We have all heard about the Fukushima disaster of 2011, resulting in one of the worst nuclear radiation accidents after Chernobyl. Because much of the radiation was released into the ocean, many of us are asking the question – is any fish in the Pacific ocean safe to eat?
In December of 2016, radiation levels were reported for the first time on US coast, coming from Fukushima. The radiation levels were discovered by a team of researchers from the Woods Hole Oceanographic Institution. Ken Buesseler of the WHOI has been tracking the radiation across the Pacific ocean for years. Meanwhile, Canadian researchers of the University of Victoria have also found detectable levels of radiation in Canadian salmon samples. The InFORM project is working to assess radiological risks, given the support of multiple organizations including WHOI. (3)
The Fukushima disaster
On March 11, 2011, a magnitude 9.0 earthquake, one of the largest ever recorded, triggering a tsunami that resulted in the displacement of 150,000 people, 19,000 deaths and severe damage to the Dai-ichi nuclear power plant in Fukushima, Japan. This resulted in four of the six reactors in the plant to release an immense amount of radiation into the atmosphere and ocean. Experts have been sent to try to contain the damage as much as possible, however, the leakage from the power plant continues to be a problem today. One of the concerning outcomes of this disaster is the exposure of Pacific fish to radiation.
Nuclear radiation and why it’s harmful
Damage to the Fukushima reactors released iodine-131, cesium-134 and cesium-137 isotopes in large amounts. These particles are very dangerous to humans because they can mutate our DNA, and are highly carcinogenic because of their mutagenic properties and can result in cell death. Any form of exposure, either from ingestion, breathing or skin contact can put an individual at risk of radiation poisoning. For example, because radioactive iodine-131 is usually absorbed by the thyroid gland, it is strongly associated with thyroid cancer (1).
At the peak of the Fukushima accident, levels of cesium-137 and -134 near the docks at the reactors were 50 million times higher than before the accident, directly threatening the vitality of marine life. Though levels today are thousands of times lower, there is still evidence of ongoing leaks, something that needs to be paid attention to. Cesium-137 has a relatively long half-life of 30 years, meaning that after this period, half of the product is radioactive.
In addition to the Fukushima disaster, nuclear weapons testings in the 1950s and 1960s have also left traces of this isotope even today. Because cesium-134 has a shorter half-life, any amount found in ocean life is traced back to Fukushima, allowing researchers to determine the level of contamination released from reactors sites.
Should we be worried?
Research published in 2016 suggested that the radiation released may have a negative impact on fish but because of strong regulation, the risk to humans is minimal (2). The study demonstrated that freshwater fish closest to Fukushima have the highest risk of cesium contamination, the dangerous radioactive compound released during the disaster. However, the risk diminishes in fish that are further away from this city. Any amount of radiation is dangerous to the body, meaning that fish closest to Fukushima are not fit for human consumption.
Nearly five years after the Fukushima disaster, research has demonstrated that “the overall contamination risk for aquatic food items is very low” and has decreased steadily since 2011. In the study, Japanese researchers created a new method of estimating cesium levels and found that most fish met the criteria for safe consumption. As well, because most of the freshwater species we consume are actually farmed, it is unlikely that the average consumer comes into contact with “radioactive” fish unless they were caught by leisure fishermen.
What can we do to reduce the risk of exposure?
As we are aware of fish migration patterns, it is important to consider the potential dangers of consuming Pacific fish. Because of the biomagnification of the food chain, where low levels of radiation start to increase as higher life forms consume lower life forms, it is best to minimize or avoid large Pacific fish such as tuna, salmon, and tilapia. Smaller fish such as mackerel, anchovies and herring and sardines are better options as they accumulate fewer toxins due to their size.
It may be better to opt for wild-caught Atlantic fish and to consume them in moderation as well.
Yamashita M, Takayanagi Y, Yoshida M, Nishimori K, Kusama M, Onaka T. Involvement of prolactin-releasing peptide in the activation of oxytocin neurones in response to food intake. J Neuroendocrinol [Internet]. 2013 May [cited 2016 Apr 20];25(5):455–65. Available from: http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=3664423&tool=pmcentrez&rendertype=abstract
Okamura H, Ikeda S, Morita T, Eguchi S. Risk assessment of radioisotope contamination for aquatic living resources in and around Japan. Proc Natl Acad Sci U S A [Internet]. National Academy of Sciences; 2016 Apr 5 [cited 2017 Jul 21];113(14):3838–43. Available from: http://www.ncbi.nlm.nih.gov/pubmed/26929347