Since 2011 we have been testing all four types of our tea (matcha, gyokuro, sencha, and bancha) for radiation through a 3rd-party-organization (Japan Food Inspection Corporation). Specifically, we test for Iodine-131, Cesium-134, and Cesium-137, following Japanese government recommendations for which radioactive substances to test for in food items.
The frequency of the examination is once per year, and our teas our harvested only once per year.
Since we have started the examination, none of the tested radioactive substances have been detected.
After almost a decade of doing the examination and confirming that our teas are safe, in 2019 we began to test one type of tea, chosen randomly, to examine each year. The tea plantations that produce our tea are in a limited area, and have not changed over the years.
The most recent test, of the 2020 harvest, detected no radioactive substances.