One of the interesting features of the hysteria about the nuclear disaster at Fukushima has been that the dire predictions of mass die offs have all been in the future. No one's actually been able to point to anyone who has been harmed by the radioactive releases so far.

Now of course, it could indeed be that the future holds some untold as yet horrors but we're beginning to see careful scientific research coming out about what the actual radiation doses have been. That careful scientific research is giving us answers rather different from those that cable TV have been proffering.

For example, this came out in Proceedings of the National Academy of Sciences (PNAS) yesterday. It's a study of how much radiation the people living around the Fukushima plant itself were exposed to. The conclusion?

There is a potential risk of human exposure to radiation owing to the March 2011 Fukushima Daiichi Nuclear Power Plant accident. In this study, we evaluated radiation dose rates from deposited radiocesium in three areas neighboring the restricted and evacuation areas in Fukushima. The mean annual radiation dose rate in 2012 associated with the accident was 0.89– 2.51 mSv/y. Themean dose rate estimates in 2022 are comparable with variations of the average 2 mSv/y background radiation exposure from natural radionuclides in Japan. Furthermore, the extra lifetime integrated dose after 2012 is estimated to elevate lifetime risk of cancer incidence by a factor of 1.03 to 1.05 at most, which is unlikely to be epidemiologically detectable.

That last line means that we'll never be able to measure things accurately enough to know whether anyone at all has actually died as a result of radiation exposure from this accident. Or at least, given that this experiment was about the areas around the plant then among people from areas around the plant.

But, I hear the cry, but what about bioaccumulation? What about all that stuff that went into the ocean and is now moving up the food chain? Won't that make, say fish caught off the US dangerous? Fortunately this is something that other researchers have already looked at, in PNAS again as it happens.

Radioactive isotopes originating from the damaged Fukushima nuclear reactor in Japan following the earthquake and tsunami in March 2011 were found in resident marine animals and in migratory Pacific bluefin tuna (PBFT). Publication of this information resulted in a worldwide response that caused public anxiety and concern, although PBFT captured off California in August 2011 contained activity concentrations below those from naturally occurring radionuclides. To link the radioactivity to possible health impairments, we calculated doses, attributable to the Fukushima-derived and the naturally occurring radionuclides, to both the marine biota and human fish consumers. We showed that doses in all cases were dominated by the naturally occurring alpha-emitter 210Po and that Fukushima-derived doses were three to four orders of magnitude below 210Po-derived doses. Doses to marine biota were about two orders of magnitude below the lowest benchmark protection level proposed for ecosystems (10 μGy·h−1).

Consumption of 200 g (a typical restaurant-sized serving) of PBFT contaminated with 4.0 Bq·kg-1 dry weight of 134Cs and 6.3 Bq·kg-1 dry weight of 137Cs (mean values for PBFT caught off San Diego in August 2011) resulted in committed effective doses of 3.7 and 4.0 nSv, respectively (Table 1). To put this into perspective, the combined dose of 7.7 nSv from these two Cs isotopes is only about 5% of the dose acquired from eating one uncontaminated banana (assuming 200 g weight) and absorbing its naturally occurring 40K (28), and only about 7% of the dose attributable to the 40K in the PBFT (Table 1).

Again, simply too low for anyone to worry about at all. Or, as another part of the paper put it:Or to put that in another manner, the extra radiation from eating pacific blue fin tuna contaminated as a result of Fukushima is equal to the extra risk of eating one single dried banana chip from Trader Joe's.

Really, the lesson to be had about nuclear power from the Fukushima disaster is how amazingly safe the whole technology is. Horribly expensive, of course, but remarkably safe.

[Image courtesy Thinkstock]