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Failing the Test: Toxic Metals in Coal Ash

Coal ash contains metals like arsenic, antimony, chromium, and selenium that can pose serious threats to human health, including increased risk of cancer, stomach ailments, and lung and heart problems. The question is, how much of these toxic metals does coal ash contain? In 2009, data generated by the U.S. Environmental Protection Agency, using new testing methods, showed that toxic metal concentrations found in coal ash samples are as much as 1,800 times greater than federal safe drinking water standards. (Read the report.)

That's of serious concern, considering that current methods of coal ash disposal often lead to contaminated drinking water. Though you may not be able to taste elevated levels of arsenic or other metals in your tap water, your health may very well feel the effects.

The differences in toxic metal concentration amounts between safe drinking water and coal ash are huge—like the weight difference between a Miami Dolphin football player and a blue whale. To better understand the magnitude of these differences, consider how a 200-pound Miami Dolphin, symbolizing the amount allowed by federal safe drinking water standards, measures up with some of the ocean's largest creatures:


Levels of  chromium  found in coal ash samples were 73 times higher than the federal drinking water standard. A large full grown orca weighs roughly 73 times more than a 200-pound Miami Dolphin.


Levels of   cadmium  found in coal ash samples were 580 times higher than the federal drinking water standard. A right whale weighs roughly 580 times more than a 200-pound Miami Dolphin.


Levels of   arsenic  and  antimony  found in coal ash samples were 1800 times higher than the federal drinking water standard. A blue whale weighs roughly 1800 times more than a 200-pound Miami Dolphin.

About the Data:

Adding air pollution controls to existing power plants is shifting toxic pollution from the smokestacks to the fly ash, FGD gypsum and other air pollution control residues commonly referred to collectively as "coal ash." Increased concentrations of toxic metals in coal ash increases the potential for them to leach into water.

For decades, the EPA, state agencies and industry relied on a 1990 leach test, known as the Toxicity Characteristic Leaching Procedure (TCLP), which often failed to accurately predict levels of pollutants leaching from coal ash. For years, the National Academy of Sciences and the EPA's own Science Advisory Board questioned the reliance on such an inaccurate testing method for coal ash and explicitly recommended that EPA replace the old test.

In 2006, the EPA itself acknowledged the need for a more accurate and sensitive test and began using an alternate framework. The new EPA proposed coal ash rule explicitly states that "a considerable body of evidence has emerged indicating that the TCLP alone is not a good predictor of the mobility of metals in CCRs under a variety of different conditions."

The EPA's new test method provides a more accurate assessment of the potential of toxic chemicals to leach from the waste, showing that coal ash pollution is an obvious threat to drinking water and in some cases, far exceeds the thresholds for hazardous waste. These new testing methods show that arsenic can leach from coal ash at 3 times, chromium can leach over 1.5 times, and selenium can leach at 29 times the threshold of what is considered hazardous waste.

The EPA's Office of Research and Development tested more than 70 samples of ash and sludge from numerous coal-fired power plants in determining this data. For more details, read the May 2010 Earthjustice report, Failing the Test: Unintended Consequences of Controlling HAPs from Coal Plants.

Graphics: Joshua Herbolsheimer

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