On the 9th of January 2014, an accident took place in Charleston, West Virginia; a leak from a tank from Freedom Industries led to the spill of a chemical – 4-methylcyclohexane methanol (MCHM) – into the Elk River.
This raises several important questions: How dangerous is MCHM? Which are the risks associated with it? How can be removed from the river waters?
MCHM: 4-methylcyclohexane methanol
4-methylcyclohexane methanol (MCHM) is a chemical compound; its structural formula can be seen in the picture on the side.
Chemically, it is classified an as an alcohol, due to the presence of an O-H group.
Industrial Use of MCHM
MCHM is employed in industry as a frothing agent; this is a compound which, if put into a liquid, can favour the formation of air bubbles.
Because of this characteristic, MCHM is used in a process to purify coal, i.e. to separate coal powder from other species and/or wastes.
When air is bubbled through water containing the coal dust and MCHM, the MCHM forms bubbles as a froth or foam on the surface of the water.
The fine coal particles stick to the surface of these bubbles, whereas the other wastes do not.
The froth can then be removed from the water, separating coal particles from the wastes. The coal obtained from this process is cleaner and it has higher calorific value.
The Freedom Industry plant in which the leak took place used this process.
Unfortunately, not many data are available on the toxicity of MCHM and the possible effects on both humans and environment. In the MCHM safety sheet, risks such as irritation to the skin, eyes and respiratory system are mentioned; they also recommend avoiding ingestion (eating or drinking) of MCHM.
At the same time, however, it says clearly that the complete “health risks associated with this compound have not been fully determined”. In other words, there is not full knowledge about the long term effects of inhalation of, ingestion of, and exposure to, MCHM.
Virginia Chemical Spill Safety Limit?
MCHM is less dangerous than many other industrial chemicals. In the past, for instance, industry used 2-ethyl ethanol in the coal purification process; this chemical was then eliminated as it is known to be teratogenic (can cause birth defects). No such evidences exist for MCHM.
As for any other chemical, however, the concentration always plays a key role in assessing potential toxicity.
On this point, again, not many data are available. The US Environment Protection Agency (EPA), for instance, does not have a specific limit value for MCHM in drinking waters; in fact they just have a generic limit for foaming agents (0.5 mg/L).
Following this accident, it is likely that science will perform more detailed study on MCHM, and regulators will institute more precise regulations.
Toxic Chemicals: Cleaning the Environment
As safety measure, residents from some West Virginia counties were advised to use drinking/tap water just to flush the toilet but for nothing else (washing, cooking, drinking, etc.). This measure will stay in place until the waters contaminated are cleaned. But how will the cleaning be performed?
Considering the lack of information on MCHM, it is likely that there is not a proper protocol for water cleaning. However, some general principles which are used for cleaning the environment of other chemicals can also be applied here.
Use of Sorbents
One of the most common ways to remove a liquid pollutant from water is to use a solid material which can “sorb” the pollutant. Generally these sorbents work through two possible processes: they can either absorb the liquid by swelling up, or adsorb it onto their surface.
The spill clean-up instructions reported on the MCHM safety state: “Absorb with an inert material”; therefore, absorption is preferable for this chemical.
It is important, however, to absorb just the pollutant – and not the water itself and/or other chemicals dissolved in the water. In this case, MCHM is a non-polar compound, and so not very soluble in water, which is highly polar. Therefore, cleanup crews will absorb the chemical using a material which has a higher affinity for a non-polar compound than for water (a hydrophobic material).
West Virginia Chemical Spill
Although there are many chemicals in use in various industries, we don’t have adequate safety information for all of them. Unfortunately, without studies in place, we many not discover the long-term effects of 4-methylcyclohexane methanol exposure in West Virginia until time has passed.
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