Tuna safe despite Japan radiation leak, researchers say

By WesCom News Service August 28, 2013 02:00 pm

Go right ahead and enjoy that albacore tuna.

That’s the message an Oregon State University researcher has for those concerned about recent reports that the Fukushima nuclear reactor in Japan is leaking millions of tons of radioactive water into the ocean every day.

“Most of the articles about Fukushima have blown the situation out of proportion,” said Delvan Neville, a radioecologist and doctoral candidate at the university in Corvallis. “They do have some amount of radioactivity moving from the tanks. But the numbers that they’re publishing is from (material) right at the source.”

The estimated rate of the leak is .3 terabecqueral (Bq) per month — compared to the rate of 5,000 to 15,000 Bq released March 11, 2011 when the earthquake and subsequent tsunami devastated the plant and forced its closure.

Officials in Japan have since been dumping tons of water in the reactor to cool its cores, and are running out of tanks in which to place the contaminated water. Some of it has been leaking, and attempts to keep it out of the groundwater and subsequently, the ocean, are proving unsuccessful.

“This situation doesn’t feel like it’s in any way been resolved,” said Leesa Cobb of the Port Orford Ocean Research Team and the wife of a fisherman. “It’s persistent. We’re getting more questions about this when we sell our fish at the farmer’s market and at the food bank. We’re looking for good information about how to respond.”

On the ground

Neville said he believes most of the news coming out of Japan is accurate — but it’s distorted.

The most reported news is that Japanese officials at the plant can’t keep up with the amount of contaminated water that needs to be put in tanks, much less the water that’s leaking from some that have been sitting at the site for months. Other reports say contaminated water is flowing over a protective barrier and into the sea. Yet another indicates radioactivity in underground passageways is 16 million times higher than what is acceptable.

“Some of it is making its way to groundwater,” Neville said, “but the quantity of radioactivity? It’s a drop in the bucket.”

The radionuclides of concern are cesium 134 and 137, and strontium 90, which can collect in the fatty tissue and bones of fish. And the higher up the food chain the fish lives, the higher the concentration that collects in the animal.

But it’s not enough to cause concern, Neville said.

“We all have those in our bodies right now,” he said. “It’s in all the food we eat, all the water we drink.”

That was backed up by Dr. Nicholas Fisher, a distinguished professor in the School of Marine and Atmospheric Sciences at Stony Brook University in New York, who released a similar report.

“In estimating human doses of the Fukushima-derived radioactive cesium in bluefin tuna, we found that heavy seafood consumers, those who ingest … 273 pounds a year  — five times the U.S. national average — even if they ate nothing but the contaminated bluefin tuna off California, would receive radiation doses approximately equivalent to that from one dental x-ray and about half that received by the average person over the course of a normal day from a variety of natural and human sources,” Fisher said. “The resulting increased incidence of cancers would be expected to be essentially undetectable.”

The highest concentration Neville’s seen in albacore is 1.18 Bq per kilogram.

“That’s not really high,” he said. “It’s four times what it was before Fukushima, but it’s a very small trace. The leak would have to be 100 times worse than it is, or it would have to continue on the order of decades to compare to what was in the original release. I don’t expect to see the influence of that leak on this side of the Pacific.”

 Eating one pound of albacore contaminated with the highest level of cesium his studies have ever witnessed would result in a radiation dose of .0007 millirems, Neville said. The FDA limit on cesium in food is thousands of times greater.

Tuna, in particular, migrate from the east coast of Japan to the west coast of North America in a matter of days, making it easy to test the fish that is among the most popular fish-foods in Asia.

Neville said he understands why people are concerned, and why they wonder if the information being received from Japan isn’t being distorted to avoid panic.

True data wanted

“There’s a real lack of information,” Cobb said of the times she’s asked about the fish she sells. “There’s the cultural (aspect); the Japanese want to save face. Even if people said, ‘Let’s really deal with this (internationally),’ what would they do? This will scare you to death, just looking at Fukushima.”

The ocean is a vast, deep pool of water, scientists note. Several hundred tons of contaminated water is easily diluted. And while Japanese officials have urged their citizens not to eat fish from the ocean near the plant, that is not the case here.

“Before this happened, I would have said to anyone, ‘If you want to get really healthy food, get it from the ocean,’” Cobb said. “This isn’t L.A., where you’re dumping your garbage in the ocean. This is a really pristine place. We can’t say this anymore. And it could impact the whole world.”

She said officials here discovered radioactivity had made it across the ocean when it showed up in cow’s milk in Washington.

“We knew it made it across the ocean,” Cobb said. “But then it just fell off the radar.”

Neville said he was more confident in Japan’s data after Oregon State sent vessels to the area in 2012 to test fish and their numbers matched those of the Asian scientists. 

“I personally wouldn’t eat some of the fish in the exclusion zone, but there’s a reason there’s an exclusion zone,” he said. “I would like to see more access with people not related to TEPCO (the nuclear facility’s operator).”

The fish being caught on this side of the ocean are no more radioactive than tuna people ate in the 1990s — and those fish absorb traces of radioactivity released by materiel after weapons testing in the ocean from the 1940s to 1970s.

The report that particularly has him frustrated originated in California earlier this summer claimed radioactivity in bluefin tuna had increased dramatically since the reactor failure two-and-a-half years ago. The report was disseminated to a group of marine biologists.

“If you’re not an expert ... the average person is terrified of it,” Neville said. “Even other scientists who aren’t in the field of radiation are surprisingly ignorant of radiation. Every time I mention cesium in albacore, they say, ‘Oh, my god; are they still fit to eat?’ And, I’ve heard, other people just want to be famous, to have their names attached to reports.”

It is possible U.S. scientists could see contaminated fish as early as 2014 or 2015, he added, but the levels still won’t be anywhere near dangerous.

“There will be individuals who say, ‘I’m not going to eat that,’” he said. “But they don’t realize. They’re radioactive too. You can’t avoid being radioactive.”