Japan Radiation Risks: FAQ
Answers to questions about health risks posed by Japan's damaged Fukushimi Daiichi nuclear power plant.
What kind of radiation is coming from the plant?
There are a number of different radioactive substances that could leak from a damaged nuclear reactor. At this point, radioactive iodine (iodine-131) is the primary component of the leaked material, although there has also been some release of cesium-137.
With a half-life of just eight days, radioactive iodine quickly loses its potency and after a couple of months, is virtually gone. Cesium, however, has a half-life of 30 years, and so can pose a threat to public health for much longer.
“Even so, at Chernobyl if there were going to be major effects from cesium, we should have started seeing significant increases in solid tumors by now,” says Williams. “But 25 years later, we’re only just beginning to see the hints of possibly an increase in bladder cancers. We’re still not seeing if there was a significant impact.”
Are radiation-contaminated foods being imported from Japan?
"Based on current information, there is no risk to the U.S. food supply," the FDA states on its web site.
The FDA is stepping up its radiation screening of product shipments imported from Japan and has programmed its import-tracking system to automatically flag all shipments of FDA-regulated products coming from Japan.
As of March 22, milk and milk products and vegetables and fruits produced or manufactured from the four Japanese prefectures of Fukushima, Ibaraki, Tochigi, and Gunma will be detained upon entry to the U.S., and not released for sale unless they are shown to be free of contamination. “Other food products from this area, including seafood, although not subject to the Import Alert, will be diverted for testing by FDA before they can enter the food supply. FDA will also be monitoring and testing food products, including seafood, from other areas of Japan as appropriate,” the FDA states.
According to the FDA, foods imported from Japan account for less than 4% of all foods imported to the U.S., and Japanese dairy products make up only one-tenth of 1% of all FDA-regulated products imported from Japan. That figure is even smaller at the moment, because the heavy damage done by the earthquake and tsunami has limited exports from the affected region.
Could radiation from Japan's nuclear plants affect the U.S.?
No harmful amount of radiation from the Japan disaster is expected to hit the U.S., experts say.
On April 10, the U.S. Environmental Protection Agency reported that its air monitors have detected “very low levels of radioactive material in the United States consistent with estimated releases from the damaged nuclear reactors.” These findings were expected, the EPA notes, but in response, it has stepped up monitoring of precipitation, milk, and drinking water. This monitoring has also detected low levels of radioactive material, which the EPA says are “far below levels of public-health concern.”
At the University of California-Berkeley, experts in the nuclear engineering department are monitoring radiation levels in the food chain (for example, produce such as strawberries and lettuce), rain water, tap water, and milk. While they have detected elevated levels of certain radioisotopes, they confirm that these levels are still extremely low. For example, they state that “consuming 403 kg of spinach could give you a radiation dose equivalent to a roundtrip flight from San Francisco to Washington, D.C.” In fact, they note, even that risk may be overstated, because it assumes that the person is eating food contaminated at that level for a full year.