I hope this helps. On Facebook, Kyoto Journal is having a good discussion on Shizuoka tea.So, I investigated related sites, and the following site, I found most of information including tea: http://atmc.jp/
You can compare with the US standards which are in rightmost columns.
Related to tea, I found the following three sites.
1. fresh tea leaf (we do not consume fresh leaf.)
2. dried tea leaves (we do not eat.)
3. tea drink (this is relevant.)
About high or low radiation, it is relative. On this subject, please read my blog, "High or Low."
I don't work for the tea industry nor the Japanese government.