West Virginia’s water is starting to look a little clearer – but the fallout is still murky.

More and more people are turning their taps back on as West Virginia American Water gradually lifts “do not use” water orders following the chemical spill from a local storage facility earlier this week. But little information is available thus far about what cleanup procedures might be needed for the Elk River, or what has been done to contain the spill. There is also little information on the chemical at issue, 4-methylcyclohexanemethanol (MCHM), which is used to cleanse coal of impurities.

Spokespersons for the West Virginia Department of Environmental Protection and the U.S. Environmental Protection Agency did not immediately respond to requests for comment on what cleanup procedures were being considered for the spill. Reporters at the scene of the spill are not having much more luck either – on Wednesday, Charleston Gazette reporter Ken Ward Jr. noted the visible lack of EPA officials and little information flowing from the agency.

A spokesperson for MCHM maker Eastman Chemical Co. told the Christian Science Monitor the company thinks the substance will not adversely impact the environment when diluted in water. But the nature of MCHM may mean that it hasn't dissolved all that easily into the waters of the Elk, according to West Virginia University environmental and civil engineer Lance Lin.

“This particular chemical is lighter than water," Lin told the Monitor. "It is only slightly soluble in water, meaning it’s pretty much going to float on top of the river.”

Cleaning a river of toxic substances can be an exhaustive process, and action plans are typically tailored to the contaminant at issue and the unique conditions of the river. Since 2009, General Electric has been dredging the Hudson River to remove polylchlorinated biphenyls (PCBs), a pollutant used in manufacturing. Sediment is scooped up from the bottom of the river, squeezed dry, and sent to a GE processing facility that removes the PCBs. Then the sediment is shipped to a disposal facility outside of New York.

In Michigan’s Tittabawassee River, Dow Chemical Co. has been working to remove a host of chemicals. As MLive explains, in the first cleanup phase aimed at addressing arsenic, tar-like materials, chlorobenzenes and chlorophenols, Dow workers removed contaminated sediment and heavy liquids, and placed clay caps over any heavy liquids that couldn’t be scooped from the river. This year, crews will work on removing dioxin contamination from another segment of the river using a combination of methods. A proposed EPA cleanup plan [PDF] would have workers dig up contaminated sediment in some areas and cover it in others.

Removing contaminated sediment is especially important because pollutants in that sediment may be eaten by small bottom-feeding organisms, which are then in turn eaten by larger ones, which are then eaten by fish, and then eaten by humans. In a process called “bioaccumulation,” the concentration of pollutant can get greater at every step of the food chain, making the risk to top-level predators much greater.

Meanwhile, in West Virginia, officials seem to be scrambling to figure out how to respond to their situation.

On Tuesday, the Charleston Gazette reported that state and federal emergency planners admitted they had not had any strategy in place for dealing with a spill of the kind of chemical used at Freedom Industries. MCHM was not classified as “extremely hazardous” under the federal Emergency Planning and Community Right to Know Act, so officials were not required to have an emergency plan in place.

But “what is particularly maddening and outrageous is that no one – not local or state officials, not the company that owns the storage tank, not the federal government – can say anything even close to definitive about what risk the chemical poses to people, even in the short term, let alone over time,” Environmental Defense Fund scientists Richard Denison and Jennifer McPartland wrote on the EDF blog.

Denison and McPartland point out that there are no publicly available health studies on MCHM. The Material Safety Data Sheet for the chemical, which is generally used to guide workers and emergency personnel on handling chemicals, is weak on specific information (information on carcinogenic effects, actue health effects, potential developmental effects and otherwise is listed as “not available”). The U.S. Centers for Disease Control was able to find only one study on MCHM’s health effects – a proprietary study from manufacturer Eastman, conducted in 1990, that was not published in a peer-reviewed journal.

Federal and state officials only estimated a safe level of MCHM in water after the spill, using the Eastman study. That level, 1 part per million, is an “extremely conservative number,” a spokesperson for the U.S. Agency for Toxic Substances and Disease Registry told the Gazette. That figure indicates that officials and scientists think MCHM is much less dangerous than some more commonly known chemical contaminants – by comparison, the EPA threshold for arsenic in drinking water is .01 parts per million, while the maximum amount of mercury allowed is .002 parts per million.

The lack of information on MCHM highlights a much larger problem, Denison and McPartland say. It’s one of around 62,000 chemicals never tested by the EPA, because they were already in use when the federal Toxic Substances Control Act was passed in 1976.

MCHM and other chemicals “were simply presumed to be safe, and EPA was given no mandate to determine whether they are actually safe,” Denison and McPartland write. “Even to require testing of these chemicals under TSCA, EPA must first provide evidence that the chemical may pose a risk – a toxic catch-22.”