radiation their area or town received.
This in some cases could lead to false data and needless fear mongering. Why it is of the outmost importance that all areas be tested and that an accurate map be made public so that the public can make an educated and objective assessment of their own and decide on the actions they want to have implement.