AUDIE CORNISH, HOST:
We're going to focus on the chemical that's caused all this trouble in West Virginia. It's commonly used to clean coal. But as NPR's Elizabeth Shogren reports, it's also something of a mystery.
ELIZABETH SHOGREN, BYLINE: The chemical is called 4-methylcyclohexane methanol, or MCHM. If you've never heard of it, you're in good company. Most chemists and toxicologists haven't either, nor had the water company or emergency responders in West Virginia who had to deal with thousands of gallons of the stuff spilling from a tank and contaminating drinking water.
West Virginia's Secretary of Health and Human Resources, Karen Bowling, says the state relied on advice from the Centers for Disease Control and Prevention.
KAREN BOWLING: There are unknowns, so we have to rely on what is already known about and what's been tested about this particular chemical.
SHOGREN: At the time of the accident, the CDC didn't have a standard for how much of this chemical in water is safe to drink, so they had to come up with one. The agency relied on an animal study that established what was lethal for rats. Vik Kapil is the chief medical officer at the CDC's National Center for Environmental Health.
VIKAS KAPIL: And from that, you would decrease the proposed levels down further and further, taking into account all the uncertainties.
SHOGREN: Kapil acknowledged that there was very little data to go on. West Virginia officials say they also turned to safety information companies must provide on chemicals they possess. Toxicologist Sharon Meyer says it didn't say much.
SHARON MEYER: And the entries were largely data not available, data not available for this particular compound.
SHOGREN: Meyer is an associate professor at University of Louisiana at Monroe. She says she analyzed the compound's structure and saw nothing obvious that should present a concern to people who drank it.
MEYER: I really think that they were not exposed to extreme levels that would cause serious problems. But I don't have the data to definitively say this.
SHOGREN: Arizona State University professor Rolf Halden wasn't surprised that the scientific literature had so little information about MCHM.
ROLF HALDEN: There's 85,000 chemicals in commerce right now in the United States, and we cannot possibly test all the chemicals for all the different properties.
SHOGREN: Halden researches how chemicals move through the environment and people. He used a computer model from the Environmental Protection Agency to calculate how this chemical would behave in the environment. He says it likely would not persist. Half of it would be gone from the water in two weeks and half from the soil in a month. That's because microbes in the soil will likely eat it.
HALDEN: I would not be terribly concerned about long-term contamination of the environment with this chemical.
SHOGREN: Still, the accident shed a light on how little is known about many chemicals. Lawyer Lynn Bergeson specializes in the regulation of toxic chemicals.
LYNN BERGESON: These incidents are very painful for the local residents there in West Virginia. They are embarrassing to federal and state governments that would appear to not have as much information as they would like to be able to report to local residents.
SHOGREN: Bergeson hopes this accident will spark new interest in updating the 40-year old law that governs toxic chemicals. Elizabeth Shogren, NPR News, Washington.