Cesium in Baby Milk Powder Shows Lingering Threat of Radiation in Japan
Meiji the past week found traces of cesium-137 and cesium- 134 in batches of “Meiji Step” made in March, the Tokyo-based company said yesterday. The probe was triggered by a customer complaint last month. Levels in the 850-gram (30-ounce) cans are within safe limits and don’t pose a health risk, Meiji said.
The finding highlights the radiation threat to food in Japan nine months after the Fukushima nuclear plant was wrecked by an earthquake and tsunami. Prolonged exposure to radiation in the air, ground and food can damage DNA, causing leukemia and other cancers. While infants are especially susceptible, the contamination may not be a significant threat if limited to small quantities in isolated batches, said Slim Dinsdale, a food safety consultant based in Norwich, England.
“If it’s just a one-off, ‘safe’ dose then it may well be of a similar level to the background levels” residents are routinely exposed to, Dinsdale said in a telephone interview. “I’d want to avoid cesium if I knew it was there, whether it was a safe dose or not.”
Nomura Holdings Inc. cut its rating (2269) on Meiji to “neutral” from “buy,” citing consumer perceptions about the safety of the company’s products.
“The impact to earnings isn’t expected to be so large,” Keiko Yamaguchi, a consumer-products analyst at Nomura in Tokyo, said in a report yesterday. Any rumors about product quality may dent sales of other Meiji products, she said.
Tests conducted on Dec. 3 and 4 found Cesium-134 at levels as high as 15.2 becquerels per kilogram, while cesium-137 reached 16.5 Bq/kg, according to Meiji. A becquerel is a measure of radioactivity. The maximum permissible level for milk and dairy products for infants is 200 Bq/kg, the company said.
As a result of the tests, the company said it’s recalling 400,000 cans of “Meiji Step,” a powdered milk formulated for babies older than nine months, packaged in April and mostly distributed in May. The affected cans expire in October 2012.
“The dose is pretty small,” said Richard Wakeford, a visiting professor in epidemiology at the University of Manchester’s Dalton Nuclear Institute. It wouldn’t be necessary to ban the products from a radiological protection point of view, he said. “But you can understand the kind of pressure that the manufacturer would be under in these circumstances.”
Meiji rose 5.1 percent to 3,175 yen at the 3 p.m. close on the Tokyo Stock Exchange, rebounding from a 9.7 percent decline yesterday to a 30-month low. Rival Morinaga Milk Industry Co. jumped 3.6 percent to 285 yen and Megmilk Snow Brand Co. advanced 4.6 percent to 1,475 yen.
Nine-month-old babies would typically consume from 400 milliliters (14 ounces) to 700 milliliters of milk, including 56 grams to 98 grams of powder, Japan’s National Institute of Radiological Science said in an e-mailed response to questions. Daily consumption of the contaminated product could yield about 0.07 microsievert of radiation for a 9-month-old baby and 0.03 microsievert for a 1-year-old toddler, it said.
The majority of other Meiji milk products produced around the time that the contaminated items were made weren’t found to have cesium levels above 5 becquerels per kilogram, the institute said.
The products were made at a factory in Saitama prefecture, about 200 kilometers southwest of the Fukushima plant, between March 14 and March 20, the company said. The raw milk had been produced before the March 11 disaster and water used in the production process wasn’t found to be contaminated, Meiji said.
The monitoring didn’t detect radioactive materials in Meiji’s “Hohoemi” brand, the company said. Retailers Seven & I Holdings Co. and Aeon Co. said they are offering to replace the recalled products.
Radioactive barium, cesium, iodine and tellurium were detected March 16 in a radiation plume released by damaged nuclear reactors at Fukushima. A partly dispersed cloud passed by the Tokyo area the same day, Austria’s Meteorological and Geophysics Center reported.
The presence of cesium at the levels found indicates contamination from nuclear fission products, possibly as a result of explosions at Tokyo Electric Power Co. (9501)’s Fukushima plant, said Stephen Lincoln, a professor of chemistry at the University of Adelaide in South Australia.
“There is only one source of cesium in that milk: nuclear fission from a nuclear reactor or spent fuel,” Lincoln said in an interview yesterday. “There may be parts around Fukushima that will have to be evacuated for 100 years. There is no way you can make radioactive decay happen more swiftly.”
In and Out
In a nuclear accident, radioactive isotopes including iodine-131 and cesium-137, which are normally contained inside the fuel rods, may be released into the atmosphere as gases or particulates if the rods are damaged. These can be inhaled or ingested through contaminated food or water. Children are especially susceptible to radiation poisoning from iodine, which can accumulate in the thyroid gland, according to the World Health Organization.
Cesium-137 that enters the body is distributed throughout the soft tissues, especially in muscle. Cesium-137 is eliminated faster from the body than other radionuclides, according to the U.S. Environmental Protection Agency.
“Slowly, but surely it will pass out of the body,” said Lincoln.
Radiation is more dangerous for infants because their cells are dividing more rapidly and radiation-damaged RNA may be carried in more generations of cells, according to Lincoln.
The risk for children depends on the quantity of radioactive cesium they consume or are exposed to, he said. If contaminated milk powder is consumed for only a few days, most of it will likely be eliminated within a month, he said.
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