Will you temporarily stop purchasing Japanese Greens?

[Xell]

This sounds bad, since for most people there are no safe limits, especially when there is choice. I wonder if they did found something else expect cesium. From what i remember, cesium is still not that dangerous. It doesn't stay in body for long time.

Because of its beta decay (to 137mBa), 137Cs is a strong emitter of gamma radiation.[41] Its half-life makes it the principal medium-lived fission product along with 90Sr—both are responsible for radioactivity of spent nuclear fuel after several years of cooling up to several hundred years after use.[42] For example 137Cs together with 90Sr currently generate the largest source of radioactivity generated in the area around the Chernobyl disaster.[43] It is not feasible to dispose of 137Cs through neutron capture (due to the low capture rate) and as a result it must be allowed to decay.[44]
Almost all caesium produced from nuclear fission comes from beta decay of originally more neutron-rich fission products, passing through various isotopes of iodine and of xenon.[45] Because iodine and xenon are volatile and can diffuse through nuclear fuel or air, radioactive caesium is often created far from the original site of fission.[46] With the commencement of nuclear weapons testing around 1945, 137Cs was released into the atmosphere and then returned to the surface of the earth as a component of radioactive fallout.[7]

I read it many times, the thing is about cesium 137. It doesn't accumulate in human body, some of other elements can stay for much longer periods. That's the point here. Radiation from this amount of cesium is really small, danger is from inner long term exposure. For example Chernobyl, studies show many confirmed health problems from iodine that was released in first days and nothing from cesium 137.


p.s.
Found health safe level in Japan for cesium 137, it's 500 becquerels per kg. But even so, i would not drink it on purpose while i can get same thing without any contamination.

[a.serrao]

[...] It doesn't accumulate in human body [...]

That's not correct.
Cs-137 actually stays in the human body for 70 days.

[tjsan]

Gastrointestinal absorption from food or water is the principal source of
internally deposited cesium in the general population. Essentially all cesium that is ingested is absorbed into
the bloodstream through the intestines. Cesium tends to concentrate in muscles because of their relatively
large mass. Like potassium, cesium is excreted from the body fairly quickly. In an adult, 10% is excreted
with a biological half-life of 2 days, and the rest leaves the body with a biological half-life of 110 days.
Clearance from the body is somewhat quicker for children and adolescents. This means that if someone is
exposed to radioactive cesium and the source of exposure is removed, much of the cesium will readily clear
the body along the normal pathways for potassium excretion within several months.

Found in www.evs.anl.gov/pub/doc/Cesium.pdf

[a.serrao]

Found in http://www.evs.anl.gov/pub/doc/Cesium.pdf

That's correct I suppose.

[Xell]

[...] It doesn't accumulate in human body [...]

That's not correct.
Cs-137 actually stays in the human body for 70 days.

It is correct, it doesn't accumulate, in about 30 days most of it will be gone. 70 days is for full cleaning. But if it would be strontium, it can accumulate in bones and stay with you for years, especially kids affected by this, cesium on the other hand is getting out from kids even faster, than adults.

[a.serrao]

[...] It doesn't accumulate in human body [...]

That's not correct.
Cs-137 actually stays in the human body for 70 days.

It is correct, it doesn't accumulate, in about 30 days most of it will be gone. 70 days is for full cleaning. But if it would be strontium, it can accumulate in bones and stay with you for years, especially kids affected by this, cesium on the other hand is getting out from kids even faster, than adults.

Quite the opposite of what you say.
See this: http://www.ippnw.ch/content/pdf/Sympo_1 ... hevsky.pdf
Cs-137 bioaccumulates, no matter what.

[a.serrao]

Radioactive substances above the legal limits have been detected in tea leaves harvested in 3 municipalities in Kanagawa Prefecture, neighboring Tokyo.

The prefectural government is checking samples of tea leaves harvested in 15 municipalities in the region. 570 becquerels of radioactive cesium per kilogram, exceeding the provisional state limit of 500, were detected in products from Minami-Ashigara City on May 9th.

Officials say that radioactive cesium has been detected in 3 of the 8 samples it has checked so far. The 3 highest readings were 780 becquerels in tea leaves harvested in Odawara City, 740 becquerels in Kiyokawa Village and 670 bequerels in Aikawa Town.

The Kanagawa prefectural government has asked the 3 municipalities and the local farmers' association to voluntarily halt shipments for the time being.

Prefectural officials will hold meetings for farmers on Friday and Saturday to show them how to dispose of contaminated leaves and how to grow tea safely.
Friday, May 13, 2011 15:57 +0900 (JST)

NHK

[Kevangogh]

Amounts exceeding 500 becquerels (the legal limit) were NOT found in the tested areas of: Fuji, Numazu, Izu, in the far eastern zone in Shizuoka.

More results coming in the next few days. No, I don't know the exact becquerels found in those areas, only that it did not exceed 500.

Edit: Shimizu was also clear. Kanegawa is actually quite some distance from Shizuoka. I also have a paper in my hand - Uji is clear and I'm sure Kagoshima is as well.

[Kevangogh]

For some perspective, the permissible level of cesium is set at 500 for Japan & the EU. The USA is 1200, while the international standard 1000.

[a.serrao]

For some perspective, the permissible level of cesium is set at 500 for Japan & the EU. The USA is 1200, while the international standard 1000.

Thanks Kevin for making things clear. This is of the utmost importance right now.

[Xell]

Quite the opposite of what you say.
See this: http://www.ippnw.ch/content/pdf/Sympo_1 ... hevsky.pdf
Cs-137 bioaccumulates, no matter what.

I'll ask about this document. What i wrote is from words of a specialist about radioactive hygiene.

[a.serrao]

No need to worry about this. But for the sake of completeness I can link this news: http://www3.nhk.or.jp/daily/english/17_26.html
Tea growers in Ibaraki halt shipments

[a.serrao]

Shizuoka, Kanagawa governments oppose radiation screening order for tea leaves


The Shizuoka and Kanagawa prefectural governments have called on the Ministry of Health, Labor and Welfare to withdraw its request for local authorities in northeastern and eastern Japan to check radiation levels in green tea leaves during processing.

After the amount of radioactive cesium exceeding the legal limit was detected in green tea leaves harvested in Ibaraki and Kanagawa prefectures, the health ministry ordered Tokyo and 13 prefectures in northeastern and eastern Japan on May 16 to ban shipments of half-processed steam dried green tea leaves, known as "Aracha," if cesium tops the national permissible limit of 500 becquerels per kilogram.

The cesium concentration in steam dried green tea can become about five times as high as that in raw leaves, prompting the ministry to order the prefectures to check radiation levels in Aracha.

However, the move met with opposition from Shizuoka and Kanagawa prefectures.

Shizuoka Vice Gov. Yoichiro Iwase visited Minister of Health, Labor and Welfare Ritsuo Hosokawa on May 17 and requested, in writing, that the measurement of radiation doses be limited to raw green tea leaves and those ready to be marketed.

Iwase pointed out the fact that consumers do not drink Aracha and that radiation levels in green tea can exceed the legal limit during the production process even if those in raw leaves and final products are below the provisional amount.

On the same day, Kanagawa Gov. Yuji Kuroiwa submitted a petition to the health minister and the agriculture, forestry and fisheries minister, requesting Aracha be excluded from radiation screening.

[Flonihoncha]

Here's the results of the tests proceed in several places of Shizuoka Prefecture on may 12,13&14.
On raw leaves, the highiest cesium rate is 138.77Bq/kg (shimizu), and the lowest is 39.83Bq/kg (kakegawa city).
But in the brewed liquid (the limit is fixed at 200Bq/kg), you have 10.81Bq/kg for the highest (Shimizu city), and 3.99Bq/kg (Kakegawa city) for the lowest. (10g for 430cc of 90°C, 1minute)

[Lionel]

I am not a chemist but I made some maths...
For the leaves from Shimizu/Shizuoka measured at 138.77 Bq/kg leaves for Cesium.
Becquerel is an emission unit for radiation. Sievert (mSv or µSv) is a unit that takes effects on the human body into account. To switch from Becquerel to Sievert, I do the operation :
Becquerel x dose factor = Sievert.
For Cesium, the dose factor is a constant = 0.000014.
So for this kg of leaves : 138.77 x 0.000014 = 1.9 µSv/kg leaves.
The medium annual natural radiation dose in France (where I live) is : 2400 µSv.
So if I absorb 1 kg of those Shizuoka leaves, I absorb 1.9 µSv = 0.08% of the medium annual dose.
(1 cigarette = 7µSV. A Paris-New York flight = 80 µSv).
So these figures express a very low contamination.
And this is for the leaves, we don't absorb the leaves but the liquid, for which the figures must by divided by 10.

This short calculations