A few weeks after the December disaster in Tennessee, in which a ruptured waste "containment pond" at a TVA power plant spilled over a billion gallons of liquefied coal ash into the Emory River and over 300 acres of the surrounding community, I blogged about the health dangers posed by the pollution. Back in January, NRDC arranged to have environmental and health scientists from Duke University travel to the disaster site and conduct tests to determine the toxicity of the sludge. Duke's initial findings were that radium and arsenic levels were high enough to pose a risk to people exposed to dust and river sediment in the area of the massive coal ash spill.
Now comes Duke's final study on the potential human health effects from the spill, published in this month's issue of the journal Environmental Science & Technology. The study's lead author, Dr. Avner Vengosh, said the research concludes that "although you may stop the emission of toxic elements from coal-fired power plants into the air, they remain in the fly ash that gets stored in power plants' containment ponds, and may still end up in the environment."
This the first peer-reviewed, double-blind research paper to examine potential environmental and human health impacts in the immediate aftermath of the spill, according to Duke officials. It involved laboratory analysis of toxic elements -- including radium, arsenic and mercury -- in ash, sediment and water samples collected from waterways dammed by the sludge spill, as well as and from multiple locations downstream and upstream on the Emory and Clinch rivers.
Soon afterwards, medical researchers from Duke's cancer center and environmental engineers from Georgia Tech joined Vengosh's team to conduct a more detailed assessment of the spill's potential impacts on environmental and human health. Their analysis of ash samples revealed that the spilled sludge contained high levels of toxic metals and radioactivity, including 75 parts per million of arsenic, 150 parts per billion of mercury, and eight picocuries of per gram of total radium. (A picocurie is a standard measure of radioactivity.)
While the sludge remains wet, risk of exposure to its toxic contents via inhalation remains slight, according to Vengosh, but the risk increases as the ash dries up. That's when very small particulates -- essentially contaminated dust -- can be inhaled into the lungs. As Dr. Vengosh explains:
"Our study highlights the high probability that as the ash dries, fine particulates enriched with these elements will be re-suspended in the air as dust and could have a severe health impact on local residents or workers who inhale them. The smaller the particulate, the higher the concentration of trace metals and radioactivity it contains. Particulates small enough to be inhaled into the lungs could potentially have tenfold the concentration of these elements as the samples we measured."
The study points out that exposure to fine particulates can pose risks for people with diabetes, vascular disease or pulmonary diseases or infections.
[UPDATE: More than 100 local residents worried about the health impact of the coal ash spill in Tennessee have signed up for free medical screenings.]
Based on Duke's recommendations, the TVA cleanup reportedly has focused on preventing the spilled ash from becoming airborne by, among other things, using road vacuums and water trucks to suppress dust generation by vehicle traffic, wetting ash areas with truck-mounted water cannons, and establishing vegetative cover for longer-term dust management. TVA, along with state and federal environmental agencies, has also established a comprehensive air-monitoring program in the spill area -- and thus far there have been no reported air quality violations.
In addition, Duke's study shows that some toxic elements like arsenic are highly mobilized from the ash. While high levels of toxic elements were recorded in the tributary water, the study finds that due to massive dilution these concentrations do not exceed maximum contaminant level for safe drinking water in the downstream river water. However, Duke warns that high concentrations of mercury in the downstream river sediment could pose a serious long-term threat for fish populations and aquatic ecosystems in the Clinch and Emory rivers.
The bottom-line, in the words of Dr. Vengosh, is that the TVA spill is a "wake-up call." While this particular disaster sheds light on the significant potential environmental and health impacts of coal ash, it's important to realize that there are hundreds of similar storage ponds like it all over the country.
The EPA has pledged to propose new regulations by the end of the year to treat coal ash -- for the first time ever -- as hazardous under federal law. That's a good thing, and it's about time. You can help NRDC help them along by taking action here.
Above all, the Kingston disaster and the ongoing threat posed by coal ash waste should spur our leaders to think twice about rejecting a new, clean energy path in favor of dirty and dangerous coal power.