Symposium 2013 Ian Fairlie

Assessing long-term Health Effects from Fukushima’s Radioactive Fallout – Dr Ian Fairlie

“…..Fukushima’s second anniversary in March 2013 is an opportune moment to assess its likely long-term consequences, although the accident is by no means over given the precarious state of the four wrecked reactor buildings – especially the spent fuel pond at Unit 4.

The figure below (reproduced from the French Government’s Institut de Radioprotection et de Sûreté Nucléaire (IRSN 2011)) indicates the extent of the radioactive fallout from Fukushima’s explosions and gaseous emissions in areas near Fukushima. In addition, lower concentrations fell over other areas of Japan, over neighbouring countries and eventually circulating the Northern Hemisphere.

Exposure to radioactive fallout will result in radiation doses to the people living in these areas and this post will attempt to estimate future cancer deaths arising from these doses. Population doses are usually termed collective doses…….

First, it is important to realise that air emissions from Fukushima are much more important, in terms of health effects, than Fukushima’s sea discharges…….

In areas near Fukushima, most of the long-term dose to the public originates from Cs-134 and Cs-137 isotopes which fell from Fukushima’s plumes to the ground. These have longish half-lives (2 years for Cs-134 and 30 years for Cs-137) and they irradiate people with gamma and beta rays. This is called groundshine. Smaller doses originate from being immersed in the plume, from eating contaminated food and drinking contaminated water. In areas further away, the situation is reversed with most of the dose coming from ingestion and lesser amounts from groundshine…….

It’s important to realise that the use of 2.4 and 38 year soil weathering half lives means that groundshine doses from Fukushima (and Chernobyl) last more than 70 years – ie a lifetime. Many scientists remain unaware of this implication but it is based on good evidence.

The dose consequences are shown in graphical form in figure 1 below (reproduced from Beyea et al, 2012) which shows that, after 75 years, the total collective dose from groundshine is about 6.5 times greater than the groundshine dose received in the first year. Unfortunately the recent second WHO (2013) report on the health risks from Fukushima used a factor of 2 and not 6.5: one of a number of deficiencies in its report.