Tuna Have Become Radioactive in Addition to Mercury

Watch out if you eat a lot of tuna. Yes, tuna do contain high levels of mercury compared to many other fish. But now tuna have become more radioactive.

Fukushima spill traced to tuna

On top of mercury, lead and dioxin, new research has found that tuna are carrying cesium 134 and 137 traced to the 2011 Fukushima nuclear plant radioactive spill. While the levels of radioactivity are claimed not be harmful to humans, the combined toxic load on these fish from our contamination of Mother Nature must now be reconsidered.

Because tuna and other larger fish predators are higher up the sealife food chain, they typically will retain higher levels of the numerous toxins being dumped into our oceans by humans.

Mercury is a good example of this. Recent research from the University of Connecticut’s Marine Science Department found that mercury bioaccumulates greatest within tuna and other larger predators such as swordfish. They found that tuna especially bioaccumulate mercury within their fat cells, providing a significant source of toxicity to humans when humans eat tuna.

The research also found that much of the mercury accumulating in tuna is coming from the upper surface layers of the oceans. Mercury-rich air pollutants land on the ocean surface. From there the pollutants will travel vertically into the lower ocean layers, poisoning smaller fish and bottom-feeders. They eventually saturate the water, and bioaccumulate among the entire food chain.

Other pollutants, including lead, dioxin, BPA and other toxins are also bioaccumulating in these larger fish as well.

The University of Connecticut researchers estimate that atmospheric mercury levels have tripled over the past few years.

The researchers concluded that “migratory pelagic fish such as tuna and swordfish are an important component of mercury exposure for many human populations and therefore any reduction in anthropogenic releases of mercury and associated deposition to the ocean will result in a decline in human exposure and risk.”

Tuna caught off of San Diego tested

Radioactivity now adds another burden to the ocean’s toxin load. The cesium 137 and 134 were found among fifteen tuna that were caught off San Diego in August of 2011. This was about 100 days after these radioactive elements began leaking from the Japanese nuclear reactor following the tsunami in April of 2011.

What are the cesium 137 and 134 levels like today? Has more bioaccumulated through the food chain? We will await further research. In the meantime, the FDA says there is no health hazard.

“I wouldn’t tell anyone what’s safe to eat or what’s not safe to eat,” said lead researcher Dr. Daniel Madigan of Stanford University. “It’s become clear that some people feel that any amount of radioactivity, in their minds, is bad and they’d like to avoid it. But compared to what’s there naturally … and what’s established as safety limits, it’s not a large amount at all.”

Cesium 134 is not a natural radioactive element. It is indicative of nuclear power reactors or other man-made radiation uses.

Cesium 137 is found in nature. While the study found 500% of the normal (background) levels of cesium 137 among the 15 tuna, the amount was still relatively small. The cesium 137 radioactive levels were five becquerels rather than the one becquerel normally in nature. A full 37 billion becquerels equal one curie, and a pound of uranium-238 has 0.00015 curies of radioactivity. In other words, one becquerel is a very small amount of radiation, but remember, this is five times normal.

The age of the fish indicated that they likely spawned off the coast of Japan and then migrated to the coast of California.

How long will the cesium remain in the water?

Like mercury, radioactive cesium will remain in the upper water surfaces, where it will slowly move vertically through the water column to the floor of the ocean. As it falls, like mercury, fish will consume it through the gills along with consuming it by eating smaller contaminated sealife.

So it’s not just global warming we have to worry about. Factories, power plants and industrial waste-streams are spewing mercury, lead, dioxin and now radioactive waste products into the oceans. They are now bioaccumulating within our bodies.

And look out for amalgams causing mercury accumulation in the body as well.

REFERENCES:

Mason RP, Choi AL, Fitzgerald WF, Hammerschmidt CR, Lamborg CH, Soerensen AL, Sunderland EM. Mercury biogeochemical cycling in the ocean and policy implications. Environ Res. 2012 May 2.

Madigan DJ, Baumann Z, Fisher NS. Pacific bluefin tuna transport Fukushima-derived radionuclides from Japan to California PNAS 2012 ; published ahead of print May 29, 2012, doi:10.1073.