Scientists at Virginia Tech say a chemical that contaminated the Elk River in West Virginia early this year, is more complex than previously known. A new study may explain why a telltale smell persists, after officials declared the water safe to drink, more than two months ago.
Before the chemical spill January 9th, little was known about something called crude methylcyclohexane methanol or MCHM. Long used as a cleaning agent in the coal industry, 10,000 gallons spilled into the Elk River, contaminating much of the state’s water and leaving it with what many describe as the scent of licorice.
“The smell is present is present at much lower concentrations that what the CDC says people could drink," says Andrea Deitrich, a professor of civil and environmental engineering at Virginia Tech. She led a study that found the human nose can detect MCHM at more than one-hundred times lower than the guideline recommended by the Centers for Disease Control. “The people in West Virginia have been smelling this methylcyclohexane compound for almost two months now. And any type of odor that persists for a long time, is annoying to people.”
Her team began studying the chemical soon after the January ninth spill, with a Rapid Response grant from the National science foundation. But Deitrich an expert in water testing went beyond its scope to find out what was causing the persistent odor. They found the chemical is easily vaporized and that’s what causes what they call the ‘odor threshold’ to be lower than previously thought. They also found that MCHM is actually a two-part molecule and only one of them is responsible for the strong smell.
“And that means, that modeling MCHM as one chemical is the wrong approach because it’s really two chemicals.”
The long term effects of MCHM are not known. Few studies have been done since it was grandfathered in for use under the Toxic Substances Control Act of 1979. But the team’s early research has found that the two forms of MCHM not only have different smell properties, but they also have different chemical properties. They dissolve differently in water and in fat. Dietrich wants to dig deeper and look at how the chemical has moved around the water system.
