Wednesday, March 23, 2011

Perigo de água contaminada por radiação em Tokyo

Tokyo Says Radiation in Water Puts Infants at Risk

TOKYO — Radioactive iodine detected in Tokyo’s water supply prompted Japanese authorities on Wednesday to warn that infants in Tokyo and surrounding areas should not drink tap water, adding to the growing anxiety about public safety posed by Japan’s unfolding nuclear crisis.

Ko Sasaki for The New York Times

Kokona, an 8-month-old baby, received a medical examination at a temporary clinic in Hadenya, Minamisanroku, Japan. More Photos »

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    Ei Yoshida, head of water purification for the Tokyo water department, said at a televised news conference thatiodine 131 had been detected in water samples at a level of 210 becquerels per liter, about a quart. The recommended limit for infants is 100 becquerels per liter. For adults, the recommended limit is 300 becquerels. (The measurement unit is named for Henri Becquerel, one of the discoverers of radioactivity.)

    The announcement prompted a run on bottled water at stores in Tokyo and a pledge from the authorities to distribute bottled water to families with infants. Prime Minister Naoto Kan said earlier Wednesday that the public should avoid additional farm produce from areas near the Fukushima Daiichi Nuclear Power Station, severely damaged by the March 11 earthquake and tsunami, according to the Japanese news media.

    The Health Ministry said in a statement that it was unlikely that there would be negative consequences to infants who did drink the water, but that it should be avoided if possible and not be used to make infant formula. There was some confusion about the public health advice, with experts saying it should also apply to pregnant women, since they and fetuses are vulnerable.

    “It’s unfortunate, but the radiation is clearly being carried on the air from the Fukushima plant,” said Yukio Edano, the chief cabinet secretary. “Because it’s raining, it’s possible that a lot of places will be affected. Even if people consume the water a few times, there should be no long-term ill effects.”

    There has been frequent rain in recent days and the watershed for Tokyo’s tap water lies almost entirely to the north and northeast of the city. The nuclear plant is about 140 miles to the north.

    But it was not entirely clear why the levels of iodine were so high, said a senior Western nuclear executive, noting that the prevailing breezes seem to be pushing radiation out to sea. “The contamination levels are well beyond what you’d expect from what is in the public domain,” said the executive, who insisted on anonymity and has broad contacts in Japan.

    The daily Asahi Shimbun cited the Health Ministry as saying that drinking the water would hurt neither a pregnant woman nor her fetus, and that it was safe for bathing and other everyday activities.

    But experts say that pregnant women, nursing mothersand fetuses, as well as children, face the greatest danger from radioactive iodine, which is taken in by the thyroid gland and can cause thyroid cancer. Children are at much higher risk than adults because they are growing, and their thyroid glands are more active and in need of iodine. In addition, the gland is smaller in children than in adults, so there is less tissue to share the radiation: a given amount of iodine 131 will deliver a higher dose of radiation to a child’s thyroid and potentially do more harm.

    According to the United States Centers for Disease Control and Prevention, if an adult and a child ingest the same amount of radioactive iodine the thyroid dose will be 16 times higher to a newborn than to an adult; for a child under 1 year old, eight times the adult dose; for a 5-year-old, four times the adult dose.

    Pregnant women also take up more iodine 131 in the thyroid, especially during the first trimester. The iodine crosses the placenta and reaches the fetus, and the fetal thyroid takes up more and more iodine as pregnancy progresses. During the first week after birth a baby’s thyroid activity increases up to fourfold and stays at that level for a few days, so newborns are especially vulnerable. Women who are breast-feeding will secrete about a quarter of the iodine they ingest into their milk.

    The compound potassium iodide can protect the thyroid by saturating it with normal iodine so it will have no need to soak up the radioactive form. People in Japan have been advised to take it. Scientists say that if it is in short supply and must be rationed, the pills should go first to pregnant women and children.

    The 1986 accident at Chernobyl caused an epidemic of thyroid cancer — 6,000 cases so far — in people who were exposed as children. The risk in that group has not decreased over time, and many more cases are expected. The culprit was milk produced by cows that had grazed on grass that was heavily carpeted by fallout. The epidemic could probably have been prevented if people in the region had been told not to drink milk and if they had been given potassium iodide.

    The warning applied to the 23 wards of Tokyo, as well as the towns of Mitaka, Tama, Musashino, Machida and Inagi to the west of the city.

    After the announcement on Wednesday, at the Lawson convenience store in the Tsukiji neighborhood of central Tokyo, the shelves were about half-stocked with water. A clerk said he had just restocked them an hour before.

    “People came in and cleared us out in the first hour after the announcement,” he said, saying he did not want to be identified because he did not want to anger his boss. “They were taking 20 or 30 bottles at a time.”

    Outside the store a man struggling to load more than 30 half-liter bottles onto his bicycle said he had bought the water for his wife, who is seven months pregnant.

    Around the corner, at an AM/PM convenience store, the bottled water section of the shelves was bare except for nine half-liter bottles of sparkling lemon-flavored water.

    With water disappearing from store shelves, the Tokyo city government acted to calm fears, saying it would begin distributing 240,000 bottles of water on Thursday to families with children younger than 1 year, the broadcaster NHK reported. There are about 80,000 such children in the affected zone, NHK said.

    Outside Tokyo the government said it had found radioactive materials at levels exceeding legal limits in 11 vegetables in Fukushima Prefecture, the Kyodo news agency reported. Shipments of the affected vegetables from there ended on Monday.

    On Wednesday Prime Minister Kan also suspended shipments of raw milk and parsley from neighboring Ibaraki Prefecture, Kyodo reported.

    The United States Food and Drug Administration said on Tuesday that it would prohibit imports of dairy goods and produce from the affected region. Hong Kong also banned food and milk imports from the area.

    Mr. Kan’s office said Wednesday that rebuilding after the 9.0-magnitude quake and tsunami, which ravaged the northeastern coast of the main Japanese island of Honshu, would cost up to $309 billion. The World Bank, citing private estimates, said on Monday that the figure could reach $235 billion.

    The economic cost of the disaster has hit the Tokyo Electric Power Company, which operates the crippled nuclear plant and is in negotiations with its bankers for loans of as much as $24 billion, according to a person with direct knowledge of the situation who asked not to be identified.

    The Associated Press reported on Wednesday that the official death toll from the disaster had been raised to more than 9,500, with more than 16,000 people missing, although officials said there could be overlap between the figures.

    Meanwhile, strong earthquakes hit the northeast coast on Wednesday. A 6.0-magnitude quake shook Fukushima Prefecture in the morning, according to the Japan Meteorological Agency. That was followed by a 5.8-magnitude tremor about 20 minutes later.

    Scientists have warned that aftershocks from the March 11 quake could continue for weeks, possibly months.

    David Jolly reported from Tokyo, and Denise Grady from New York.

    Keith Bradsher and Kevin Drew contributed reporting from Hong Kong.

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