— The discovery of elevated levels of radiation in ocean water near the damaged Fukushima Dai-ichi nuclear complex has some Americans wondering if they’ll have to give up sushi and other types of seafood imported from Japan. Radiation has also found its way into spinach and raw milk. But experts say that at current levels, the contamination holds no risk for American consumers and only a minor, manageable, risk for people living near the damaged nuclear complex.
While radioactive iodine 131 and cesium 137 have been detected in vegetables and plants near the stricken nuclear reactors, the levels are low enough that they don’t pose a health threat at the moment, says Andrew Maidment, an associate professor of radiology and chief of physics and radiology at the University of Pennsylvania. Of course, that could change if the situation at the plant worsens.
Already, Japan has banned sales of milk and spinach in the regions near the nuclear power plant.
As for seafood, the Japanese are currently monitoring radioactivity in the waters near the power plant and are reporting results to the International Atomic Energy Agency.
Elevated levels of radiation were detected in seawater samples taken Tuesday near the damaged plant, although officials said there was no cause for alarm.
The ocean's immense size would disperse the radiation so fish should not be in danger even if the levels do go up, said Maidment. However, shellfish could pose a problem.
“You might see a problem with clams and scallops,” he explains. “They are farmed in very shallow water very close to the shore. So we’ll have to rely on (Japan's) surveillance system.” If contamination is spotted in shellfish, Maidment says the Japanese will stop exporting the seafood, but, again, very little is exported from Japan to the U.S.
The Asian countries surrounding Japan — including China and South Korea — have begun radiation monitoring of food imports from Japan. The World Health Organization advised on Monday that Japan should quickly ensure that no tainted foods are sold, to protect those living near the affected area from consuming large quantities of those products. But in the U.S., where foods from Japan account for less than 4 percent of all imported foods, there is "no risk to the U.S. food supply," the U.S. Food and Drug Administration said Monday.
Levels set low
Ever since the Chernobyl disaster in 1986, when it became clear that contaminated food could lead to cancers, government agencies around the world set a very low threshold for triggering actions such as banning sales of radiation-tainted foods, says Norman Kleiman, a environmental health scientist at the Mailman School of Public Health and director of the Eye Radiation Environmental Research Laboratory, both at Columbia University.
“Those levels are orders of magnitude below the point where you can detect an actual health effect,” Kleiman says. “They are set very low so that we can protect those who are the most susceptible — children and pregnant mothers.”
But what’s being measured in Japan is far less than what was found in the areas surrounding Chernobyl, Kleiman adds. So, even though the levels are above normal, they are still low enough that you would have to consume large amounts of tainted foods to raise your risk of cancer, Maidment says.
All food contains some sort of radiation, Maidment noted, as do many products we keep in our houses. Bananas, for example, contain a radioactive form of potassium. And it's not just food; granite counter-tops are constantly emitting a weak stream of radiation.
“Those counters are the single most radioactive material you bring into the house,” Maidment says. “You prepare food on them and you don’t even think about it.”
The issue with radiation is dose, experts say. And right now, the dose Americans could get from the tainted foods in Japan is very low.
Beyond this, the most common form of contamination — iodine 131 — is an isotope that decays to its non-radioactive form very quickly. “It will be down 100-fold in two months,” says Maidment. “And that’s why it makes sense to use contaminated dairy products for powdered milk or cheese. By the time the cheese and powdered milk are consumed, they will be fine.”
If the Soviet government had told people about the radiation leaks right after the Chernobyl explosions, many thyroid cancers could have been prevented, says Dr. Yuri Nikiforov, a professor of pathology at the University of Pittsburgh Medical Center. Nikiforov, a freshly minted doctor practicing in Belarus when the Chernobyl accident occurred, saw first-hand the damage iodine-131 could do to children.
“After Chernobyl, there were about 6,000 cases of thyroid cancer and those were mostly in individuals exposed at a very young age — children under 5,” Nikiforov says. “Half of those might have been prevented if the children had been kept inside and told not to drink fresh milk.”
That’s exactly what Japanese parents should do if iodine 131 levels climb, he says.
But based on the experience with the Soviet reactor disaster, there probably won’t be a problem with ocean-going fish, Maidment says. “After Chernobyl, there wasn’t much radioactivity measured in fish from the Baltic Sea,” he adds. “If there wasn’t a problem in the Baltic where the refresh rate isn’t huge, there probably won’t be a problem in the waters off Japan.”