Tests in five of the first 20 Shizuoka tea processing facilities to be tested showed illegal concentration of cesium in dry tea leaves. All were promptly shut down and recent shipments recalled.
Levels varied from 581 to 654 bequerels per kilogram (bq/kg) in a quarter of factories tested in the Warashina district, which contains 100 factories. Japan's legal limit is 500 bq/kg. Testing continues today. The mayor of Shizuoka told reporters the city will seek compensation from the government for damages.
Shizuoka Prefecture Gov. Heita Kawakatsu had previously declared tea in all 19 wards to be free of illegal concentations, an announcement that led factories to operate without worry. Japan's harvest is fully underway with tons of tea leaves destined for Shizuoka's factories.
The discovery by a Tokyo mail order house last week that tea from Shizuoka contained 679 bq/kg of Cesium-134 and Cesium-137 prompted the government to order tests of a hundred tea processing factories in Shizuoka City. The tea, marketed under the Honyama brand was recalled. Two thirds of the tea processed in Shizuoka Ctyis marketed as Honyama.
The contaminated tea was plucked in the Aoi and Suruga wards of Shizoka city. It was delivered as unrefined "aracha" then sorted, steamed and dried to become "seicha" the Japanese word for refined tea.
The area immediately surrounding Shizuoka City harvested 3,240 tons of unrefined, dried leaves last year according to agricultural officials. The prefecture produced 35,000 tons of dried leaves. In addition, Shizuoka factories also refine 70 percent of the tea grown in Kagoshima prefecture
Shipments were halted and a recall ordered by Japan's Ministry of Health, Labour and Welfare on June 9 when tea was found have exceeded cesium levels despite government safety assurances.
Governor Heita Kawakatsu issued a safety declaration on May 18 assuring the public that tea leaves grown in all 19 of the prefecturre's wards did not exceed the legal threshold of 500 becquerel/kilogram (bq/kg). A senior official with the prefecture's Economy and IndustryDivision acknowledged the day after the discovery of tainted tea that "we may have resiults like this at particular locations" but assured members of the press that Shizuoka tea is safe.
Yoshio Masui, president of the Shizuoka Cha Ichiba (Shizuoka tea market) told the newspaper Asahi Shimbun that "To regain consumer confidence, I just wish that harmful rumors wouldn't spread further."
Masanori Den Shirakata owner of Den's Tea, who is in Shizuoka, says the contaminated tea was produced in a factory in the Warashina district in Shizuoka City.
"Japanese government officials have asked 100 tea processing plants in the district not to ship any tea and also requested wholesalers refrain from distributing the teas locally. Officials of the prefecture are now testing to determine whether the contamination occured in the district, in a particular growing region or just that factory," he says.
Early in June the ministry greatly expanded restrictions on tea, adding portions of three northern prefectures to the leaf ban following additional testing. Tea grown in portions of five prefectures is now restricted.
The high reading was discovered by a mail order tea company in Tokoyo that carried out its own measurements, suggesting that contaminated teas may already have reached the market. The firm quickly began a recall. The level of contamination was low enough that the U.S. Food an Drug Administration would have passed the tea at the US border as it has set an Intervention Level of 1200 bq/kg becquerels per kilogram for cesium. Japan imposes more restrictive limit of 500 bq/kg.
Previously the prefecture reported safe levels in all regions. Dried leaves discovered by the Tokyo mail house had readings of 679 bq/kg of cesium.
Neither fresh or processed tea can be shipped from the Aoi and Sunuga wards and the ban extends to all of Ibaraki prefecture as well as tea from six towns in Chiba Prefecture, two in Fukushima Prefecture and six towns in Kanagawa Prefecture.
Northern Japan produces relatively little green tea and almost all is consumed locally. However Shizuoka is a major production region accounting for 39.3% percent of Japan's annual production of 95,000 tons. Much of the nation's tea exports originate in Shizuoka where picturesque gardens are framed byimages of Mt. Fuji.
In addition, much of the tea grown in surrounding areas is processed in Shizuoka factories after which it can be marketed as Shizuoka tea. The tea is then shipped through the port at Yokohama.
"Many farmers sell to either Shizuoka or Kyoto to be able to better market and sell using these popular names," says Nez Tokugawa, a respected importer who owns Chado-En.
He recently returned from Japan.
"It is important that we make it understood that there are many regions in Japan beyond Shizuoka so it is very possible for people to continue to receive the quality tea. Although bad news for Shizuoka, not so bad for Japan overall. Diversity is a good thing," he says.
"I have traveled to many of the regions and I can tell you first hand, the quality and wonderful unique teas is nothing short of amazing," says Tokugawa.
With the marketability of so much tea in question, shortfalls are projected and the price of green tea is rising. Unexpected demand within Japan means stocks from last year available for export are nearly depleted. Local shortages are anticipated and the bans may encourage customers to shift from green tea to cheaper alternatives such as oolong, according to the agricultural ministry's press office.
The newspaper reports that "since the announcement that inspections would take place, many customers have returned or are not buying first-harvest tea. Quite a few consumers have called markets concerned about this year's tea and have inquired about any remaining stock from last year."
"I hear the prices of tea leaves from outside Shizuoka Prefecture are on the rise," tea market president Masui said. "I want there to be standards with scientific grounds (assuring tea safety)."
Japan's harvest was valued at $1.3 billion in 2009. All prefectures where tea is grown have been asked to test leaf and dried tea where possible but a shortage of equipment and personnel leaves the task to growers and processors.
The contaminated tea was harvested 360 kilometers (225 miles) from Fukushima. Emissions from three partially melted reactor cores are now estimated at double the initial assessment, according to the Nuclear and Industrial Safety Agency, Japan’s nuclear regulatory agency. The pressure vessel at one of the plant’s reactors was compromised as soon as five hours after the quake, the agency told reporters.
The release of radioactive iodine and cesium peaked between March 14 and 16 following the March 11 quake and tsunami. It is now evident there were meltdowns in three reactors and that an estimated 770,000 terabecquerels of radioactive particles were released. A terabecquerel is a trillion becquerels, a measure of radiation. The release is between 20 and 40 percent of the 1986 fallout from Chernobyl, the world's worst nuclear disaster.
In fresh vegetables and leaves a residue of 500 bq/kg of cesium is Japan’s legal limit for transport and consumption. Yasuo Sasaki, senior press counselor at the Ministry of Agriculture, Forestry and Fisheries said radiation in tea leaves containing even small amounts of cesium is concentrated by four or five times in the tea making process and can reach levels well above the 1000 Bq/kg considered safe by international standards.
Green tea leaves tested in Kanagawa prefecture in Mayexceeded Japan's legal limit. Authorities halted the ichibancha (first flush) harvest in the vicinity of Minamiashigara after tests at five municipalities in Kanagawa prefecture showed cesium readings greater than 500 Bq/kg. Additional tests showed 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 220 kilometres (135 miles) northeast of Tokyo and 280 kilometres from Minamiashigara.
The central government previously imposed a ban on a range of vegetables and dairy produce from parts of Fukushima prefecture and several neighbouring regions, and banned fishing in the vicinity of the plant. The ban was recently expanded to include plums.
Beverage concentrations unknown
An unknown factor is 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 isotopes. Cesium-137 has a half-life of 30 years and Cesium-134 is radioactive for two years. However many of these radioactive particles are never ingested as they remain in the leaves after steeping.
Agricultural ministryofficials estimate tea brewed from contaminated leaves contains between 30 and 45 times less cesium but one official claimed dilution was 85 times. (Measures are based on 60 grams of green tea, brewed 60 seconds, in 2580 ml of 90-degree C water).
The amount of radioactive material that is injested depends on many variables which makes customers uneasy. 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 (PDF download). 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, a British tea expert. He notes that it is common practice in Asia to drink tea leaves brewed more than once."
Virtually all the Kanagawa 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 borders Shizuoka. In May 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. In late May tests near Izu city revealed tea with 98 bq/kg of cesium. The tea was banned June 2.
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 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…”
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