Tons of sludge, tons of questions

CU course guides students toward well-founded answers

Just after midnight on Dec. 22, 2008, 5.4 million cubic yards of coal fly ash overflowed a retention pond near the Kingston Fossil Plant in Tennessee. The potentially toxic waste flooded 300 acres, destroyed three homes and damaged 23 others.

The Tennessee Valley Authority, Environmental Protection Agency, activist groups and reporters converged on the scene, which was one of the largest coal-fly ash spills in U.S. history.

But the hazard to neighbors was not clear. The event, which is still being sorted out, made for a perfect case study for Jill Litt’s critical-thinking class, which was to begin in the spring semester, a few weeks later.

Litt, an assistant professor in the Environmental Studies Program at the University of Colorado, teaches a course on “environmental risk and public health.” The Kingston Fossil Plant spill exemplified the nuances of those topics.

Coal fly ash, the residual material after coal is burned and airborne particulates collected in electrical power plants, is not classified as hazardous waste by the U.S. Environmental Protection Agency. It can contain toxic heavy metals and radioactive matter.

But its toxicity can vary. Further, coal fly ash can be rendered inert and reused to make concrete, thereby lowering the carbon dioxide emissions associated with concrete production.

And while simple statements on coal fly ash are elusive, so were data about this spill.

As Litt noted recently, “There were billions of gallons released, but is it hazardous?” This type of industrial disaster could set students up to easily “slide into the advocacy approach,” and to make conclusions about the danger without rigorously reviewing the available evidence.

The course was designed so that students could examine the notion of what is a hazard and to think more broadly about risks associated with materials that are released in vast amounts. That is, such risks may not be tied to short-term human health hazards but rather to long-term ecological and human-health impacts, Litt said.

Furthermore, such hazards may not be adequately addressed through existing regulations, Litt suggested. Challenges like these may prompt society to think creatively about a broader array of indicators that better capture complex exposures and related vulnerability among human and ecological systems, she added.

“What I really wanted was a way for (students) to critically evaluate literature,” Litt said.
In the aftermath of the spill, conflicting statements were more abundant than hard data. “It wasn’t straightforward, … and they had to weigh the evidence.”

To do that, Litt split the class into four groups, each charged with understanding and articulating a different point of view: that of the electrical industry, university and government scientists, a Tennessee citizen group and an environmental group.

Testifying in a mock-congressional hearing in April, each group articulated the perspective it was assigned. Later, each group issued mock press releases summarizing their positions.

The academics, for instance, emphasized that the toxicity of coal fly ash can vary widely, depending on factors such as the type of coal burned, and they emphasized “significant scientific uncertainty” about the long-term effects of the spill.

The environmental group underscored studies linking coal fly ash with disorders in fish. And the TVA group noted its “full efforts” in cleaning up the spill and its intention to implement new systems “to ensure this never happens again.”

Litt, who also serves as an assistant professor in environmental health at CU’s newly established Colorado School of Public Health, challenged her students to sift fact from fiction and to base statements about the health risks of coal-fly ash on reputable studies grounded in toxicology, epidemiology and biostatistics.

To help students sort through this nuanced picture, she explained how epidemiological studies are done, noting the need to understand a study’s bias, sample size and source of funding.

“I got them to step back and say, ‘Wait, it’s not so obvious,’” Litt recalled. “But I had to push.” In the first half of the course, students had to identify hazards, look at dose-response relationships and carefully buttress their conclusions.

Litt noted one difficulty of environmental risk assessment.

“We know a lot about cancer, but we don’t know a lot about non-cancer endpoints,” the data for which are less compelling, she noted. “For every end point, you really have to follow all the studies and piece together animal and human health data, particularly as it relates to cumulative and aggregate risks from a cocktail of contaminants.”

The case study allowed the class to investigate and grapple with these challenges. It also highlighted the legislative challenges associated with fly ash, a “special waste” that is not regulated under the federal Resource Conservation and Recovery Act. Litt observers, “The TVA spill has led to extensive congressional attention to this matter and is forcing action among regulators and policy makers to address the management of coal fly ash.”

Litt is pleased that CU supports critical-thinking classes, which she says “helps to allow students to integrate many of the concepts they learned as undergraduates and refine their oral and written communication skills as well.”

In their careers, the students might find such research and evaluation skills helpful—if, for instance, a boss mentions a recent event and asks for a quick briefing. “We’re often in situations where we don’t have all the data.” When such a day comes, Litt’s students should be ready.