[cperciva]

Will nothing change at all, except for a small rise in cancer rates for people who live next to the plant?

Nothing will change at all, even for people who live right next to the plant.

Someone sitting at the front gate of the plant for the past week would have absorbed approximately 100 mSv of radiation. This is a significant amount -- equal to the recommended annual limit for radiation workers -- but too low to cause radiation sickness (symptoms of acute radiation sickness start at between 250 and 500 mSv).

The cancer risk from radiation is roughly 0.01 cancers per Sievert, so this individual would have a 0.1% increase in his chance of getting cancer. People living further away would naturally have even lower probabilities of developing cancer.

Based on the population density of the surrounding area, there is a low probability of any cancers being caused by the Fukushima nuclear incidents, even if the residents had not been evacuated.

(Does this mean that the residents should not have been evacuated? No. It means that the evacuations were a precautionary measure to keep them safe in case the situation got worse than it has in fact gotten.)

[kenjackson]

What about the amount from those TSA machines under normal operation and the amount apparently emitted by mistake recently?

[elliottcarlson]

It would have been helpful to get that number on that chart - just because it would help dispel bad information about the backscatter x-rays as well. The regular amount of radiation emitted by one of those machines is 0.1µSv (according to the chart - equivalent to eating a banana). The supposed mistake would have made the emissions 10 times higher (couldn't find a real µSv reading, just the 10x statement[1]) which would be 1µSv, or the same as using a CRT monitor for a year.

[1] http://www.wired.com/threatlevel/2011/03/tsa-radiation-test-...