March 21 (Bloomberg) -- Japan’s Ministry of Health, Labor and Welfare has set safe limits for radiation in various products for human consumption.
Authorities have heightened monitoring for contamination following the emission of radioactive material from Tokyo Electric Power Co.’s Fukushima Dai-Ichi nuclear power plant since the March 11 earthquake and tsunami. Radiation in food is measured in Becquerel, a gauge of the strength of radioactivity in materials such as Iodine-131 and Cesium-137.
The prescribed safe limit for I-131 in vegetables is set at 2,000 Becquerel (Bq) per kilogram and 500 Bq/kg for radioactive cesium.
The highest reading reported on the health ministry’s website so far has come from a sample of spinach collected on March 18 from Hitachi city, 97 kilometers (60 miles) south of the plant. The spinach, which didn’t enter the food chain, contained 27 times the safe limit of radiation for I-131, according to the health ministry.
The spinach contained 54,100 Bq/kg of I-131 and 1,931 Bq/kg of cesium. That means consuming 1 kilogram (2.2 pounds) of fresh spinach would yield a radiation exposure of 1.2 millisieverts, or half the average annual natural exposure from soil and cosmic rays, based on Bloomberg calculations using a formula posted on the website of Japan’s Food Safety Commission.
Japan’s health ministry advises that materials exceeding 100 Becquerel per kilogram shouldn’t be used as the basis for powered infant milk formula.
================================================================ Prescribed safe limits for radioactive Iodine-131: ================================================================ 300 Becquerel per kilogram Drinking water 300 (Bq/kg) Milk, dairy products 2,000 (Bq/kg) Vegetables* (*Except root vegetables and tubers) ================================================================ ================================================================ Prescribed safe limits for radioactive cesium: ================================================================ 200 Becquerel per kilogram Drinking water 200 (Bq/kg) Milk, dairy products 500 (Bq/kg) Vegetables 500 (Bq/kg) Grains 500 (Bq/kg) Meat, eggs, fish, etc. ================================================================ Prescribed safe limits for uranium: ================================================================ 20 Becquerel per kilogram Infant foods 20 (Bq/kg) Drinking water 20 (Bq/kg) Milk, dairy products 100 (Bq/kg) Vegetables 100 (Bq/kg) Grains 100 (Bq/kg) Meat, eggs, fish, etc. ================================================================ ================================================================ Prescribed safe limits for alpha-emitting nuclides of plutonium and transuranic elements: ================================================================ 1 Becquerel per kilogram Infant foods 1 (Bq/kg) Drinking water 1 (Bq/kg) Milk, dairy products 10 (Bq/kg) Vegetables 10 (Bq/kg) Grains 10 (Bq/kg) Meat, eggs, fish etc. ================================================================
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