Tuesday, June 1, 2010

A Radioactive Fish Story

The Strontium Fish from the Connecticut River

There was a fish caught in the Connecticut river. It had radioactive strontium in its bones. How much radioactive strontium? The measurement was 59 picocuries per kilogram of fish. Or maybe it was 59 picocuries of strontium per kilogram of fish bones. I couldn't completely understand this sentence:

Irwin said the 59 picocuries per kilogram found in the perch's bones was actually at the low end of measurements taken from fish caught even much farther from nuclear plants.

Bill Irwin made the above statement about the Connecticut River fish. He is the radiological health chief in the Department of Public Health in Vermont.

Meanwhile, the radiological health chief of New Hampshire, Michael Dumond, had this to say about the strontium in the fish:

"It's clearly consistent with the background levels from Chernobyl and weapons testing that went on until 1965."

Similarly, a consultant in radioactive testing, John Till, president of South Carolina-based Risk Assessment Corp. said that the amounts of strontium were too tiny to be a concern. Remembering that a pico is a trillionth of a curie, "tiny" is indeed the correct word.

If there had been 1000 picocuries per kilogram, we would have a billionth of a curie per kilogram in the fish's bones. Thank heavens, there were only 59 picocuries. 59 trillionths! Whew!

As I investigated, by the way, I realized that the confusing sentence about picocuries in fish bones was correct. The reporter referred to picocuries per kilogram of bone. Similar measurements of radioactive strontium in fish from the Hudson River ranged from 200 to 270 picocuries per kg of bone, while measurements of strontium in the flesh ranged of those fish ranged from undetectable to 8 picocuries per kg.

Helen Caldicott

In a rational world, the story might end there. There are incredibly tiny amounts of radioactive strontium in the fish. Three professionals, one from Vermont, one from New Hampshire, and one from a consulting company, said the equivalent of: "Don't worry about eating the fish. The fish are fine." The amounts of strontium are consistent with background radiation from old atomic testing.

However, that would have been a rather one-sided story, so the enterprising AP reporter called Helen Caldicott at her home in Australia.

We all know what Caldicott said: Be afraid. Be very afraid.

(rephrased by me of course, not a quote)

However, I must give one of Caldicott's statements some respect. Irwin said they hadn't been testing the fish in the river until recently, and Caldicott said that since this was the first fish they tested, they didn't have a baseline for comparison of strontium in fish. Caldicott's implication was that the plant is leaking strontium like crazy. Nevertheless, she was right about the baseline. You don't have a baseline when you catch the first fish, and that's a fact.

Getting a baseline for radioactive strontium in fish due to fallout. How hard can it be? I have access to Google. I decided to try.

Update: Arnie Gundersen feels the fish "raises a lot of concerns." A great blogpost, Blinky, on this fish story in Capacity Factor.

Strontium in Fish

How hard can it be? Very hard.

The first thing I noticed is that most of the strontium-in-fish stories were repeats of the same AP story that I referenced above. Google "advanced search" came to the rescue. I looked for strontium in fish without the word "Vermont" in it, and I got some moderately useful results.

The first was the one listed above: fish in the Hudson, near and far from Indian Point. 200 t0 270 picocuries per kilogram in the bone, less than 10 picocuries in the flesh.

Then there was an entire set of literature about tracing fish lives through the strontium in their ear otoliths (who knew?) Turns out that natural strontium isotopes vary in different areas, and you can trace a fish's migration by the measuring the isotopes in the layers of strontium in its ears.

I also learned that strontium is necessary for reef building organisms, and you can buy strontium to add to your advanced aquarium. Similarly, I learned that fish segregate strontium to their bones and their scales, parts of the fish that we rarely eat.

Unfortunately, there really does not seem to be baseline measurements of radioactive strontium in fish. I found fish measured in the Hudson River near Indian Point. I found warnings about removing the bones from fish from the Savannah River before eating them. I even found an article about fish in the Chernobyl exclusion zone. In other words, nobody measures the radioactive strontium in fish unless there's some reason to believe there might be some radioactive strontium in the fish.

Or as my friend Howard said: "Why don't they measure some fish from Lake Champlain for a baseline?" I agree.

Radioactive Strontium and Food

Finally, after all of this, I found radioactive strontium as a toxic substance in the Center for Disease Control archives. A quote from section 1.3 of their toxic assessment:

90Sr is found nearly everywhere in small amounts from past nuclear accidents and fallout from nuclear explosions. You can be exposed to low levels of 90Sr by eating food, drinking water, or accidentally eating soil or dust that contains 90Sr. Food and drinking water are the largest sources of exposure to 90Sr. Because of the nature of 90Sr, some of it gets into fish, vegetables, and livestock. Grain, leafy vegetables, and dairy products contribute the greatest percentage of dietary 90Sr to humans. The concentration of 90Sr in fresh vegetables grown in the United States is less than 9 pCi (or 0.3 Bq) in 1 kg of dried vegetables (in a hot oven). The intake of radioactive strontium for most people will be small.

In other words, the picoCuries of strontium in fresh vegetables (less than 9 picocuries per kilogram) is about the same as in Hudson River fish (less than 10 picocuries/kg in the flesh). Fish are not a source of radioactive strontium in the diet.

The Other Fish Story

This "radioactive" fish was truly Much Ado about Nothing. I wasted my time with fish ear-bones and picocuries. There is no baseline for strontium in fish, but considering the tiny amount of radioactivity present, there probably doesn't need to be a baseline. There's less radioactive strontium in fish flesh than in fresh vegetables. In either case, we are talking about less than ten trillionths of a curie. (1o picocuries).

Meanwhile, the entire Gulf of Mexico is being contaminated by carcinogenic, toxic oil. Fisheries are being wiped out and may not recover for decades. I don't like to knock other technologies (nuclear good! everybody else bad!) There's no free lunch, and everything has its downside. And yet, when I think of the truly horrible devastation in the Gulf, I wonder how Vermonters can waste time and energy on the picocuries in this fish.

I imagine myself back in geothermal energy, at the geopressured zones near Houston. I remember eating the most magnificent seafood I have every had in my life. Houston has restaurants that serve seafood Cajun style, French style, Japanese style. Every style. You name it. That is a city where they know how to cook fish.

Is that world gone forever? And all the people who made a living at catching fish and cooking it and serving it in little tiny restaurants or fancy white-tablecloth restaurants. Is that world gone? Has our thirst for oil destroyed it?

I believe that more nuclear power and less oil and gas drilling would be a very good thing for the world.

Postcard image from the Safe and Green Campaign, aka the Anti-Vermont Yankee walkers. I think the image is supposed to show that Vermont Yankee is ripe for a disaster. To me, it shows that so many other disasters have happened, and all Vermont Yankee has done is release a small amount of radioactivity to the ground within the plant boundaries.


DV8 2XL said...

Half the problem is that by their very nature, radioactive substances can be detected in vanishingly small quantities.

But also, along with a baseline value for the Sr-90, I'd be demanding that they run an assay for the amount of Hg in the flesh of these fish that might have come from any dirt-burners in the area.

Fordi said...

59 pCi/kg is about 2 Bequerels (decays per second) per kilogram.

In terms of ⁹⁰Sr, that's roughly 1 part per billion, or about the same contamination you'd get if you dropped a grain of salt into an inflatable kiddie pool.

⁹⁰Sr undergoes β- decay at an energy of 0.546 MeV. That means about once per second, an electron is ejected from each half-kilogram with enough energy to increase the temperature of that fish's bones by 9.5×10‾¹⁶ K, or about a quadrillionth of a degree fahrenheit - roughly 1/3rd the thickness of the line between hot and cold in your shower.

Aaron Rizzio said...

And I'll bet the fish are also riddled with potassium-40 and carbon-14. I recall the suggestion made by one wag some time ago that the term "Banana Burden" should be used by the scientific community to relate such small measures in easily related unit increments for the news media to understand (e.g.the perch would be <2/100ths, less than 2% of a banana's 3,520 pCi/kg of k-40 alone). Also reminds me of when supermodel Christie Brinkley tested the water off
Long Island Sound (adjacent to Millstone) and found uranium in the seawater and got media coverage for her implication that the NPP was somehow leaking uranium into the ocean. Of course some 4.5 billion tons of uranium is dissolved naturally in the sea, perhaps the oceans will be a major uranium ore in the far future.

Kudos also on relating the info on natural strontium found in fish ear otoliths, you learn something new every day on the internets.

Meredith Angwin said...

Thank you all for the very helpful analyses of that fish and pointing out all the implications it (doesn't) imply.

Fordi, I saw you are a blogger, and I want to say how much I enjoyed your blog about closing the fuel cycle.


I have added your blog to my Favorite Links list.

By the way, people may or may not have noticed that I am aiming at more local blogs on my blogs list, and putting more general energy or nuclear blogs on my links list. However, some general blogs cover VY and Indian Point regularly, so they stay on my blogs list. (Yes, it is confusing where a link should go.) My blog list includes blog post updates. I am trying to make sure my blog list is interesting for people in Vermont and New Hampshire.

I love readers from everywhere, though, not just around here! My blog list was getting too long, and I had to make some decisions on how to manage it. This is my decision for now, because this blog is ultimately about supporting Vermont Yankee.

David said...

I want to comment on the cartoon.

When a bridge collapses we ask why and repair it. When a levee breaks, we ask why and repair it. When a mine explodes, we ask why and increase the protections for it. When a nuclear power plant has a very small leak we cry "The World is Ending!!" and close it down.

Robert Hargraves said...

How many picocuries of Sr-90 in human bones?

Wormwood Forest discusses several orders of magnitudes of Sr-90 in the bones of the animals in the animals in the (human) exclusion zone around Chernobyl; no perceived ill effects.

The body absorbs Sr when there is not enough Ca in the food. Take your Caltrate. (HaHa)

Half live is 30 years, so Chernobyl Sr-90 is half gone. Atmospheric nuclear testing Sr-90 is 75% gone. However the southern hemisphere atmosphere does not mix with that of the northern, so if you are concerned buy property in Argentina.