Japanese officials said tap water tests in Tokyo found more than twice the limit for radioactive iodine considered safe for infants. Although the level is not an immediate health risk for adults, officials said babies should not be given tap water. Radioactive iodine can cause thyroid cancer, but officials said there was no reason to worry if infants already consumed small amounts. Authorities are not certain, but they suspect that airborne iodine from the Fukushima Daiichi plant drifted over rivers that feed into Tokyo's water system and then came down in rainfall this week. A direct causal relationship has not been established. However, radioactive iodine was also detected in the water supply in five towns in Fukushima. That's in addition to radiation levels that exceed the legal limits in spinach, broccoli, and raw milk in areas around the plant. U.S. officials have announced a block on Japanese dairy and other produce from the region. Experts say iodine-131 quickly dissipates in the air at the rate of half every eight days. Richard Wakeford, a public health radiologist at the University of Manchester, tells the AP that it's also possible upcoming wind shifts could lower radiation levels.
Considering existing levels, Dr. Lim Sang-moo, director of nuclear medicine at the Korea Cancer Center Hospital, said that the problem might be more mental: "Nobody wants to drink radioactive water," but "it's not a medical problem but a psychosocial problem: The stress that people get from the radioactivity is more dangerous than the radioactivity itself." Convenience stores in Tokyo sold out of bottled water after the news broke, despite a limit of one two-liter bottle per person.
Concerns still remain about radioactive particles in seafood, a staple for the country. Five kinds of materials released by damaged fuel rods were detected in the sea, including iodine-131. Levels of that isotope were 127 times higher than normal in a sample of seawater, but experts say it still poses a limited risk. As fears persist, the crisis has already emerged as the world's most expensive natural disaster, likely to cost up to $309 billion according to the latest estimate.