Excessive methanol detected in two Chinese wine products (By Imelda Saad, Channel NewsAsia | Posted: 26 August 2009 2051 hrs).
Summary: Two Chinese wine products (detailed in article) has "excessive" methanol and is being "recalled" by Singapore's Agri-Food and Veterinary Authority (AVA). Symptoms of "excessive" methanol intake described. Consumers warned.
Perfectly good advisory.
Here comes the details and my beef with what ought to have been a news report:
AVA said on Wednesday excessive intake of methanol may cause visual disturbances, nausea, abdominal and muscle pain, dizziness, seizures and coma.
As a precautionary measure, AVA has also instructed the manufacturer to suspend production and recall all its Chinese wine products. Retailers have also been instructed to remove all the products.
Consumers who have bought any of the affected wines are advised to discard them.
First of all, the questions:
1. What is methanol and how is it related to alcohol people drink?
Well, I had to do some digging and this is what I found out -
... It is the simplest alcohol, and is a light, volatile, colourless, flammable, toxic liquid with a distinctive odor that is very similar to but slightly sweeter than ethanol (drinking alcohol) ...
... Methanol is produced naturally in the anaerobic metabolism of many varieties of bacteria, and is ubiquitous in the environment. As a result, there is a small fraction of methanol vapor in the atmosphere. ...
... Because of its toxic properties, methanol is frequently used as a denaturant additive for ethanol manufactured for industrial uses — this addition of methanol economically exempts industrial ethanol from the rather significant 'liquor' taxes that would otherwise be levied as it is the essence of all potable alcoholic beverages. ...
... Because of its similarities to ethanol (the alcohol in beverages), it is difficult to differentiate between the two (such is the case with denatured alcohol). ...
which did not quite cover everything I wanted to know (like "what the hell is this toxic substance doing in excessive amounts in a product meant to be consumed by humans?", so I dug even further:
and finally an abstract from a 2001 paper on the (US) National Institute of Health "Defining a tolerable concentration of methanol in alcoholic drinks." which says:
Methanol, a potent toxicant in humans, occurs naturally at a low level in most alcoholic beverages without causing harm. However, illicit drinks made from "industrial methylated spirits" [5% (v/v) methanol:95% (v/v) ethanol] can cause severe and even fatal illness. Since documentation of a no-adverse-effect level for methanol is nonexistent in the literature a key question, from the public health perspective, is what is the maximum concentration of methanol in an alcoholic drink that an adult human could consume without risking toxicity due to its methanol content? Published information about methanol-intoxicated patients is reviewed and combined with findings in studies in volunteers given small doses of methanol, as well as occupational exposure limits (OELs), to indicate a tolerable ("safe") daily dose of methanol in an adult as 2 g and a toxic dose as 8 g. The simultaneous ingestion of ethanol has no appreciable effect on the proposed "safe" and "toxic" doses when considering exposure over several hours. Thus, assuming that an adult consumes 4 x 25-ml standard measures of a drink containing 40% alcohol by volume over a period of 2 h, the maximum tolerable concentration (MTC) of methanol in such a drink would be 2% (v/v) by volume. However, this value only allows a safety factor of 4 to cover variation in the volume consumed and for the effects of malnutrition (i.e., folate deficiency), ill health and other personal factors (i.e., ethnicity). In contrast, the current EU general limit for naturally occurring methanol of 10 g methanol/l ethanol [which equates to 0.4% (v/v) methanol at 40% alcohol] provides a greater margin of safety.
Which answers the next question, but begs the question - "Just how excessive were the levels of methanol detected in the wines? Could industrial foul play be involved as evidenced in the milk case?"
2. What is an excessive amount of methanol for humans?
Answered by the abstract above, but wikipedia has another answer (which one would have to find out if the answers are consistent):
Methanol is toxic. If ingested, as little as 10ml can cause permanent blindness by destruction of the optic nerve. The usual fatal dose is 100–125 ml (4 fl oz). Toxic effects take hours to start and effective antidotes can often prevent permanent damage.
Surprisingly, ethanol (found in alcoholic drinks) is administered as a way to mitigate the toxic effects of methanol consumption as described in the general article on Alcohol.
An effective treatment to prevent formaldehyde toxicity after methanol ingestion is to administer ethanol. Alcohol dehydrogenase has a higher affinity for ethanol, thus preventing methanol from binding and acting as a substrate. Any remaining methanol will then have time to be excreted through the kidneys. Remaining formaldehyde will be converted to formic acid and excreted.
Perhaps my standards are too high, but those felt like pertinent questions to be answered with some level of detail in (what I deem to be) a proper piece of journalism ... e.g. "Methanol, when consumed, is toxic beyond 10 ml but occurs naturally in alcoholic beverages at X%, AVA found Y% which while not highly dangerous (??) is a cause for concern."
Finally, my ungrateful rant - "advised to throw it away"??!! You mean you are not going to act as a facilitator to get the companies to give me a refund for dangerous crap they just sold me? Am I going to have to privately sue them for any medical fees I incur if I fall sick drinking their wines? What is a consumer to do to get any justice from this?