Methylated spirits in DIY hand sanitiser: bad?
March 19, 2020 11:31 PM   Subscribe

How bad is it to use methylated spirits (aka metho or meths) as the alcohol in DIY hand sanitiser?

I'm part of a local FB group that is full of people sharing stuff with people who can't get to it because of the current COVID-19 crisis. There are heartwarming posts of people giving away opened packets of nappies/diapers that their kids have grown out of to people who can't buy any right now. But amongst that, people are posting DIY hand sanitiser recipes that include metho.

I started to make an (well-researched) infographic that I can share on FB and repost as needed with all the information, but as I research it online, it's hard to nail down just how bad it is. Help, please?

(PDF) document saying Australian methylated spirits can't contain more than 5% methanol
(PDF) Illegal to drink in the NT
MSDS from a paint company, Wattyl, which includes "rinse if it gets on your skin" (paraphrased)

Wikipedia on methanol toxicity
posted by freethefeet to Health & Fitness (15 answers total)
As bad as if you drank the spirits - poisoning and vision loss can occur through skin absorption of methyl alcohol as well as ingestion (CDC card here).
posted by terretu at 11:52 PM on March 19, 2020 [1 favorite]

Thanks terretu- is this as bad in the 5% version?
posted by freethefeet at 11:59 PM on March 19, 2020

I don't know how effective it is as a virus killer, but I used it to clean laminated signs several times a week in sessions that lasted 10-30 minutes and as far as I know I was not poisoned through my skin. It is best used in a well ventilated area as it can make you feel light headed. Anecdotally, I did not catch most of the viral flus that went round my office.
posted by a humble nudibranch at 12:11 AM on March 20, 2020

I'm a googler rather than a scientist on this topic so I don't have good infographicable data on how bad the 5% kind is, but if one of the companies making it suggests rinsing if you get it on your skin, I can't see why putting 5% meths on your hands and then immediately rinsing them would be superior to just washing them without wiping them with an at least somewhat poisonous substance first (that's not very pithy as a way of persuading people though). Could you play up the "don't do anything that might mean you need surprise medical treatment right now" angle?
posted by terretu at 12:36 AM on March 20, 2020

Wattyl's MSDS lists their metho's denaturing ingredients as 0.25% methyl isobutyl ketone and 66ppm denatonium benzoate; methanol is not listed.

It also lists occupational exposure limits of 1000ppm for ethanol, 50ppm for MIBK. 0.25% of 1000ppm is 2.5ppm, so exposure to Wattyl metho is going to exceed the limit for ethanol way before getting close to the limit for MIBK.

From the toxicology section of that MSDS:
The material is not thought to produce adverse health effects or skin irritation following contact (as classified by EC Directives using animal models). Nevertheless, good hygiene practice requires that exposure be kept to a minimum and that suitable gloves be used in an occupational setting.

Entry into the blood-stream, through, for example, cuts, abrasions or lesions, may produce systemic injury with harmful effects. Examine the skin prior to the use of the material and ensure that any external damage is suitably protected.
Again, given that their metho contains 95% ethanol and only 0.25% MIBK, the well known toxic effects of ethanol are going to be the dominant consideration there.

If people are absolutely determined to indulge in hygiene theatre with alcohol instead of washing them properly with soap and water, I don't think they're going to take a worse hit from Wattyl metho than from, say, cheap vodka. And I can attest from personal experience that the trace amount of denatonium benzoate left behind on my fingers after cleaning a printed circuit board with a swab soaked in metho is an excellent reminder not to put them in my mouth.

Rather than worrying about methanol, it seems to me that the correct message is that if you can't get hand sanitizer, just take the convenience hit and wash them with soap and water instead.
posted by flabdablet at 1:20 AM on March 20, 2020 [2 favorites]

Just use soap. It's better than alcohol at killing Coronavirus. It breaks the outer lipid barrier of the virus and kills it.
posted by MythMaker at 6:08 AM on March 20, 2020 [4 favorites]

And if you're one of those people like my daughter, who has allowed the bastard advertising industry to persuade her that a cake of ordinary cheap hand soap couldn't possibly be any good because it doesn't come in a plastic bottle with a cunning dispenser, dishwashing liquid works too.

No, NOT dishwasher detergent! Last thing the hospitals need right now is having to deal with chemical burns from caustic soda.
posted by flabdablet at 6:36 AM on March 20, 2020 [2 favorites]

I’m a scientist, and anything in the lab that uses even a bit of methanol has to be collected as hazardous waste. And it cannot go down the sink. Plus, we use all our PPE (gloves, goggles, etc.) when working anything that has methanol. You really, really don’t want to do this.
posted by Knowyournuts at 10:06 AM on March 20, 2020 [1 favorite]

Knowyournuts, are you familiar with the 95% ethanol methylated spirits?
posted by freethefeet at 5:07 PM on March 20, 2020

(and to be clear, I know that soap is the best way to wash hands and no I am not making diy sanitiser: I want to have reliable information about it so I can share with others.)
posted by freethefeet at 5:09 PM on March 20, 2020

Yes. Please tell them not to use this on their skin.
posted by Knowyournuts at 5:29 PM on March 20, 2020

I guess it’s hard to say how much exposure is how dangerous. It depends on the dose, and it depends on how often they use it. The ill effects may not show up for a while. If you get organ toxicity later, you might not connect the dots. Right? But the fumes are dangerous and the liquid itself is highly flammable. Hopefully they are not keeping large quantities of it in their households, any more than they would keep oily rags and other fire hazards around.
posted by Knowyournuts at 5:38 PM on March 20, 2020

Not infrequently a new (enthusiastic) user of shellac will get Methanol poisoning from cutting the flakes with alcohol denatured with methanol and then using it in an inadequately ventilated space. So it is definitely possible though in this case probably from inhalation not skin exposure.

Just use soap.

This isn't always possible. EG: it's not uncommon for me to be away from water for hours at a time while still being exposed to the public and everything they touched.
posted by Mitheral at 6:55 PM on March 20, 2020 [2 favorites]

(best one I saw- 'eh they used to use metho on baby's umbilical cord stumps' - no, that was rubbing alcohol, and now not the suggested practice anyway!)
posted by freethefeet at 8:02 PM on March 20, 2020

are you familiar with the 95% ethanol methylated spirits?

If it's 95% ethanol it's pretty likely that the other 5% is mostly water and that something else is used as a denaturant; it's hard to get that last few percent of water out of alcohol and harder still to keep it out.

Encouraging people to check the MSDS for the specific products they propose to expose themselves to is probably your best bet, along with judicious use of phrases like "not medical grade, not even food grade" and "industrial chemicals".

MSDS guidelines are widely understood to err on the side of caution if they're going to err at all, but people who are convinced that their "common sense" makes a MSDS worth taking no notice of are not going to take any notice of you either.

Also the MSDS will tell you whether there actually is methanol in your metho and if so, how much.
posted by flabdablet at 2:16 AM on March 21, 2020 [1 favorite]

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