What is MCHM?

Crude MCHM is a mixture of pure MCHM (4-methylcyclohexylmethanol) and other chemicals (4-(methoxymethyl)cyclohexanemethanol, methyl 4-methylcyclohexanecarboxylate, dimethyl 1,4-cyclohexanedicarboxylate, methanol, and 1,4-cyclohexanedimethanol). Crude MCHM is used in washing coal. It is used as a frothing agent, which means that when air is bubbled through water containing MCHM, the MCHM forms bubbles on the surface. Fine coal particles stick to the MCHM and so can be separated from wastes in the coal.

As this video indicates, MCHM is not highly soluble. This makes it is difficult to remove from the inside of pipes and hot water heaters, as discussed in the video.

MCHM is more dangerous in hot water because more of the MCHM vaporizes into the atmosphere. Eastman Chemical, the manufacturer of crude MCHM, notes in their Material Safety Data Sheet that “at elevated temperatures, vapor may cause irritation of eyes and respiratory tract.”

Very little is known about the toxicity of either pure MCHM or crude MCHM. This site contains all of the (very few) toxicity studies conducted by Eastman, its manufacturer.

MCHM has a half-life in water of approximately two weeks. This means that after two weeks, half of the MCHM will have broken down into other chemicals. Nobody is talking about these other chemicals.