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The bluff collapse at the We Energies power plant Monday exposed coal ash from the 1950s and 1960s, and that has rekindled a debate over EPA standards and the health risks of coal ash.

Officials with the Wisconsin Department of Natural Resources said the impact on human health would be minimal because only an estimated 10 percent of the coal ash made it into the lake. However, the debate over the health implications of coal ash are further underscored by a report by Barbara Gottlieb, an associate professor at Harvard and also the director of environment and health director for Physicians for Social Responsibility and Earth Justice. 

Coal ash contains arsenic, lead, mercury, cadmium, chromium and selenium, which are "known to cause cancer and neurological damage in humans. They can also harm and kill wildlife, especially fish and other water-dwelling species." And if inhaled, some of the "forms of recycling may endanger human health from airborne particles, even where no water is involved," wrote Gottlieb in the report.

However, officials with We Energies disagree with those claims.

Cathy Schulze, a spokesperson for We Energies, said coal ash is not a toxic substance, and isn't listed as a toxic substance by the EPA.

"We even recycle 100 percent of the coal ash we produce," she said.

Schulze points to a fact sheet that outlines how We Energies recycles coal ash by using it to stabilize soil, and in grout and mortars.

When asked about a report written by Gottlieb titled Coal Ash: The toxic threat to our health and environment, Schulze downplayed the findings.

"That’s her opinion and that’s not the EPA's stance … I can’t comment on what the EPA does," Schulze said. "But there are environmental groups pushing for higher stands. However, Wisconsin is among strictest ... I don’t believe there will be a health impact from what has happened in Oak Creek."

Schulze also pointed to a report by TMJ4, which featured a spokesperson from the Racine water utility who was confident that their water filitration system would filter out the coal ash.

Gottlieb said the additional coal ash that went into the lake may not have been a significant amount, but even a one-time level high level of exposure can cause effects and the list of harms with coal ash is long. She also warned that the metals in coal ash can leach into the ground and make its way to the water supply.

"These metals don’t biodegrade and they don’t go away," Gottlieb said. "This is why the pre-existing levels of contamination matter. Compared to the volume of water, this may be an insignificant amount that was put into the water, but we need to talk about these pre-existing levels of contamination. You can’t look at these accidents in a vacuum."