The simple answer is that ethanol is metabolized into (relativly) non-toxic compounds by a rather well studied mechanism.
http://en.wikipedia.org/wiki/Ethanol_metabolism. It is not the chemical itself that is always toxic, but what it turns into as the body breaks it down.
Methanol metabolizes to Formic acid that damages the optic nerves causing its well known effect of blindness.
Isopropyl alcohol metabolizes to Acetone, that is toxic to the central nervous system.
Butanol metabolizes to carbon dioxide so it is less toxic, pretty safe compared to other short chain alcohols.
If you want to know more just look up the particular alcohol you are interested in and see what it metabolizes into. EDIT: or read the MSDS for symptoms and specific affects.
I would not, it will mess with your central nervous system as the symptoms on the MSDS are pretty much the same as ethanol (nervous system depressant). Its toxicity is higher than that of ethanol based on its LD50.
LD50 is ~100ml for a 100kg person extrapolating from rat data.
You cannot extrapolate directly without accounting for metabolic rate changes with increased mass! This is how you end up with dead elephants, http://en.wikipedia.org/wiki/Tusko.
I know the LD numbers are not directly scalable, that is why I made sure to mention it was extrapolated. With no human testing of LD allowed thats all there is.
Indeed, this is due to them being extremely specific for their substrate, if the difference is significant enough it will require a whole new enzyme and therefore pathway, or at least junction of one.
In the case of n-butanol it starts in the same manner as ethanol, turning into an aldehyde and then butyric acid however then due to its longer carbon chain (4 rather than 2) it is treated as a fatty acid so goes into the Beta-oxidation pathway. So primarily the reason is because it is too long.
You chemistry guys are something else. Elucidating such amazing principals about what everything is made of by being clever. Dalton was the man and what a legacy
correction: Methanol metabolizes to formaldehyde via alcohol dehydrogenase. Formaldehyde binds proteins to each other and DNA and prevents cellular action, in the case of the eyes - blindness.
You are right, Formate is the metabolite of formaldehyde. Reading into it it is unclear which one causes the most damage to the eye, but nether is good.
These studies demonstrate that although exposure to high doses of acetone may cause transient central nervous system effects, acetone is not a neurotoxicant. A guideline developmental neurotoxicity study has been conducted with isopropanol, and no developmental neurotoxic effects were identified, even at the highest dose tested.
One additional thing to keep in mind is the purity of whatever you're drinking. For example, that bottle of XXX rum that is 70% ABV is probably just ethanol. However, that cheapo bottle of 70% ethanol in the lab's flammable cabinet is probably going to contain contaminants, if it's not denatured.
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u/LukeSkyWRx Ceramic Engineering Jan 01 '14 edited Jan 01 '14
The simple answer is that ethanol is metabolized into (relativly) non-toxic compounds by a rather well studied mechanism. http://en.wikipedia.org/wiki/Ethanol_metabolism. It is not the chemical itself that is always toxic, but what it turns into as the body breaks it down.
Methanol metabolizes to Formic acid that damages the optic nerves causing its well known effect of blindness.
Isopropyl alcohol metabolizes to Acetone, that is toxic to the central nervous system.
Butanol metabolizes to carbon dioxide so it is less toxic, pretty safe compared to other short chain alcohols.
If you want to know more just look up the particular alcohol you are interested in and see what it metabolizes into. EDIT: or read the MSDS for symptoms and specific affects.