Saturday, April 28, 2012

(UPDATED) 66 Bq/Kg of Radioactive Cesium From Maccha Green Tea

Some readers were wondering if radioactive cesium had been detected in the type of Japanese green tea in fine powder - maccha (抹茶). So I googled it, and up came the report by Seikatsu Club (co-op), as follows:


Maccha  早春の香 (Shinsei Watarai-cha): total cesium 11 Bq/kg. Tea was made [into maccha form] in April.
Maccha  早春の香 (Shinsei Watarai-cha): total cesium  66 Bq/kg. Tea was made [into maccha form] in March.

Maccha  早春の香 (Shinsei Watarai-cha): total cesium 37 Bq/kg. Tea was made [into maccha form] in April.

There is no information when the tea was picked.

Shinsei Watarai-cha is an organic tea grown in Watarai-cho in Mie Prefecture.

On checking the environmental database by Japan Chemical Analysis Center, I've found that the highest level of radioactive cesium (Cs-137) in green tea in Mie Prefecture was in 1988 at 2.9 becquerels/kg. In the past 10 years, it was either "not detected" or less than 0.1 becquerels/kg.

Watarai-cho is located just southwest of Ise City in Mie. Ise City is famous for the Ise Grand Shrine.

By the way, Mie Prefecture is accepting the disaster debris from Iwate and Miyagi. The governor of Mie signed the agreements with his counterparts in Iwate and Miyagi, despite oppositions from mayors in Mie, including the mayor of Ise City and the mayor of Watarai-cho.

UPDATE: comments from people I follow on Twitter:

Kontan_Bigcat: 7 to 9 becquerels/kg of cesium was detected last year from tea in Mie.

Kouta Kinoshita: it is possible that the number is high relative to the level of contamination in Mie, because the tea was organically grown.


The tea that was made into maccha tea was from Aichi Prefecture, east of Mie Prefecture, even though the company who made the maccha tea is a tea grower and blender in Mie Prefecture.


Anonymous said...

Not related to Macha but i found this interesting..and maddenning..

Cognitive dissonance by Foreigners here , so its not just limited to the Japanese...

arevamirpal::laprimavera said...

turning Japanese...

Anonymous said...

Even more delusion here

I think they are turning Japanese i really think so.... ��

Anonymous said...

Latest test of Tea by

214 bq per kg !

Anonymous said...

I used to love green tea. Gave it up months ago thanks to Japan government mismanagement that allows radioactive product on the market, a government that turns a blind eye to blending contaminated and uncontaminated tea, and a government that punishes source labeling cheats with a slap on the wrist.

Yes Japan, your brand has been destroyed by your government's poor management of the food supply.

ToB said...

I love matcha. This is horrible! I find the blithe complacency regarding three melted down reactors and one open air spent fuel pool in a wrecked building in an earthquake zone to be utterly amazing. Never underestimate the power of denial in the face of true horror.

Anonymous said...

Is Kyoto tea contaminated?
Laprimavera, can you find any info on this please?

Anonymous said...

Kyoto tea most probably is contaminated but not too much, I saw results from Greenpeace i think that even tea in Miyazaki had cesium in it although small amounts.. Tea, Spinach, Mushrooms are cesium magnets

Chibaguy said...

A recent blog by Professor Takeda (he is not an end of the world person) suggest by 2015 Japan will surpass the 5mSv/yr limit. The data he is using is from Mie.

arevamirpal::laprimavera said...

@anon at 5;19AM, as far as the testing by the Kyoto prefectural government goes, radioactive cesium in all produce in Kyoto, including tea, is non-detectable level, using the germanium semiconductor detector. You can download the excel file from the Kyoto gov website:

@Chibaguy, yes I read that, too. I'm still trying to figure out whether that makes sense. Mathematically it doesn't make sense (why linear equation?), but without the raw numbers can't even verify. No info whether the survey meter is calibrated. Pre-Fukushima number for Mie was 0.042 microsievert/hour.

kuma shutsubotsu chuui said...


Many thanks for digging up the information.

I'm not generally a big-green tea drinker, but I do keep matcha in the house and often whip up a bowl of it to relax. I also make matcha milk, matcha ice cream, matcha bread, matcha cookies ... etc. It's good to know that Kyoto tea seems to be okay.

Kyushu matcha seems to be rare, but I found this page for Fukuoka Yame tea (in Japanese):

800-1200 yen for a 20g can. (Eek. I usually buy the cheap stuff.) I don't know anything about cesium content for the above tea.

Anonymous said...

Just heard this Rense interview about Fukushima.... Rense said that EXSKF blogger is a woman... For some reason i thought it was a guy... Wow.


Anonymous said...

Maybe a different perspective about radiation and radioactive contamination should be considered. I have previously expressed my thoughts that radiation studies may be seriously flawed statistically. I am skeptical of both the LNT (Linear No-Threshold) theory and hormesis, as the former seems to assign blame for all excess cancers to radiation, while the latter assumes that fewer than normal cancers are due to the "therapeutic" effects of radiation. Maybe a more balanced approach is that in both cases too much is assumed and that there are confounding variables that may explain most or part of the difference in cancer rates. I am particularly troubled by the standard of 100 Bq/kg, when (normal) coffee has 1000 Bq/kg (

What seems to be missing is the possibility that chemical toxicity of cesium may be more important than the radioactive toxicity. Ordinarily, the level of cesium in air and water is very low: 1 ng/m3 in air and 1 μg/L in water ( Cesium tends to accumulate in the liver, intestine, heart, and kidneys. It can cause ventricular arhythmias and displacement of potassium from muscle and red blood cells, among other health problems ( Patients trying a questionable cancer treatment using cesium chloride have suffered serious side effects (

Is it possible that the biggest risk from environmental contamination by cesium is its chemical toxicity? If so, focus on Bq/kg may be missing the mark. Cesium 137 has a fairly long half-life: 30+ years. By contrast, Iodine 131 has a half-life of 8 days. In general, shorter half-lives are associated with greater activity and iodine 131 is clearly linked with thyroid cancer.

So maybe the combination of (a) very low natural levels of cesium and (b) cesium's tendency to replace potassium may be more important factors in determining the long-term health of people exposed to it than its (perhaps) low radioactivity. So, even if the hormesis theory may have some basis in fact, the chemical toxicity of cesium may be determinant, thus rendering the hormesis theory moot. These is just meant as food for thought, as I don't know how valid it is as there appears to be very little data on environmental contamination by cesium 137 (

Darth3/11--a gal said...

Ex-SKF is a gal? If so, I would have to readjust my mental picture. Also, issue a huge HUZZAH!

Anonymous said...

Anon, in a nano-gram of Cs-137 you already have 3,214 Becquerels and a micro-gram would be 3,214,000 Becquerels. The chemical toxicity of stable cesium is nothing compared to the damage that those kind of activities may cause.

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