In March 2011, the famous and unfortunate nuclear disaster took place in Fukushima. Since that day, possible green tea contamination with radiation has been a real concern for green tea lovers around the world.
Before we talk about this further, the short answer to the question in the title is: "As of now, No." We are not aware of any Matcha type in the US market being contaminated with radiation.
Having said that, it is a fact that traces of radioactive contamination were detected in green tea a number of occasions. In 2011, and according to the New York Post, dried leaves from the year’s first harvest in the Honyama area of Shizuoka were found to contain radioactive cesium above the maximum permitted level. In 2015, and according to the New York Times, traces of radioactive cesium (described as below legal maximum level) were detected in green tea shipped from Japan to Hong Kong, and that tea was imported from prefecture of Chiba.
The map above highlights the most popular green tea producing regions. The red symbol in the right upper corner refers to the area were the 2011 nuclear disaster took place. The two regions where green tea produce was once found to have traces of radiation contamination are underlined with a red color. The vast majority of Matcha Powder in the market originates from Aichi (Nishio) and Kyoto (Uji).
When it comes to radiation contamination, I am not licensed to give any professional advice, and the following is simply a personal opinion. It is known that radiation contamination may spread with water and wind currents. Given the pattern of spread, I believe it is safe to assume that the farther the tea growth is from Fukushima, the less likely it has been contaminated. (Taken into account other factors as well, such as direction of wind and water currents.)
If you are a regular Matcha drinker, keeping in mind that possible radiation risk is completely understandable. Speaking of myself, I drink Matcha at least 2-3 times a day, I use Matcha as an ingredients in foods and desserts, and I also have two young daughters that I allow minimal amounts of Matcha in smoothies that they go crazy for; however, and although I find the mood, energy, and health benefits of Matcha irresistible, I do not take the possibility of radiation contamination lightly.
While this is by no means a claim that our Matcha is "safer", the physical location of Yame and Uji in relation to Fukushima is undeniably a factor we have considered before deciding on which Matcha we will be serving our customer and use personally. On top of that, we also obtain certified analysis reports regularly to prove undetectable levels of contamination. That being said, as all Matcha enthusiasts, I occasionally enjoy other types of Matcha from time to time as there are equivalently high-end Matcha from various regions in Japan.
Finally, if you are interested in learning more, and would like to closely follow up on this matter, we highly recommend following Japan’s Ministry of Health that post updates weekly with testing results for levels of radioactive contaminants in tea and other produce.