Radioactive Leaf Tobacco, 217 Bq/Kg of Cesium – 30 Bq greater than after Chernobyl

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According to the press release by JT, no radioactive cesium was detected in leaf tobacco grown in Shizuoka Prefecture. But of 33 samples in the other 3 prefectures, 27 samples were found with radioactive cesium from the lowest 21 to the highest 217 becquerels/kg (both in Ibaraki).

Cesium-137 concentrations in tobacco leaves in 1986, the year of Chernobyl accident, varied between 70 and 180 Bq kg -1 (average 100 Bq kg -1 ).

From TBS News (9/6/2011):

JT=日本たばこ産業は、これから収穫を迎える「葉たばこ」について放射性物質の検査を行い、「問題ない」とする結果を公表しました。

JT (Japan Tobacco Inc.) announced the result of the survey of leaf tobacco for radioactive materials and said “there is no problem”. The harvest season for leaf tobacco will start soon.

JTは、10月から本格化する葉たばこの収穫を前に、休耕中の福島を除く茨城・栃木・千葉それに静岡の4つの県で、「黄色種」という乾燥済みの葉たばこについて放射性物質の検査を行ないました。

The harvest season for leaf tobacco will start in October in earnest. JT conducted the survey of one type of leaf tobacco, dried, in 4 prefectures (Ibaraki, Tochigi, Chiba, and Shizuoka). Fukushima Prefecture was excluded as no leaf tobacco is grown this year.

それによりますと、すべての検体で放射性ヨウ素は検出限界を下回りましたが、放射性セシウムが最高で1キログラムあたり217ベクレル検出されたということです。

According to the survey, radioactive iodine in all samples was below the detection level. However, the maximum 217 becquerels/kg of radioactive cesium was found.

葉たばこには国による規制値が定められていませんが、JTではこの結果について、野菜などに適応される暫定規制値の1キログラムあたり500ベクレルを下回っているため「問題はない」と説明してます。JTでは、今後ほかの種類の葉たばこについてもサンプリング検査を実施する方針です。

There is no safety limit for the leaf tobacco. However, JT explained the level of radioactive cesium as “not a problem” because it was below the provisional safety limit of 500 becquerels/kg for vegetables. JT is going to conduct a sample monitoring of other types of leaf tobacco.

According to the press release by JT, no radioactive cesium was detected in leaf tobacco grown in Shizuoka Prefecture. But of 33 samples in the other 3 prefectures, 27 samples were found with radioactive cesium from the lowest 21 to the highest 217 becquerels/kg (both in Ibaraki).

After Chernobyl

A study of radioactivity in tobacco leaves collected before cigarette production was conducted in order to find out any association between the root uptake of radionuclides from soil ground by the tobacco plants and the effective dose induced to smokers from cigarette tobacco.

The cesium radioisotopes 137 Cs and 134 Cs in tobacco leaves were due to root uptake and not due to deposition onto the leaf foliage as they still remained in soil four years after the Chernobyl reactor accident, but were absent from the atmosphere because of the rain washout (precipitation) and gravitational settling.

The annual effective dose from 137 Cs of Chernobyl origin was three orders of magnitude lower as it varied from 70.4 to 410.4 nSv/y (average 199.3 nSv/y).

Cesium-137 activity concentrations in the tobacco leaves ranged from 1.20 to 7.00 Bq kg -1 (average 3.40 Bq kg -1 ).

The results showed that 137 Cs concentrations were due to root uptake because 137 Cs (T1/2=30.17 y) still remained in soil four years after the Chernobyl reactor accident.

Cesium-137 concentrations in tobacco leaves in 1986, the year of Chernobyl accident, varied between 70 and 180 Bq kg -1 (average 100 Bq kg -1 ).

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