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Beware Misplaced Statistics Regarding Coal Ash Risks

Mark Twain popularized the saying that “There are three kinds of lies: lies, damned lies, and statistics.” It’s the last kind that forms the foundation of environmental activist attacks on coal ash.

“The EPA also found that the cancer risk for children exposed to arsenic in drinking water from unlined ash ponds is as high as 1 in 50…” wrote a collection of anti-coal environmental groups this month in a letter to the White House.  The “1 in 50” claim has become a familiar refrain for proponents of a “hazardous waste” designation for coal ash, appearing in almost every news release and winding up in articles like the one in Huffington Post March 24 with the colorful headline: “Even the cows have cancer…”  But what does 1 in 50 really mean?

The statistic itself is from the U.S. Environmental Protection Agency’s 2007 Draft Screening Level Risk Assessment.  This screening tool uses conservative assumptions to guide further risk modeling activities.  It is not intended to document what has actually occurred and is not intended by itself to justify enacting broad regulations.

The statistic also comes with a lot of “what ifs.”  In other words, the 1 in 50 statistic may apply IF coal ash is disposed in a wet pond and IF that pond doesn’t have a liner and IF it contaminates groundwater and IF a child consumes enough of the contaminated water. Taking into account the potentially affected population at the 245 sites evaluated in the Draft Screening Level Risk Assessment, the 1 in 50 risk level equates to one additional person in the United States expected to develop cancer over a 70-year lifetime.

When coal ash is disposed, it should be managed properly to reduce the risk of negative impact to human health and the environment.  EPA studies like the Draft Screening Level Risk Assessment provide important information to be used as regulations are developed. But cherry picking the most extreme statistic from the Assessment and repeatedly using it to stir up fear of coal ash is an exaggeration at best or a deliberate attempt to mislead people at worst.



Posted by: on: Apr 09, 2010 @ 02:48