Japan Officials Debate Whether Contaminated Tea is Dangerous



No contaminated tea is shipping from Japan but agricultural and commerce ministers now question the current radioactivity threshold.

Authorities halted the ichibancha (first flush) harvest in the vicinity of Minamiashigara last week after tests at five municipalities in Kanagawa Prefecture showed cesium readings greater than 500 Bq/kg (becquerels per kilogram). Additional tests this week are expected to show readings from 200 to 900 Bq/kg in gardens northeast of Shizuoka towards Tokyo and in the northern most gardens in the vicinity of Fukushima.  Vegetables and other food crops that test above the 500 Bq/kg limit for cesium may not be legally sold or shipped according to the Health, Labor and Welfare Ministry. Officials in the Agriculture, Forestry and Fisheries Ministry say the voluntary ban is unnecessary.

"The 500-becquerel limit is too strict. Even though tea leaves aren't supposed to be eaten raw, they're subject to the same limit as vegetables," an unnamed ministry official told reporters from the Yomiuri Shimbun newspaper. "We don't have rules on what stage of processing should be restricted. So restricting shipments under these circumstances would only create confusion."

The debate boils down to whether high readings in fresh leaves will lead to harmful levels in the drink itself. Drying four pounds of fresh leaves to produce one pound of dried leaves concentrates the radioactive material between four and five times. Dried leaves (ara cha) tested in Minamiashigara were found to contain 3000 Bq/kg of cesium. However many of these radioactive particles are never ingested as they remain in the leaves after steeping.

Japan’s radiation limits are set below the 1000 Bq/kg threshold for cesium listed in the Food and Agricultural Organization and World Health Organization’s Codex Alimentarius. The food safety guidelines were updated May 2 for nuclear emergencies.

The international safety standard for radioactive cesium in water is 200 Bq/l (5 milisieverts). Agriculture ministry officials maintain that radioactive materials are diluted between 1-to-30 and 1-to-45 using minimally processed leaves and by one-sixth to one-ninth in tea made from fresh leaves. Tea drinkers typically use 4 grams to make 160 militers of tea. "Early data in cup suggests less than 10 percent is getting into the tea, but that is a hypothesis, not necessarily a like-for-like analysis," advises Dr. Andrew Scott. He notes that it is common practice in Asia to drink tea leaves brewed more than once."

Virtually all the region’s tea, collectively known as Ashigara, is consumed domestically. As a precaution the prefecture halted all shipments of tea leaves within its boundaries. Private sector and public testing has been ongoing across Japan since the discovery of radioactive iodine and cesium in vegetables but this is the first instance where tea has been contaminated.

The Ashigara region is southwest of Tokyo and 280 kilometers from Fukushima, the site of four badly damaged nuclear reactors that continue to spew radionuclides and are likely to do so for several months. The discovery of Cesium-137 on May 9 has been traced to the earlier explosion at the Fukushima-Diiachi powerplant. The Minamiashigara area gardens tested 570 Bq/kg with subsequent tea readings of 780 Bq/kg reported in tea leaves sampled in Odawara and 740 Bq/kg in Kiyokawa tea leaves. Samples from Yugawa gardens were tested at 680 Bq/kg. Kanagawa officials say the gardens will be tested again next month just prior to the nibancha harvest. Until then the harvest of green tea is suspended.

No tea in the prefectures further south have exceeded the 500 Bq/kg.

In a similar situation following the 1986 explosion and meltdown of the Chernobyl reactors in the Soviet Union, samples from tea gardens in Turkey and Georgia tested at 25,000 Bq/kg to 89,000 Bq/kg. Cay-Kur, Turkey’s national tea company, buried 58,000 tons of the most badly contaminated teas and simply blended the remainder with the previous year's crop to arrive at an average 12,500 Bq/kg reading. At that time less was known about the hazards of food borne radionuclides. Subsequent experiments showed that 60 percent of the radiation was transferred to the liquor from contaminated leaves.

The concern among Japanese tea professionals is over reaction. Kotaro Tanimoto, President of the Tea Import/Export Association prepared the attached report primarily for the European market. It provides a general overview useful when explaining the situation to customers that are predictably alarmed. Click here to view the presentation from the Japan Tea Exporter’s Association.

On learning of the contamination retailer Steven Sartini at La Teiera Eclettica in Milan, Italy expressed frustration that “I now have no arguments to use when the ever increasing numbers of customers declare they will stop consuming any tea from Japan. Some have even stated concern for Chinese teas that, as far as they're concerned (due to total ignorance of geography), is close enough to Japan for radioactive contamination...”

Individuals familiar with Japan have been working with World Tea News to update readers. Two weeks ago our correspondents visited Shizuoka Prefecture, the most productive of Japan's tea growing regions. Approxmiately 60 percent of the nation's 96,0000 tons are grown or processed in this central region. This is also where  the majority of tea is exported from the Port at Yokohama. Click here to read that installment. This week we visit Kagoshima, the southern most tea growing region and the northern most region of Saitama and Iberaki Prefecture which are closest to the stricken reactor.


Kagoshima is hundreds of kilometers from the fallout zone. The harvest is lightly impacted. Nozomu “Nez” Tokugawa, a tea importer/wholesaler and owner of the Chado-En tea house near San Francisco, traveled to Kagoshima last week. Here is his report:

“No problems have been detected at any level. I met with several farmers, processors and spent time at the tea market. We had a meeting with Mr. Motoyama the Prefectural Officer and Agronomist of Green Tea as well as Mr. Oki the manager of the tea market. I was able to ask detailed questions and received very satisfactory answers,” says Tokugawa.

“Unlike Shizuoka farmers of which only about 30 percent go to the market with their tea – 70 percent of Kagoshima farmers sell at the market,” says Tokugawa.

He describes the market as “very modern, computerized and has complete traceability of the entire chain. A number of factories have software where they are able to send directly to the market daily activities such as fertilizer, cleaning of factory, pesticides used even by date and time etc.”

“Annually there are audits to ensure this data is correct. The prefecture is very forward thinking and even subsidizes farmer’s purchase of machines that can detect any foreign material in the leaf,” says Tokugawa.

“I am very impressed overall and pleased to see the conditions in Kagoshima are very safe and controlled. When I asked each of the people we met “how would you like Kagoshima tea to be known outside of Kagoshima? the reply was consistent – Clean, Safe and Traceable followed by a phrase that translates as ‘bigger energy and much vigor.’ Indeed I felt this in Kagoshima,” he writes.


The U.S. Food & Drug Administration (FDA), along with its counterpart in Japan, has halted all exports from Fukushima/Sendai region.

The 15,000 residents of Minamisoma and Kawamata and nearby villages in Fukushima Prefecture abandoned their homes this week due to high levels of radiation. The villages are outside the 20 km mandatory evacuation zone but experienced frequent periods of high readings. Government officials recommended the relocation. The crisis has displaced 80,000 individuals most of whom were ordered from their homes. Many expect to return once the nuclear reactors are sealed and shut down, but that will likely take another six months at best.


Takanori Fujita, assistant manager of forestry department in Daigo-machi says testing of tea gardens will be done by the Okukuji Tea Association, not by Ibaraki Prefecture or Daigo-machi. Fujita says test results from vegetables make it unlikely there will be problems with tea. Initial concern was over contamination by Iodine-131 which has a short half life. These gardens are distance from Daigo-machi where contaminated spinach was found. The Fukushima nuclear plant is about 100 km away and there are many mountains between them, he says.

Michihiko Sato who works at Ibaraki Prefectural Environmental Radiation Monitoring Center says the center is currently conducting testing for water, vegetables and seafood but not tea. Sato expects the testing program to expand. Test results are posted on Ibaraki Prefecture’s website.

Diligent Manufacturers

Garden owners and manufacturers are the first line of defense.

Hundreds of Geiger counters and trained inspectors are deployed in a public/private partnership that extends from the fields to the ships in port.

“We are monitoring for radioactive material/measurements every eight hours,” says Rona Tison, ITO EN Inc. (North America) Sr. Vice President-Corporate Relations. The firm analyzed this April's new crops of green tea used to make both our leaf products and bottled tea products. “No radiation has been detected and all tea from our partner farms is completely safe for consumption,” says Tison. “No ITO EN products come from the affected region,” she says. “All tea fields and production facilities are a safe distance to the Southwest,” she says.

Ready-to-drink bottled teas are tested after every production run. Products are released “only if no sign of radiation is present,” says Tison. “In the unlikely event that our Geiger counters detect radiation, affected products will not leave Japan and will be discarded in accordance with the greatest of care,” she says.

ITO EN conducts daily monitoring for radioactive material/measurements around co-packing plants within 200 miles of the Tohoku and Kanto regions, she said. In addition to finished products, the firm is collecting water samples (ground water, system water and pure water) from 46 co-packers in Japan at the end of March. No radioactive material was detected by our Geiger counters from any of the water sources inspected, says Tison.

Monitoring the Situation

Several very useful websites are updated frequently regarding the situation in Japan. Real time radiological monitoring is available from the Ministry of Education, Culture, Sports, Science and Technology (MEXT).

Click here to download readings of radioactivity in Japan.

Click here to download readings of radioactivity by prefecture.

Click here for a interactive map that indicates the level of radioactivity in Japan's 47 prefectures.

The International Atomic Energy Agency provides daily briefings on the situation in Japan. The IAEA's Fukushima Nuclear Accident Update Log closely follows progress as the Japanese strive to contain radiation leaking from the stricken power facility.

The United States Department of Energy maintains a helpful blog called "The Situation in Japan" that is updated frequently. The department also produced a very informative slide presentation that you can download here.

The World Health Organization issued this guidance on food safety useful to tea retailers, importers of Japanese tea and wholesalers answering questions from their clients and the public.

Dan Bolton