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Post-Fukushima Food Monitoring
Cindy Folkers
Radiation from Fukushima reached the United States directly, including the radioactive isotopes iodine-131, cesium-134, and cesium-137. Iodine-131, due to its eight-day half-life, was a health threat in the first few months after the accident began. While it no longer poses a new exposure risk, those who were exposed to iodine-131 during this early time should continue to be monitored for diseases, such as thyroid disorders, which could manifest years after this initial exposure. Cesium-134 has a half-life of about two years and cesium-137 a half-life of about thirty years. Both will continue to pose a health risk for a few decades (cesium-134) to hundreds of years (cesium-137). Going forward, we must assess how cesium becomes concentrated or biomagnified in the environment over the long term and where it might enter our food supply.
Certain types of radiation that would be less damaging outside our bodies can become much more damaging if inhaled or ingested since there is nothing inside our bodies to block this radioactivity. Each disintegration, or “hit,” represented by a becquerel, may cause damage and disease. Because some radiation is blocked more easily, it is challenging to measure certain radionuclides inside food if this is the only type of radiation that they emit.
In general, gamma radiation is easier to measure because it travels more easily through most material, including the flesh of an apple or a fish. This makes gamma radiation the obvious choice for testing because the food samples require less preparation.
The radionuclide cesium-137 emits a gamma ray and is therefore the radionuclide most often measured. Even if you do not detect the cesium gamma, this does not mean that the food does not contain other radioisotopes that are of concern, such as strontium-90 or plutonium-239. In fact, as Fukushima continues to spew radioactive isotopes, concern is growing among experts that in addition to cesium, other radioisotopes, such as strontium-90, will start to appear in greater quantities, further threatening our ocean food supply. Measuring food for just gamma radiation therefore has serious limitations, but it is a reasonable starting point in any food-testing program.
Fukushima is not the only source of cesium contamination. We have been exposed to man-made radiation for generations from a number of different sources. Atomic bomb blasts worldwide have released 954 petabecquerels of cesium, while every nuclear power reactor releases radionuclides into the water and air as part of its operating plan. It does not take an accident to release this material, although there have been plenty of those. A total release amount for cesium-137 and cesium-134 for the U.S. nuclear power reactor fleet is currently unavailable and would have to be calculated. It would be based on questionable effluent-release data collected by the nuclear power industry, not independent parties.
Chornobyl released 85 quadrillion becquerels of cesium-137 with a margin of 26 petabecquerels or 26 quadrillion becquerels. Fukushima released into the air and ocean 500 quadrillion becquerels of noble gases, according to a TEPCO press release. Meanwhile, highly contaminated water from the ruined reactors continues to be released with no sign that it will stop, and in fact, for some isotopes, such as strontium-90, the releases appear to be increasing. TEPCO has underestimated the initial releases from Fukushima, and there is no evidence that they are being truthful about current releases. These releases continue with no sign that TEPCO has control of the situation and with former nuclear officials from the United States encouraging them to release all of the contaminated water into the Pacific.
There have been a number of food-testing programs. Vital Choice and Eden are private companies that pay to have their products tested. The Berkeley Department of Nuclear Engineering ran about 115 total samples, all of which were from California and mostly from 2011. The U.S. Food and Drug Administration, the Environmental Protection Agency, and the Department of Energy have monitored food, while the National Oceanic and Atmospheric Administration keeps an eye on any contamination that might reach the kuroshio ocean current, which is a fast track to the California Pacific coast, and may start monitoring California coast seawater and sediment. Universities and institutes have done limited testing but need more funding to continue.
These programs have a number of shortcomings. Most samples are only tested for gamma-emitting radionuclides. Testing has been seriously curtailed now even though Fukushima is still spewing radiation and the contamination is becoming entrenched. The EPA was criticized by the inspector general because 20 percent of its radiation monitors in the United States (RadNet) were out of service when the Fukushima catastrophe began. Furthermore, sampling a piece of food every once in a while gives you no real idea of the scope of possible contamination or bioaccumulation and does not pinpoint any potential radiation hot spots.
In other words, the testing of U.S. foodstuffs is inadequate. The U.S. limit for cesium of 1,200 becquerels per kilogram is too high and is not binding, so the FDA can decide to act or not at any level of cesium contamination. It is little different from having no standard or limit at all. By comparison, Japan’s limit is 100 becquerels per kilogram, meaning that food too contaminated for Japan can be imported to the United States. No one has yet explained why children in the United States are allowed to ingest twelve times more radioactive poison than children in Japan. In any case, the release of contaminated food information to the public in the United States is at best paltry, if it is released at all.
After the initial release from Fukushima, radioactive iodine levels in Californian kelp were found to be significantly higher than before Fukushima. The researchers who conducted this study did not test the kelp for cesium, but they should, especially since kelp provides a food source for fish and there is concern that contamination will be concentrated in fish that feed on it.
California grass was found to contain 14 becquerels of cesium-134 and cesium-137 per kilogram. Grass, like kelp, is the beginning of a potential biomagnification chain, which could concentrate cesium in cattle. As the Berkeley monitoring site put it, “for understanding the time-dependence of food chain results, the grass and soil is what to look at.”
Pistachios that were grown in California and shipped to a Japanese supermarket were tested. They were found to contain 18 becquerels of cesium-134 and cesium-137 per kilogram. Beef raised in Japan was tested and approved for sale and then recalled, but not before it was fed to Japanese schoolchildren. This beef had contamination levels between 650 and 2,300 becquerels of cesium per kilogram. All of this beef could have been sold to the United States and the FDA may not have pulled it because, even though a contamination level of 2,300 becquerels of cesium per kilogram is above the FDA limit, this limit is not binding, meaning the FDA can choose to do nothing. Meanwhile, 162 kilograms of green tea were shipped to France from Japan and rejected because of the level of contamination, 1,038 becquerels of cesium per kilogram. The United States would have accepted this tea.