About 13 years ago, on March 11, 2011, the Fukushima Dai-ichi Nuclear Power Plant disaster released radiation into the North Pacific Ocean. Following that disaster, people from the US West Coast and elsewhere turned to Maine Coast Sea Vegetables for safe, radiation-free sea vegetables, and MCSV began including radiation within their annual safety testing program, something that remains in place to this day. Customers can be reassured that radioactive contamination has never been detected in any of the sea vegetables harvested from the Northwest Atlantic Ocean.
In August 2023, TEPCO, the operator of Fukushima Dai-ichi Nuclear, announced they would begin releasing treated radioactive water into the Pacific Ocean, and by March 2024 the fourth 7,800-ton batch of treated seawater had been released. More releases are planned over the next 30-40 years. These releases have provoked concern with local fishers and countries, especially China, and they raise a number of questions with seafood and seaweed consumers everywhere. Why is treated radioactive water being released into the ocean? What are the implications for seafood safety? Should we be concerned that the seaweed we eat might be radioactive?
Why is Fukushima Dai-ichi releasing radioactive water into the ocean?
When the magnitude 9.0 earthquake struck Japan, it caused a tsunami wave up to 50 feet high in places to batter the coastal towns of Iwate, Miyagi, and Fukushima prefectures in the upper northeast corner of Honshu, Japan’s main island. Fukushima is about 5,300 miles across the Pacific Ocean from the US West Coast. The tsunami overwhelmed the Fukushima Dai-ichi nuclear power plant and destroyed its power supply and back-up cooling systems, causing melt-downs at reactors 1, 2 and 3.
A meltdown is one of the worst kinds of nuclear accidents because it means nuclear fuel elements have overheated to the point where they are literally melting through their containment barriers and releasing radiation into the environment. Left unchecked, a meltdown can lead to a runaway chain reaction and large releases of radioactive gasses into the atmosphere.
Ordinarily, most nuclear vessels are cooled by a jacket of continuously flowing water. The water absorbs heat from the reactor vessel but not radiation, and the heated water can be safely discharged into the environment without causing radioactive damage. This is why nuclear power plants must be located on large bodies of water, whether that be a river, lake, or the sea. Anything that interrupts the cooling process can lead to a meltdown. Ironically, considering the present topic, nuclear reactors in Scotland and elsewhere have had to shut down on more than one occasion when their seawater cooling systems became clogged with seaweed.
When the Fukushima Dai-ichi reactors began melting down, workers flooded them with cold seawater to prevent total meltdown. The reactors have been continuously flushed since that time and will have to continue to be flushed until they are totally decommissioned. When the cooling water contacts the radioactive fuel cores it becomes highly contaminated with radionuclides. The contaminated water is stored in tanks on site. It is then treated through an “Advanced Liquid Processing System” (or ALPS for short) to remove radionuclides. The only radionuclide that ALPS cannot filter out is tritium, a hydrogen isotope, because tritium is incorporated into the water molecules themselves (as the H in H2O). The ALPS treated water is stored in another set of tanks on the site.
ALPS is a pumping and filtration system, which uses a series of chemical reactions to remove 62 radionuclides from contaminated water. However, ALPS is not able to remove tritium from the contaminated water.
All of the water used since 2011 to cool the reactors, about 350 million gallons, is stored on-site in over 1,000 tanks. With space running low, the operators received permission from the International Atomic Energy Agency (IAEA), which is charged with monitoring oversight, to release the ALPS treated water in batches. The water is diluted before release and then diluted again when it enters the Pacific Ocean. Releases will occur slowly over 30-40 years, and not all at once. The releases are monitored to ensure that radioactivity falls below international safety thresholds.
Tritium is a relatively weak source of beta radiation that is unable to penetrate skin, and it has to be ingested in enormous quantities to cause harm. Tritium is also naturally occurring and we’re regularly exposed to some background level. Most scientists believe the releases won’t raise levels much beyond naturally occurring levels and that they pose negligible risks to humans and the environment. So far, this appears to be the case. The IAEA publishes reports about the Japanese monitoring program at this link: https://www.iaea.org/newscenter/focus/fukushima/status-update. Based on this information, the IAEA concluded that radiation levels in the marine environment around Fukushima remain low and relatively stable.
What are implications for seafood safety?
Soon after the Fukushima disaster, the US FDA issued the import alert (IA) “Detention Without Physical Examination of Products from Japan due to Radionuclide Contamination.” The concern at the time mostly involved radioactive iodine-131, cesium-137, and cesium-134, which were detected in the vicinity at levels 50 million times higher than before the disaster. People who enjoyed eating seaweed made the right decision to only use sea vegetables sourced from the North Atlantic, which is about as far from the disaster as possible. People who didn’t normally eat sea vegetables also made the right move when they began including North Atlantic seaweed in their diet, because when the thyroid has enough natural iodine it doesn’t absorb radioactive iodine. Sea vegetables, of course, are one of the best natural dietary sources of iodine available. Many of these people became MCSV customers and some still are to this day.
The FDA deactivated the IA in September 2021 and Japan lifted fishing restrictions from that area the same year. These moves followed a decade of testing by the FDA and Japan that showed radiation levels in seafood from the Fukushima region were no higher than from anywhere else. This article from Woods Hole Oceanographic Institute discusses why seafood from that area is safe. The vast dilution of the Pacific Ocean and the short half-lives of iodine-131 (8 days) and cesium-134 (2 years) are two of the main reasons. Iodine-131 disappears within months, and very little cesium-134 remains after 13 years. Cesium-137 has a half-life of 30 years, but over that time it becomes diluted in the Pacific.
Radiological monitoring immediately after the disaster did show elevated radioactive cesium and iodine in sediments, water, and biota within the vicinity. However, a study done in June 2011, only three months afterwards, showed that levels measured in mussels and seaweed did not exceed 500 Bq kg wet wt., the recommended safety level for seafood consumption. According to one published study, by 2015 radiation levels in seafood species caught in the vicinity of Fukushima were below 100 Bg/kg.
Experts agree that Japanese seafood is safe to eat, poses no radiological threat, and that releases of tritium seawater do nothing to increase the threat. That assessment appears to fall on deaf ears in the neighboring countries of South Korea and China, which have boycotted Japanese seafood. Both countries have had an acrimonious relationship with Japan in the past and up to the present, so politics may be playing a bigger role in their concern than science. Greenpeace has also raised concerns, mainly regarding whether the ALPS treatment is reliable and the trustworthiness of Japanese radiological monitoring. However, this view is at odds with what the majority of scientists believe. The Japan Ministry of Economy, Trade, and Industry maintains a website with FAQs about ALPS treated water and related topics.
Should we be concerned about radioactive seaweed?
Macroalgae can accumulate radioactive isotopes and for this reason seaweed is often used to monitor marine environments following nuclear accidents, such as in the Black Sea following the 1986 Chernobyl meltdown. The Black Sea received about 2% of the released radionuclides, mostly from the Dneiper and Danube rivers, and elevated levels of radionuclides were detected in the benthic brown seaweed Cystoseira sp. collected from the Black Sea several months after the disaster. In this respect, seaweed is no different from other foods that also become contaminated by harmful radiation, such as grains, dairy, and meat. Concern is the proper attitude regarding any food sourced from the vicinity of a nuclear accident. Proximity is a major risk factor and the risk considerably diminishes with distance. This means a radioactive release in one part of the world will not affect seaweed or other foods harvested far from the accident, which is certainly reassuring.
Cystoseira sp., a brown seaweed found in Europe, is commonly
used as a pollution bioindicator. Wikimedia image, originally published in
Johnstone, W.G., Croall, A.: The Nature-Printed British Sea-Weeds. Volume 3. (1868)
Seaweed from the Northwest Atlantic (Iceland, Maritime Canada, and Maine) is at very low risk of radionuclide contamination. Maine’s only nuclear power plant was shut down in 1997, though the site still stores about 550 tons of spent fuel in concrete and steel cannisters. Maritime Canada does have one operational nuclear reactor located near Point Lepreau, New Brunswick, which lies within the Gulf of Maine. Iceland, thanks to abundant geothermal energy resources, has never had a nuclear reactor.
Despite the low cause for alarm, Maine Coast Sea Vegetables continues to monitor sea vegetables from the Northwest Atlantic for radionuclide contamination and post the results. Our monitoring strategy samples species representing each group, environment, and region. More information on our testing program can be found on our Product Testing page.
Wherever and whenever a nuclear accident occurs, one of the best measures one can take to protect themselves is to include a daily ration of sea vegetables in their diet until at least about one month after the incident stops releasing radiation. As mentioned earlier, this helps ensure the body has sufficient iodine reserves to protect it from harmful iodine-131. In addition, as described in our FAQ “Does seaweed protect you from radiation poisoning”, intriguing research from the 1960’s showed that alginic acid, a polysaccharide found in brown seaweed species, could help the body rid itself of radioactive strontium-90. Strontium-90 is an artificially created byproduct of nuclear bomb explosions and nuclear power reactors, though it’s less likely to be released in large quantities from a non-explosive nuclear power plant accident. The Chernobyl incident released significant strontium-90 into the atmosphere because it was explosive in nature, whereas the Fukushima incident released less because it was not explosive. After the Chernobyl explosion MCSV joined with others to send sea vegetable care packages to residents of the Chernobyl region.
Nuclear war is the worst-case scenario for radiation poisoning. Here again, seaweed could help save humanity. In addition to the protection it confers against radiation poisoning, seaweed could help feed the world during the nuclear winter that follows. Multiple nuclear explosions and the cities they burn would release vast clouds of dust, smoke, and particles into the atmosphere. This would reduce sunlight, cool the planet, and decimate agriculture as we know it. A research article titled Seaweed as a Resilient Food Solution After a Nuclear War found that enough seaweed could be grown in tropical waters to meet 45% of global food demand within a short period of time. Paradoxically, the researchers found that seaweed growth increased with severity of the nuclear winter because those conditions favor more ocean vertical mixing and nutrient availability.
Of course, humanity would have to be prepared in advance to build enough seaweed farms fast enough to respond. That seems like a tall order! But we all have the power to prepare for the worst on an individual and family level. Dried seaweed has incredible shelf-life when stored in sealed packaging away from direct light or temperature extremes.
We’ve found sugar kelp or dulse to be quite tasty after 5 years storage, and we suspect this would still be true even after 10-15 years. Although iodine is a volatile element, the few studies done so far indicate that total iodine losses from dried seaweed might top out at 40-50% even after many years storage. Sugar kelp in particular contains plenty of iodine, so even after losing 50% a small serving would still be enough to satisfy ones’ daily requirement. Although we normally like to extol the nutritional, culinary, and medicinal virtues of sea vegetables, they also have the virtue of being a good survival food. So, enjoy them now and into the future!
