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Fallout fallacies: How TVA misled on coal ash radiation threat

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duke_collects_tva_ash.jpgA week after a dam collapsed at the Kingston power plant in eastern Tennessee and dumped more than a billion gallons of toxic coal ash waste into the nearby community of Harriman and the Emory River, the Tennessee Valley Authority collected samples of the ash and tested them for radioactivity. The summary of results [pdf] released by the company suggested the risk was minimal, stating that the total radioactivity in the ash was "less than that found in low sodium salt available to consumers on the shelves of grocery stores."

But a new independent analysis of radiation in the ash suggests the company downplayed the real risk.

Scientists from Duke University last week announced that their tests found the ash has radiation levels higher than those found in typical coal ash. The combined content of radium-228 and radium-226 in the solid ash samples they collected from the TVA spill earlier this month measured about 8 picocuries per gram. That compares to the average 5 or 6 picocuries per gram reported by the Environmental Protection Agency in most ash samples from coal-fired power plants.

Produced when the naturally occurring uranium and thorium in coal decays, radium concentrates in the ash when coal is burned. Radium exposure is known to cause bone, liver and breast cancer in humans as well as anemia, cataracts and tooth damage.

"Preventing the formation of airborne particulate matter from the ash that was released to the environment seems essential for reducing possible health impacts," lead researcher Avner Vengosh, an associate professor of earth and ocean sciences at Duke's Nicholas School of the Environment, told Duke Today.

So how is it that Duke scientists are calling for action to reduce health impacts from radiation in the ash when the company is insisting the stuff is no more dangerous than low-sodium table salt?

Because they're comparing apples to oranges.

In its statement on radiation in the ash, TVA focuses on the radioactive element potassium-40, which represents the largest source of radiation exposure in most people. Manufacturers of low-sodium salt use potassium chloride as a substitute for some of the sodium chloride found in regular salt; because a portion of potassium is naturally radioactive, so is the light salt.

But Vengosh's team focused on radium isotopes, which are much more dangerous to human health than potassium-40.

The following table is based on data contained in the federal government's table of radionuclide carcinogenicity -- that is, the likelihood that a particular radioactive element is likely to cause cancer. The "morbidity risk coefficient" is a comparable estimate of the average total risk of experiencing a radiogenic cancer, whether or not the cancer proves fatal.

carcinogenicity_risk_table.jpg

As the federal government's own data clearly shows, radium-226 and radium-228 are much more likely to cause cancer than potassium-40. Compared to drinking water contaminated with potassium-40, water contaminated with radium-226 presents more than 15 times the cancer risk, while water contaminated with radium-228 carries 42 times the cancer risk.

The difference in risk is even more dramatic when it comes to inhalation. Compared to breathing in potassium-40, inhaling radium-228 carries 500 times the risk of cancer, while inhaling radium-226 is 1,000 times riskier. As we've reported, cleanup workers at the site have not always worn protective masks while on the job.

The dramatic difference in risk among the various radionuclides contained in the coal ash was obscured by TVA's analysis, which focused on the most innocuous radionuclide present.

TVA issued a statement last week saying it would review the Duke findings.

In an effort to keep the ash from becoming airborne and being inhaled by people, the company has already sown grass over more than 200 acres of the spill and is spraying water on the ash in work areas.

(In the above photo, taken by Duke University professor Avner Vengosh, graduate student Laura Ruhl collects samples of ash from the TVA coal sludge spill.)

 

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re: Fallout fallacies: How TVA misled on coal ash radiation thre

so basically your own numbers show that the chances of dying from the radiation in the coal ash is virtually impossible unless you eat buckets full of it (and even then far less likely then a thousand other things in life). Your own numbers show that there is maybe a 1/10000 chance someone will die of that? so if a human life is worth say 5 million dollars (a pretty high estimate) then TVA should be fined approximately 500$ for this release of radium?

re: Fallout fallacies: How TVA misled on coal ash radiation thre

Alex, that isn't what these numbers show. First of all, the figures in the chart are for morbidity, not mortality, and thus tell us nothing about anyone's "chances of dying." Second, they measure risk per picocurie ingested or inhaled. Consider the quantity of ash that's been spilled -- more than 1 billion gallons -- and the fact that most of it's still on the ground or in the river ecosystem and not going anywhere soon. The potential for exposure is obviously considerable and needs to be addressed, as the Duke scientists point out. My concern isn't the calculating of punitive fines or putting a price tag on a human life. It's that TVA be honest about the real risk its spill presents and take appropriate action.

re: Fallout fallacies: How TVA misled on coal ash radiation thre

The above article states that the primary risks from radioactivity in fly ash is from inhalation or ingestion of radium-226 and radium-228. This is not true.

The primary risk from exposure to radium-226 and radium-228 in fly ash is from external exposure to penetrating gamma radiation emitted by the decay of radium decay products within the ash. This means that the highest exposure (and risk) would occur simply by walking over the ash.

The wearing of respirators and protective clothing might protect against dust and arsenic exposure, but it would not protect against exposure to penetrating gamma radiation stemming from radioactive decay occuring in the ash underfoot. By comparison, exposure to radium in fly-ash from inhalation or ingestion will be of relatively minor importance.

The size of the radiation dose or the subsequent health risk, will be determined as much by the amount of time spent walking over the ash as by the concentration of the radium in the ash itself.

Although the estimated cancer incidence risk from an ash concentration of 8 picocuries per gram of radium-226 and radium-228 would be higher than what EPA would normally permit for clean-up at a Superfund site, or even for a uranium mill tailings site, it is not as high as what most people encounter in their own homes through the continuous indoor inhalation of radioactive decay products of radon.

Of course, radon itself is a decay product of radium in soil.

The EPA cancer risk estimates listed in the above article are based on a lifetime exposure to radionuclides in drinking water or air. For Superfund clean-up decisions, risk estimates are made for hypothetical exposure durations of up to 30 years. Any actual exposure to the radiation in the coal fly ash spilled near Kingston, TN should be over much shorter periods of time, given that remediation will either remove this material from affected properties and/or restrict access.

re: Fallout fallacies: How TVA misled on coal ash radiation thre

Wikipedia would seem to indicate that the aforementioned isotopes of radium decay through an alpha and a weak beta, neither of which will penetrate your skin. Therefore I have to come to the conclusion that inhalation or ingestion of ash particles which were permanently retained would be required to impart any significant radiological dose. I'm not gonna go through the entire decay pathway looking for gamma emitting decay products, I can't find any right off. I'm not sure if anyone wants to go out with a Geiger counter, but if you want you could go determine the radiation doses compared to background from mere exposure.

A simple search of cancer risk from a medical X-ray seems to indicate that an X-ray risks your life approximately equal to having a kilogram of this ash stuck in your lungs (which would be deadly without the radiation). I'm sure that if this goes to litigation on a radiological basis TVA will be able to bring up hundreds of other things that are more deadly. For example living in Denver due to its high altitude will likely expose you to far more radiation than this spill.

Also, nobody has any reason to be in close proximity to the spill except for TVAs own workers. I'm not sure if any of the people who used to live there are still foolish enough to stay, but they will all be millionaires soon and will have no reason to live next to any ash spill. In all honesty this is the best thing that will ever happen to these people in their entire lives.

re: Fallout fallacies: How TVA misled on coal ash radiation thre

Owen, the trouble with alpha and weak beta emitters is precisely that they're easily absorbed. While fairly harmless outside the body, ingesting them will expose internal parts of the body to those radiations for many half lives, which for these radium isotopes means long after you're dead. The same issues relate to other alpha and weak beta emitters such as tritium (which can't even be detected by a hand-held instrument).

That said, I've been convinced for a long time that government protection figures in many cases represent a knee-jerk reaction because so many people freak out over radiation and don't even realize their own body is radioactive: if this was the case, much of the world would be dead or full of cancer from nuke tests, Chernobyl, etc.

I don't live in the South, but this is just my own opinion after finding this on a Google search.

Mike

re: Fallout fallacies: How TVA misled on coal ash radiation thre

I wanted to focus your attention on two reports of radiation in the ash before it spilled miles up and down stream in the Emory River.
On the TVA web site, they have posted all the documents disclosed to the Tennessee Department of Environment and Conservation (TDEC).
I wanted to focus your attention on two of them.
Please notice that in addition to the pipe containing fly ash being "hot", a specific area of the ash sluice trench was also "hot".
2007/02/09 scrap metal that failed to pass the radiation monitor TVA-00025974
http://www.tva.gov/kingston/tdec/pdf/TVA-00025974.pdf
2007/08/17 scrap metal dumpsters that failed to pass the radiation monitor TVA-00026034
http://www.tva.gov/kingston/tdec/pdf/TVA-00026034.pdf
"Both TVA-Muscle Shoals and the State of TN surveyed and sampled the dumpster located south of the north stack containing demolished sluice line piping. There is only one hot piece in this dumpster (15 uR/hr). They also surveyed piping from the sluice line trench and found elevated readings (18-20 uR/hr) on the line marked U7&8 Regarding the dumpster located at the north end of the Switch yard, we located from whence it came: U7 Precipitator (fly ash) line replacement. The concentration of Ra-226 (88 pci/gm) found in the scrap metal piping from this dumpster coincides with the dose rate levels found on the sluice trench line marked U7&8.
Suffice it to say, no one is sure why the ash is so much hotter than normal (5 pci/gm on average)."
Thank you for all your work in defense of the good folk of Tennessee and Appalachia.
Respectfully and gratefully,
White County Charlie