What Do We Know About 4-Methylcyclohexane Methanol?

Yesterday, a coal processing chemical called 4-methylcyclohexane methanol spilled into the Elk River in West Virginia, leading to a state of emergency and an advisory against using tap water for 300,000 people in 9 counties. The spill was discovered only because of a licorice-like odor discovered by West Virginia American Water Company (no relation). The company who seems to have spilled the chemical, Freedom Industries, never reported the incident themselves.

Until yesterday, most of us had never heard of 4-methylcyclohexane methanol. Rather than focus on the spill itself, which is going to be well covered by larger news agencies, we decided to spend our post this morning concentrating on the chemical itself: What we know, and perhaps more importantly, what we don’t know, about this compound and its particular role in the process of extracting and burning coal.


4-methylcyclohexane methanol has the chemical formula C8H160. At standard room temperature and pressure, it is a colorless liquid. It is very water soluble, which means it will not form a sheen on top of water like oil, but rather mix into the water column.

coalfrothPictured: the top of a coal frothing vat, where excess minerals are removed from coal to clean it before going to market.

Industrial Uses

4-methylcyclohexane methanol is used in the froth flotation of cleaning coal, especially so-called “coking” coal. Froth flotation is a process used in many sorts of mining to separate hydrophilic (water-attracting) compounds from hydrophobic (water-repelling) ones. In the coal industry specifically, frothing is used to separate coal from ash-forming minerals. According to a story on National Geographic’s site today, this particular chemical is used at about 20 to 25 percent of coal processing plants in West Virginia.

Health Effects

Most sources list the chemical as primarily an irritant rather than a toxin. But according to a peer-reviewed handbook of chemical carcinogens cited by the National Institutes of Health, the chemical’s health effects include:

“Irritates the eyes and the skin. High levels of the vapor may cause irritation of eyes and upper respiratory tract. Repeated or prolonged exposure can cause headaches, irritation of the eyes, nose, and throat, and can also cause a skin rash. High exposures from skin contact or inhalation may cause damage to the heart, liver, kidneys, and lungs, and may result in death.”

But what we don’t know about this chemical is somewhat staggering, considering its use in a widespread industry like coal and the apparent proximity of at least some processing plants using it to important bodies of water like the Elk River. TCI America has a file for most industrial chemicals, listing their uses and hazards. Here are some of the less-than-helpful metrics on 4-methylcyclohexane methanol:

Carcinogenic Effects: Not Available
Developmental Toxicity: Not Available
Auto-ignition and Flammable Limits: Not Available
Volatility, Odor, and Taste: Not Available (though we now know something about the odor)
Solubility: Not Available (though experts have today weighed in saying it is very water soluble)

In short, like so many industrial chemicals, we don’t know nearly enough about 4-methylcyclohexane methanol. One of the reporters for the Charleston Gazzette covering the spill, Ken Ward Jr., said it well on Twitter:

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