Scientists have known for years that coal — and its burned byproduct, coal ash — contains radioactive elements. In 2009, for example, a group of researchers at Duke University — including Avner Vengosh, professor of earth and ocean sciences — measured high levels of radioactivity in coal ash from a spill at the Tennessee Valley Authority’s Kingston power plant.
But they lacked a complete picture of radioactivity in coal ash — the second-largest form of waste generated in the United States. So, Vengosh and a group of researchers at Duke set out to complete the first systematic study of radioactivity in coal and coal ash from all three of the United States’ major coal producing basins.
The results of that study, published Wednesday in Environmental Science & Technology, show that radioactive elements are present in both coal and coal ash from all three major coal basins — the Illinois, Appalachian and Power River basins. The levels of radioactivity in the coal ash were also up to five times higher than levels in normal soil and up to 10 times higher than in the parent coal itself.
“We found that the radium in coal ash is concentrated during the combustion process, because of the combustion and losing of carbon from coal,” Vengosh told ThinkProgress.
Along with toxic contaminants, like arsenic, selenium, and mercury, coal contains naturally occurring radioactive elements like uranium and thorium, which, when they decay, form chemical by-products like radium. Currently, toxic contaminants have been of the most concern to those monitoring coal ash disposal sites — disposal sites aren’t monitored for radioactivity.
But Vengosh and his colleagues found that when coal is burned, radioactive elements become concentrated in the residual fly ash — particles that, though incredibly small individually, comprise the largest volume of coal ash waste at disposal sites.
That kind of concentration of radioactive particles could have two ramifications, Vengosh told ThinkProgress.
The first is air-borne pollution from fly ash particles. This isn’t really a problem for the United States, Vengosh said, because U.S. power plants have smokestack scrubbers that keep fly ash particles out of the air. But for places like China, where residents are exposed to high levels of coal ash in the air, the radioactivity of the coal ash could pose a threat to public health.
“Once those very tiny particles are being inhaled, they could expose some additional risk of radioactivity,” Vengosh said.
The other ramification of radioactivity in coal ash could come from improper disposal of the coal ash, both abroad and within the United States. Although the disposal of coal ash in the United States is regulated by the Environmental Protection Agency, with the agency’s first-ever regulations on coal ash disposal set to go into effect in October, the ash is often dumped into ditches — sometimes unlined — where it can easily come into direct contact with the environment. Under the EPA’s forthcoming regulations, all new coal ash pits must be lined — but existing pits only need to be cleaned up when they’ve been shown to be actively polluting the environment. And while companies must monitor levels of contaminants in coal ash ponds and nearby groundwater, they aren’t required to monitor radioactivity.
“We have seen evidence that [coal ash disposal] systems are not really closed and protected to the environment, and there is some leeching of other contaminants,” Vengosh said. “Our study suggests that maybe we need to look and do monitoring of radioactivity as well.”
In late July, the House passed a bill aimed at significantly undercutting the amount of federal regulation required for coal ash disposal. Under H.R. 1734, dubbed the “Improving Coal Combustion Residuals Regulation Act,” coal companies could dispose of coal ash directly into water supplies. The bill is currently in the Senate, awaiting action.