I have been following the radiation situation in Japan carefully and with some concern. I follow blogs like 'enenews' and 'ex-skf' which collect news from various sources and translate it into english. I've also been reading about the health effects of radiation. And of course we've been using our geiger counter. Here are some observations.
1. Distribution of contamination. his is the radiation contour map produced by Professor Hayakawa of Gunma University:
The main area of contamination is of course in Fukushima prefecture, to the north and west of Fukushima Daiichi. The situation in Fukushima prefecture is obviously extremely serious, and much worse than Tokyo. We frequently read reports of high levels of radiation and contamination above the thresholds at which Russia evacuated areas after Chernobyl, and I don't understand why the government hasn't evacuated children from a much wider area.
Less intense, but more worrying for us in Tokyo, is the ridge of contamination extending south across Ibaraki and Chiba prefectures, to the eastern suburbs of Tokyo.
In the map below you can also see a hotspot on the east coast of Izu at Ito, on the other side of Mt Amagi from where Baba lives (just to the right of the red arrow below). Looks like a radioactive plume drifted south across Tokyo bay and Sagami bay, and some precipitated out when it hit Mt Amagi in Izu.
This is Ministry of Education's aerial survey map of cesium 134 and 137 contamination.
And the detail for theTokyo metropolitan area below. "most of Tokyo has less than 10,000 becquerels/square meter of radioactive cesium, with the exception of the western-most Okutama and the eastern special wards ("ku") bordering Chiba Prefecture to the east". (Ex SKF 8-Oct-11). Okutama is a mountainous area, with the reservoirs supplying Tokyo's drinking water.
At first sight this seems relatively reassuring. However the aerial surveys have been criticized for underestimating the contamination and for averaging out 'hotspot' concentrations, so ground measurements are more relevant where available.
Fortunately, the annual Tokyo Metropolitan government survey of soil contamination in Shinjuku was recently released. The soil sample was taken at Tokyo Metropolitan Institute of Public Health in Hyakunin-cho, Shinjuku-ku, where the official air radiation level is monitored every day for Tokyo. This is a few km north of where we live.
EX SKF reports: "Numbers for the soil from the surface to 5 centimeters deep were: Iodine-131: ND, Cesium-134: 360 becquerels/kg, Cesium-137: 430 becquerels/kg, Total cesium: 790 becquerels/kg. To convert from "per kilogram" to "per square meter", Japan's Nuclear Safety Commission uses the factor of 65. The total cesium per square meter in Shinjuku therefore is: 51,350 becquerels per square meter. Even if you just take cesium-137 (for comparison purpose), 430 becquerels/kg translates to 27,950 becquerels/square meter. "
For comparison, I note that in Yablokov's book about Chernobyl, a common threshold for classifying areas as contaminated was 1 Ci/km of Cesium-137, which is equivalent to 37,000 Bq/m2. (not other radio-nucleids like Cs-134 are ignored in this measure). "Some 23% of the area of Belarus (47,000km2), was contaminated by Cs-137 at a level higher than 1 Ci/km2. Until 2004 the density of Cs-137 contamination exceeded 37 kBq/m2 in 41,100km2" (p7). So if Im not mistaken, levels above 37kBq/m2, are equivalent to the most contaminated quarter of Belarus after Chernobyl! Or the most contaminated 5% of Ukraine.
Nevertheless Tokyo's official air radiation measurements, taken at the same site, and published daily are always around 0.07 micro Sv/h (see http://monitoring.tokyo-eiken.go.jp/monitoring/graph.html), which is low background levels.
Here are some other examples of soil measurements from areas near Tokyo not considered particularly 'hot' in the radiation maps:
EX-SKF 19-Sep: "63,000 Bq/Kg of Radioactive Cesium from Rooftop of Apartment Bldg in Yokohama City. It made the national news ONE MONTH AFTER a private citizen measured the air radiation level on his own and had the dirt tested with his own money. According to TV Asahi's "Morning Bird" news variety show on September 19, 63,000 becquerels/kg of radioactive cesium was detected from the dirt sediment on the rooftop of a 5-story apartment building in Kohoku-ku in Yokohama City. It is the same Kohoku-ku where 42,000 becquerels/kg of radioactive cesium was found near the side drain on the road." The air radiation at the spot was 1.8 microsievert/hour, and the Cs-137k component was 33kBq/m2 which I note for comparability is just below the Russian 37k threshold.
On 23-Sep EX-SKF reported another apartment roof with 106k Bq/m2, of which 55k CS-137.
8-Oct EX-SFF report Strontium-90 was found in Yokohama by an independent journalist. Until now Strontium-90 had not been found more than 80km from Fukushima DaiIchi - so the Ministries don't test for it.
EX-SKF 19-Sep: "63,000 Bq/Kg of Radioactive Cesium from Rooftop of Apartment Bldg in Yokohama City. It made the national news ONE MONTH AFTER a private citizen measured the air radiation level on his own and had the dirt tested with his own money. According to TV Asahi's "Morning Bird" news variety show on September 19, 63,000 becquerels/kg of radioactive cesium was detected from the dirt sediment on the rooftop of a 5-story apartment building in Kohoku-ku in Yokohama City. It is the same Kohoku-ku where 42,000 becquerels/kg of radioactive cesium was found near the side drain on the road." The air radiation at the spot was 1.8 microsievert/hour, and the Cs-137k component was 33kBq/m2 which I note for comparability is just below the Russian 37k threshold.
On 23-Sep EX-SKF reported another apartment roof with 106k Bq/m2, of which 55k CS-137.
8-Oct EX-SFF report Strontium-90 was found in Yokohama by an independent journalist. Until now Strontium-90 had not been found more than 80km from Fukushima DaiIchi - so the Ministries don't test for it.
2. Our geiger counter measurements
Our geiger counter has consistently recorded higher readings than the official measurements. This could be due to the calibration of our relatively cheap instrument. On the other hand it is consistent with Prof Hyakawa's map, where our area of Tokyo is light green (0.12 micro sv/h) to dark green (0.25 u sv/h)
However, we are also observing a rising trend, which contrasts to the low and declining official readings.
When we first got our geiger, most readings were in a range 0.05 micro sv/h to 0.15 micro sv/h, and while we occasionally got readings up to 0.25 uSv/h (obvious malfunctions notwithstanding), we didn't notice readings above drains to be much higher. Now the readings are regularly from 0.15 to 0.25 and more often in the 0.30s uS/h.
In mid-Sep, on the way to the sports center, I quietly tested the gutter outside Dad's favorite wine shop in Hatsudai, where rain clearly pools. Average of 4 readings was 0.35 usv/h , with the highest 0.39, which the Russian geiger classifies as 'high background'. Another gutter near the sports center also gave readings in the mid 0.30, while the air level was generally around 0.2 usv/h.
Some readings taken today:
Our terrace (after last nights rain): 0.3, 0.14, 0.13, 0.19, 0.27, 0.15, 0.23, 0.39, 0.13, 02.7 = average of 0.22 uSv/h
Dining room table (near terrace): 0.23, 0.16, 0.19, 0.12, 0.22, 0.13, 0.21, 0.20, 0.15, 0.09 = average of 0.17 uSv/h
Hepa air filter (further indoors): average of 0.13 uSv. This is reassuring - no evidence of airbourne contamination being conventrated in the air filter.
This suggests to me that the air is relatively clean, inside at least, but there is a level of contamination building up on the ground due to rainfall.
This suggests to me that the air is relatively clean, inside at least, but there is a level of contamination building up on the ground due to rainfall.
3. Food contamination
Again from Ex-SKF although widely reported in the press.
"Shizuoka Prefecture announced on October 7 that 1,033 becquerels/kg of radioactive cesium exceeding the provisional safety limit of 500 becquerels/kg was found in the dried shiitake mushrooms produced and processed in Izu City in Shizuoka. It was found by a voluntary testing by a retailer. The prefectural government plans to conduct its own testing of the remaining products kept at the producer on October 8."
This is interesting because Izu city is where Baba lives, 250+ km from Fukushima and is supposed very low radiation area, (despite the hotspot in Ito on the other side of Mt Amagi). Also note that it was discovered by voluntary testing not official screening. Mushrooms are believed to concentrate radiation and we don't eat them, except those from one company that does checks an guarantees its produce below 10 bq/kg (Yuki Kuni in Nagano).
Rika is buying food from suppliers in west Japan or who guarantee produce is tested. However we still eat-out frequently.
4. Health effects of Radiation
I've been reading about the health effects of radiation and there is clearly controversy between the official industry-dominated bodies like the ICRP and UNSCEAR, and some less mainstream researchers like Chris Busby and Alexy Yablokov.
The ICRP model suggests that the radiation we are observing in Tokyo is unlikely to be a threat to health. United Nations Scientific Committee of the Effects of Atomic Radiation (UNSCEAR) report on Chernobyl. They estimate relatively few deaths, concentrated minly in 5,000 additional cancer deaths "among the 600 000 persons receiving more significant exposures (liquidators working in 1986–87, evacuees, and residents of the most contaminated areas)".
"Among the residents of Belarus, the Russian Federation and Ukraine, there had been up to the year 2005 more than 6,000 cases of thyroid cancer reported in children and adolescents who were exposed at the time of the accident.... most likely caused by radiation exposures shortly after the accident [of which 15 deaths] Apart from this increase, there is no evidence of a major public health impact attributable to radiation exposure two decades after the accident. There is no scientific evidence of increases in overall cancer incidence or mortality rates or in rates of non-malignant disorders that could be related to radiation exposure. The incidence of leukaemia in the general population, one of the main concerns ... does not appear to be elevated. "
On the other hand studies cited in Yablokov book, find a much greater increase in a wide range of cancers and other health risks due to Chernobyl.
"Among the residents of Belarus, the Russian Federation and Ukraine, there had been up to the year 2005 more than 6,000 cases of thyroid cancer reported in children and adolescents who were exposed at the time of the accident.... most likely caused by radiation exposures shortly after the accident [of which 15 deaths] Apart from this increase, there is no evidence of a major public health impact attributable to radiation exposure two decades after the accident. There is no scientific evidence of increases in overall cancer incidence or mortality rates or in rates of non-malignant disorders that could be related to radiation exposure. The incidence of leukaemia in the general population, one of the main concerns ... does not appear to be elevated. "
On the other hand studies cited in Yablokov book, find a much greater increase in a wide range of cancers and other health risks due to Chernobyl.
"In 20 years it has become clear that now fewer than 8 million inhabitants of Belarus, Ukraine, and Russia have been adversely affected. One must understand that in areas contaminated above 1Ci/km2 (a level that undoubtedly has statistical impact on public health) there are no fewer ten 1 million children. " [Yablokov, p25, note 1 Ci/km2 = 37k Bq/m2]
Based on this Chris Busby predicts a public health catastrophe in Japan as a result of Fukushima
Yablokov and Busby are clearly considered 'fringe' by the nuclear scientific establishment, and don't get much exposure in mainstream media. Their work is heavily criticized on Wikipedia articles etc, Chris Busby is interviewed on TV, but mainly by 'Russia Today', not, say, the BBC. Nevertheless Yablokov's book is endorsed by the US nuclear engineer and commentator Arnie Gundersen, who so far has been a lot more reliable on the crisis than the official announcements.
In Japan there are also a group of serious independent Japanese academics who are clearly extremely concerned.
In Japan there are also a group of serious independent Japanese academics who are clearly extremely concerned.
My general impression is that there is huge pressure on the media in Japan and elsewhere to downplay the health risks, as well as a cultural resistance in Japan to speak out and risk upsetting others who are 'staying calm and carrying on'. So worrying raw data is released, but then seems to sink with little comment from the mainstream media, and only fringe commentators are making comparisons with the Chernobyl and extrapolating serious health consequences.
Also the reassuring official statements seem more like PR with inconsistencies and evasions. I see a vacuum in the media where Id hope to see credible independent experts putting their reputations on the line to back the government view, and convincingly defend the ICRP model. Maybe I'm just missing this because Im using too many fringe news sources.
Also the reassuring official statements seem more like PR with inconsistencies and evasions. I see a vacuum in the media where Id hope to see credible independent experts putting their reputations on the line to back the government view, and convincingly defend the ICRP model. Maybe I'm just missing this because Im using too many fringe news sources.
5. Some links:
http://www.euradcom.org/2011/ecrr2010.pdf
European Committee for Radiation Risks (Chris Busby). This committee was set-up by the Green group in the european parliament to provide an alternative research voice as the ICRP was seen as too dominated by the nuclear industry.
http://www.euradcom.org/2009/lesvostranscript.htm
Former head of the ICRP discussing shortcomings of ICRP model with Chris Busby.
http://www.strahlentelex.de/Yablokov%20Chernobyl%20book.pdf
Yablokovs book on Chernobyl, published but not peer reviewed by the NY Academy of Sciences. It cites hundreds of studies, mainly from eastern europe which report large and sometimes dramatic, increases in a wide range of health problems in the contaminated areas. The book and papers cited have been criticized lacking formal statistical tests proving the statistical significance of the results and linkages to radiation doses. It has also been argued that the adverse health outcomes - like a 8 year drop in life expectancy in Belarus - were due to other factors.
Having read the book, I find the number and size of the effects compelling even without statistical tests. Unless this is a gross misrepresentation and distortion of the data, the dangers of radiation are much higher than the ICRP and UNSCEAR predict. The question is how much higher....
Having read the book, I find the number and size of the effects compelling even without statistical tests. Unless this is a gross misrepresentation and distortion of the data, the dangers of radiation are much higher than the ICRP and UNSCEAR predict. The question is how much higher....
