PSA: Toxic Sanitizer

[writerkit]

https://arstechnica.com/science/2020/07/mounting-poisonings-blindness-deaths-as-toxic-hand-sanitizers-flood-market/?fbclid=IwAR0VW7df86MJFVM7NPRroZxlxpShUbjVdlgmq_75rstX4rteGvZA4cGdA_o

The FDA has issued a warning for several sanitizer brands because they're containing methanol, which is toxic.

Seriously, super, incredibly toxic. It breaks down into *formaldehyde*, y'all.

Comments

[squirrelitude]

I think the danger is being blown out of proportion, personally.

As far as I can tell, the main risk is having this around people or pets who might drink it -- a few tablespoons of 80% ethanol probably won't kill a toddler, but the same amount of 80% methanol might.

Estimations of the lethal and exposure doses for representative methanol symptoms in humans: « Methanol penetration is predicted at 2.0 mg/cm2/h » on skin, which the paper describes as "high" but that seems low to me relative to proper usage of hand sanitizer.

If you used 100% methanol hand sanitizer 20 times per day and it stayed in full contact for 10 seconds, and given a surface area for each hand of 425 cm², you'd absorb about 50 mg. I don't know what the toxic threshold is, but that's about 1000th the lethal dose. I *think* this level might be considered borderline, but I'm actually not seeing ready numbers for low-grade toxicity. (The same paper reports a background concentration of about 2 mg/L methanol in urine, for comparison.)

I believe it is more readily absorbed through the respiratory system as fumes than through the skin, but I almost always apply hand sanitizer when I'm out and about, not in a confined space, and I'm not horking the fumes.

More concerning is the carcinogenic potential of formaldehyde, but formaldehyde is already present in food and produced by your own body, and your body has mechanisms for clearing it pretty effectively.

So, personal risk assessment: I'd be OK with having it in the house but I'd want to keep it better locked away than the Everclear (which I bought for use as hand sanitizer). I'd be OK with using it for a few months until I sourced something better, but would not want to use it for years on end. And I would only want to apply it in well-ventilated spaces.

[writerkit]

It's not overblown; it's targeted at the general public, the vast majority of whom are not capable of sitting down and doing the kind of analysis you just did here or consistently maintaining the sort of safety standards you describe. Note that the reason it was discovered in the first place was because there were several deaths and cases of permanent blindness; that argues that your risk assessment here does not apply when applied across larger groups in reality.

[squirrelitude]

The general public doesn't need to do that kind of analysis. I think the FDA's messaging is actually entirely reasonable here: « Methanol, or wood alcohol, is a substance that can be toxic when absorbed through the skin or ingested and can be life-threatening when ingested. » And I don't think the general public need to maintain strict safety standards either -- the FDA says "don't buy these brands", and I agree with that. It's just that I think the risk of ignoring or missing that recommendation are being overblown in the press and social media.

I'm guessing that some of the cases are intentional ingestion by alcoholic adults, similar to https://en.wikipedia.org/wiki/2016_Irkutsk_mass_methanol_poisoning -- but the FDA is being cagey about the nature of the actual incidents, so who knows.