(This has been cross-posted)
I attended the talk at Temple Univ. in Tokyo on Tues. night (July 3), at which Dr. Ryu Hayano, Nicholas Sternsdorff, and Satsuki Takahashi spoke. I was particularly interested in hearing what Dr. Hayano had to say, because he has been spearheading many important efforts in Fukushima, such as measuring the radiation in school lunches and measuring people's internal contamination with whole body counters. His name has come up quite often here. His work has been extremely conscientious and reliable, and has brought him into conflict with the government and his university at several points. His presentation was a model of clarity, and he engaged the audience very well by dotting it with questions which we answered by holding up sheets of paper with "T" or "F." *Such as, "About 10% of food from Fukushima has exceeded the 100Bq/kg standard," *(F, only 2%), and "No milk from Fukushima has been shown to be contaminated" (T, none has). His slides are available here:
http://www.slideshare.net/safecast/temple-u-20120703
Hopefully a video of his talk will be posted soon as as well. I'd like to give a brief summary of what he said.
--Their WBC measurements in Minamisoma and Hirata have been very extensive and accurately performed. *Between Nov 2011 and May 2012 they've measured about 10,000 people. In Hirata, about 15,000 people have been measured. The vast majority have shown no internal contamination. The levels of others has been extremely low compared to people in Russia, Ukraine, and Belarus 5-10 years after the Chernobyl accident. In fact the levels are much lower than the average internal contamination of Japanese people measured in 1964 at the height of nuclear weapons testing. More on that below.
--He spoke a lot about calibration issues and how they solved them. He said that around the end of last year, CRMS, who had been conducting WBC measurements in Fukushima, was about to release a report claiming that the entire population of Fukushima had 20Bq/kg of internal cesium contamination. Dr. Hayano insisted on re-analyzing the data himself to see if their measurements were accurate or not. By calibrating their machine with a plastic "phantom" known to have 0Bq/kg, he determined that their reading of "20" should have been "0." He likened it to using a scale that was set to "20kg" when no weight was on it to weigh people. So the internal contamination of almost everyone CRMS had measured was 0Bq/kg! *This has been borne out in subsequent measurements. (Imagine what we'd be dealing with if CRMS had released that report!)
--They have remeasured everyone who showed internal contamination after a period of months, and based on that have shown that in almost every case people's body burden of cesium has been sharply decreasing; the slopes of the decrease indicate that most of these people are consuming close to 0 Bq/day. Therefore he concludes that the food screening has been very effective. *Of 10,000 people only 2 showed an increase between Nov 2011-May 2012, and they were farmers who have been eating a lot of their own food.
-- "Duplicate portion" measurements of food were conducted with 100 families in Fukushima in April 2012. Only 10 consumed any contaminated food; of those, only one family received more than 10Bq/kg --12 Bq/kg to be exact (the natural radioactive potassium each family consumed however ranged from about 20-50 Bq/kg). Based on the WBC measurements and these studies he expects that very few people in Fukushima will have more than 0.01mSv/yr internal exposure. This is so vastly lower than the 100mSv/yr risk level or even the stricter 10mSv/yr level promoted by others, that he concludes that "there is no health risk." This is an unpopular stance as we all know, but it's based on very solid measurements.
--Only 2% of the 53,000 food samples tested by local gov'ts since the new 100 Bq/kg standards came into effect have exceeded this standard. *No milk from Fukushima has been shown to be contaminated yet; no contamination has been found in school lunches in Minamisoma since they started measuring them in Jan 2012.
--On the other hand, soil in Fukushima is very contaminated, and items like wild boar, wild berries, etc. show high levels, so people will have to be very careful to continue effective monitoring for years to come.
--Because the internal contamination has been so low, he thinks that external contamination may present a relatively greater risk (but still very small). Based on glass badge results from Fukushima City, Minamisoma City, Koriyama City, and Soma City, most people there are receiving less than 1mSv/yr.
--In 1964, due to nuclear testing, the entire population of Japan was consuming 5 Bq/kg of Cs137 in their food every day, and this continued for over a year, with average body burdens of 550 Bq. This is much greater than the average levels they have seen in Fukushima so far. He suggested that the exposure in 1964 has not been directly linked to any measurable increase in illness, even after almost 50 years, and that the Fukushima exposures will not either.
--Afterward, I asked him his opinion about the recent WHO report on exposures, and he got very agitated and said it was terrible, because it overestimated exposures so blatantly. *He will be bringing his findings to the UN in a few weeks to push for the data to be included in the WHO Fukushima health risk report due out in a few months.