Japan announced the first signs that contamination from its tsunami-crippled nuclear complex has seeped into the food chain, saying that radiation levels in spinach and milk from farms near the facility exceeded government safety limits.
Japanese officials insisted that the small amounts of radiation — with traces also found in tap water in Tokyo — posed no immediate health threat, and said the situation at the Fukushima Dai-ichi plant, while still unpredictable, appeared to be coming under control after near-constant dousing of water to prevent spent fuel rods from burning up.
Emergency teams using an unmanned vehicle to spray water targeting the most at-risk of the plant's six reactors launched a new round Sunday — aimed at the plant's Unit 4 — while preparing to switch power back on for the first time since a March 11 earthquake and tsunami knocked out the plant's crucial cooling systems.
However, there was no guarantee the cooling systems would still work, even once power was restored.
Japan has been struggling with an overwhelming chain of disasters prompted by the 9.0-magnitude quake. The quake spawned a tsunami that ravaged Japan's northeastern coast, killing more than 7,700 people and knocking out cooling systems at the plant, prompting overheated reactors and fuel to leak radiation.
More than 11,600 people are still missing, and more than 452,000 are living in shelters.
The government's top spokesman, Chief Cabinet Secretary Yukio Edano, said at a news conference Saturday that tainted milk and spinach were collected from several farms ranging from 20 miles (30 kilometers) to 75 miles (120 kilometers) away from the reactors.
After the announcements, Japanese officials immediately tried to calm an already-jittery public, saying the amounts detected were so small that people would have to consume unimaginable amounts to endanger their health.
"Can you imagine eating one kilogram of spinach every day for one year?" said State Secretary of Health Minister Yoko Komiyama. One kilogram is a little over two pounds.
Edano said someone drinking the tainted milk for one year would consume as much radiation as in a CT scan; for the spinach, it would be one-fifth of a CT scan. A CT scan is a compressed series of X-rays used for medical tests.
Minuscule amounts of radioactive iodine also were found in tap water Friday in Tokyo and elsewhere in Japan — although experts said none of those tests showed any health risks. The Health Ministry also said that radioactive iodine slightly above government safety limits was found in drinking water at one point Thursday in a sampling from Fukushima prefecture, the site of the nuclear plant, but later tests showed the level had fallen again.
Six workers trying to bring the Fukushima Dai-ichi plant back under control were exposed to more than 100 millisieverts of radiation — Japan's normal limit for those involved in emergency operations, according to Tokyo Electric Power Co., which operates the complex. The government raised that limit to 250 millisieverts on Tuesday as the crisis escalated.
An expert in the United States also said the risk from the radiation levels in food appeared limited and urged calm.
"The most troubling thing to me is the fear that's out of proportion to the risk," said Dr. Henry Duval Royal, a radiologist at Washington University Medical School.
The areas where the spinach and milk were sampled are rich farm country also known for melons, rice and peaches, so the contamination could affect food supplies for large parts of Japan.
More tests were being done on other foods, Edano said, and if they show further contamination, then food shipments from the area would be halted.
Iodine levels in the spinach exceeded safety limits by three to seven times, a food safety official said. Tests on the milk done Wednesday detected small amounts of iodine-131 and cesium-137. High levels of iodine are linked to thyroid cancer, one of the least deadly cancers if treated. Cesium is a longer-lasting element that affects the whole body and raises cancer risk. But only iodine was detected Thursday and Friday, a Health Ministry official said.
The Health Ministry said iodine levels slightly above the safety limit were discovered Thursday in drinking water samples from Fukushima prefecture. On Friday, levels were about half that benchmark; by Saturday, they had fallen further.
Drinking one liter of water with the iodine at Thursday's levels is the equivalent of receiving one-eighty-eighth of the radiation from a chest X-ray, said Kazuma Yokota, a spokesman for the prefecture's disaster response headquarters.
At the Fukushima plant, some 500 workers have been thrown in to the effort to keep the nuclear fuel cool and reconnect the plant to the power grid. The safety threshold for their radiation exposure was raised 2 1/2 times so they could keep working.
Officials insisted that would cause no health damage.
Edano said conditions at the reactors in Units 1, 2 and 3 — all of which have been rocked by explosions in the past eight days — had "stabilized."
The reactors and the storage pools both need constant sources of cooling water. Even when they are taken from reactors, uranium rods remain very hot and must be cooled for months, possibly longer, to prevent them from heating up again and emitting large amounts of radioactivity.
Low levels of radiation have been detected well beyond Tokyo, which is 140 miles (220 kilometers) south of the plant, but hazardous levels have been limited to the plant itself.
People evacuated from around the plant, along with some emergency workers, have tested positive for radiation exposure. Three firefighters needed to be decontaminated with showers, while among the 18 plant workers who tested positive, one absorbed about one-tenth of the amount that could induce radiation poisoning.
Outside the bustling disaster response center in the city of Fukushima, 40 miles (60 kilometers) northwest of the plant, government nuclear specialist Kazuya Konno was able to take only a three-minute break for his first meeting since the quake with his wife, Junko, and their children.
"It's very nerve-racking. We really don't know what is going to become of our city," said Junko Konno, 35. "Like most other people, we have been staying indoors unless we have to go out."
She brought her husband a small backpack with a change of clothes and snacks. The girls — aged 4 and 6 and wearing pink surgical masks decorated with Mickey Mouse — gave their father hugs.
The government conceded Friday that it was slow to respond to the crisis and welcomed ever-growing help from the U.S. in hopes of preventing a complete meltdown.
Japanese nuclear safety officials have said the plant's backup power systems may have been improperly protected, leaving them vulnerable to the tsunami.
The crisis has led to power shortages and factory closures, and triggered a plunge in Japanese stock prices.
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