Radioactive Rain Falling on United States

East Coast tests found iodine-131 from Japan in rainwater; California results due out in coming days
By: John Upton

Rain falling on the United States contains radioactive material from Japan at levels that exceed federal safety thresholds.

Federal officials on Tuesday urged calm in the wake of the discovery of iodine-131, which blew across the Pacific Ocean from the stricken Fukushima nuclear power plant, in rainwater.

The tests that detected the radioactive material were conducted by the Massachusetts Department of Public Health and by nuclear power plant operators in Pennsylvania. 

Test results for California have not yet been released, so it's impossible to assess the exact dangers here. The U.S. Environmental Protection Agency plans to publish those results within the next day or so, according to Mike Bandrowski, chief of indoor air and radiation for the EPA's Region 9, which includes California.

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Government officials for weeks have been downplaying the likely health effects of the radioactive fallout on Californians.

The level of radioactive material detected by the East Coast tests, however, “does exceed the EPA’s maximum contaminant level,” Bandrowski said. Because radioactive material degrades quickly, he said the contamination would likely be short-lived. “It’s all going to decay away in two months or so.”

Iodine-131 is among the most toxic particles released during nuclear accidents, according to Daniel Hirsch, a nuclear policy lecturer at the University of California, Santa Cruz. It can build up in thyroid glands, where it can lead to cancer.

“We’ve had immense storms, so there was a large amount of rainfall that potentially brought down a significant amount of radioactivity,” Hirsh said.

The EPA's maximum contaminant limits for iodine-131 assume exposure over the course of a lifetime, according to Bandrowski, who said residents should not be concerned by the presence of the radioactive material for a “short duration.”

The radioactive material is circling the world on jet streams in the stratosphere, which extends about 30 miles above the earth’s surface, and it can be dragged back down to earth by storms, especially after becoming attached to dust or other heavier materials.

In response to the elevated levels of the material in rainwater, the EPA and U.S. Food and Drug Administration say they are increasing monitoring for the material in drinking water and dairy products. The material accumulates in milk after being ingested by cows.

The Dairy Council of California referred questions to the federal government.

“Our testing is in very preliminary stages and isn’t complete yet,” FDA spokeswoman Siobhan DeLancey said in an email. “Test results that we have received from states have not indicated any uptick or hazards.”

Hirsh criticized the federal government for taking several weeks to determine iodine-131 levels in rainwater, drinking water and milk on the West Coast.

“Instead we get assurances before we get data, and the data takes weeks — if it comes out at all,” Hirsh said.

Jet streams carry material from Japan to the West Coast; the Japanese government used them to carry bombs attached to balloons to the U.S. during World War II.

If drinking water and dairy testing had been conducted earlier, and if the results had showed dangerous levels of iodine-131, residents would have known to take potassium iodide pills and stop drinking milk, Hirsh said. Dairy farmers would have known to switch to stored grain as a feedstock instead of allowing their cattle to graze on contaminated grass.

As the nuclear crisis unfolded in Japan, U.S. health officials urged the public not to take potassium iodide.

Spokesmen for the East Bay Municipal Utility District and the San Francisco Public Utilities Commission, which provide much of the drinking water in the Bay Area, said Tuesday that they had not been advised by the federal or state governments to conduct testing for iodine-131 in their reservoirs.

EPA air monitoring stations, meanwhile, continue to detect radioactive material that has blown across the Pacific from Japan.

“There is no health concern from the radiation readings” detected by air monitors, Bandrowski said.