MALICIOUS METHANOL WRITTEN BY PAUL HUGHES, PH.D.
TO REDUCE THE RISK OF METHANOLRELATED TOXICITY, IT IS IMPORTANT TO KNOW WHERE IT COMES FROM.
percent (v/v) is also s any chemist will know, the term “alcohol” is technically equivalent to 3500 ml/hl. ambiguous, representing a homologous series of compounds These units are based on a that bear the –OH functional group. Of course, for spirits producers ratio of volumes, but sometimes the main focus is on ethanol, so we tend to use the word alcohol the quantity of methanol is as a direct synonym for ethanol. However other alcohols are very expressed by weight, such as g/ common, if not ubiquitous, in spirits, being derived variously lpa. As the density of methanol from raw materials and during fermentation. is 0.792 g/ml, a concentration Ethanol bears two carbon atoms, C2 H5 OH, and in terms of say, 1 ml/lpa ≃ 0.8 g/lpa. It is of human health it is relatively benign. However its smaller therefore essential that the units are relation, methanol (CH3 OH) is altogether a different story. stated unambiguously when quoting Also known as methyl alcohol or wood alcohol, methanol methanol concentrations. For the is infamous for its toxicity. Indeed there seem to be purposes of this article I will generally keep with the units of an increasing number of methanol poisoning cases, with the World ml/lpa. Health Organization (WHO) citing outbreaks across Africa, Europe To reduce the risk of methanol-related toxicity, it is important and Asia with between 20 – 800 victims, and in some cases fatality to know where it comes from. The traditional hardware store rates of over 30 percent. It is not all that easy to spot methanol solvent methylated spirit, or meths, is mainly composed of ethanol toxicity either, having initial symptoms that closely mimic ethanol to which methanol (typically around 5 percent (v/v) or 50 ml/lpa) intoxication. However, the subsequent oxidation of methanol has been added. This is to make the ethanol (or “spirit”) unfit for first to formaldehyde and then to formic acid can have severe human consumption and exempt it from excise duty. Occasionally health consequences. The list of potential symptoms is diverse, though, there are reports of consumption of methylated spirit, either including temporary loss of vision, blindness, unconsciousness, by accident or due to it being used by unscrupulous individuals to headache, weakness, dizziness, breathing difficulties, produce low-cost counterfeit products. This can be immensely damaging abdominal pains, nausea, diarrhea and vomiting. Treatment to a brand. For instance, if someone drinks a product that is ostensibly a of suspected methanol poisoning is by administering either famous global spirit brand and finds themselves in the hospital (or worse) ethanol or a drug known as fomepizole (4-methylpyrazole). after even modest consumption, the brand is at risk, even if it is clear that Both slow or inhibit the conversion of methanol into what was consumed was not the real spirit. By way of example, it is worth oxidized toxic metabolites, allowing methanol to be noting that the Scotch Whisky Association takes the issue of counterfeiting cleared by the liver. very seriously and employ a full-time legal team to chase down potential The concentration of methanol in ethanol (or other cases of counterfeiting and other illegal activities that affect the global Scotch liquids) can be presented with a bewildering array of whisky market. units. For instance in the U.S., the FDA set a limit of However, methanol is also a natural product of fermentation, arising naturally 0.35 percent (v/v), which is equivalent to 3.5 ml/liter from the yeast, fungal or bacterial fermentation of a wide range of substrates, of pure alcohol (lpa), but often the volume of reference including most if not all fruits, as well as potatoes and agave. The main culprit is not a liter but a hectoliter (hl; 100 liters), so 0.35
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