On Jan. 9, a leak in a Freedom Industries chemical-storage facility contaminated the Elk River with 4-methylcyclohexane methanol, leaving 300,000 West Virginia residents without tap water for several days. Nearly three months after the spill, researchers have found that the accident continues to affect the water and air quality in the Mountain State.
“Based on our increasing understanding of the chemicals involved in the water crisis, the complexities and implications of the spill keep growing,” said Andrea Dietrich, professor of civil and environmental engineering at Virginia Polytechnic Institute and State University. “People are still afraid to drink the water. Odors persist in schools, residences and businesses. Data are still lacking for the properties of the mixture of chemicals in the crude MCHM that spilled.“
Dietrich and her research team received a National Science Foundation grant to analyze the properties of crude 4-methylcyclohexane methanol, or MCHM, the major component in the chemicals that spilled into the Elk River. MCHM is used in the separation and cleaning of coal products.
As authorities lifted the bans on drinking-water use, Virginia Tech researchers gathered their data and found that West Virginians still were complaining of an odor in their homes and in the environment.
“Like for many contaminants in water, chemicals leave the water and enter the breathing air, so that inhalation becomes a route for human exposure as well as drinking the water,” explained Daniel Gallagher, a faculty member in Virginia Tech’s Via Department of Civil and Environmental Engineering and a member of the research team.
The Virginia Tech researchers pinpointed the concentrations of contaminants in the air by using olfactory gas chromatography, which allows the investigators to independently measure the concentrations and odors of the two isomers found in the 4-methylcyclohexane methanol.
The researchers determined that MCHM “consists of two isomers: a cis and a trans methylcyclohexane methanol,” according to Dietrich.
“The isomers have the same chemical formula but a very slight shape difference that for many isomers can have enormous effects on the physical, chemical and biological properties,” Dietrich explained. “Only the trans isomer has the characteristic licorice-like odor. The cis isomer is significantly less odorous and has different descriptors.”
The researchers determined that the odor-threshold concentration of the trans-isomer is “exceedingly low,” meaning that the odor of MCHM is easily detectable even when the chemical’s concentration in water is more than 100 times lower than the level that CDC considers harmful.
An “important implication of the findings is the critical need to independently measure the concentrations of the cis and the trans isomers, as was done in this study and is being done at the Virginia Tech labs,” Dietrich said. “The licorice odor will be proportional to the amount of the trans isomer, not the total amount of methylcyclohexane methanol. While there may be a tendency to measure ‘total methylcyclohexane methanol,’ this could lead to misleading interpretations.”
Dietrich is an expert on water quality and treatment, as well as its taste and odor assessment. Several years ago, the American Water Works Association and Research Foundation sponsored Dietrich to travel around the country to educate utility staff and managers on how to use sensory analysis to detect changes in water quality. She also is a co-developer of three odor-testing methods for the daily monitoring of raw and untreated water.