Reading Twitter and following the posts from last week’s Toxic Carnival last Friday night, it occurred to me that one famous toxic chemical had not been covered, one so ubiquitous that I held a dilute solution of it in my hand while toasting the success of the carnival.
I am of course talking about alcohol. Or to be more precise ethanol.
Various forms of alcoholic beverage have been enjoyed by humankind for millenia – Stone Age jugs have been found that support the notion that fermented drinks were made as early as 10,000 BC. Sura, a beverage brewed from rice meal, wheat, sugar cane, grapes, and other fruits, was made in ancient India (a favorite of Indra), while the first beer was brewed in ancient Egypt. A common thread from many of the ancient civilizations was that consuming alcohol was blessed by the gods but excessive drinking (to the point of drunkenness) was frowned upon. This idea was carried through into medieval times and even the Puritans brought more beer than water with them to the modern world, a fact that rather clashes with our modern view of what being a Puritan meant.
The principal reason for this was that drinking beer or wine was safer than drinking water. To make beer, a wort is made with boiling water, which sanitizes the water and as long as it is sealed up, remains free of infection once turned into beer (with the addition of hops also helping to preserve the beer). Drinking water was not usually boiled as a rule and was obtained from places that mixed with sewage or other potential forms of infection. Thus, drinking water was dangerous, while drinking beer was safe. More than that, Bavarian monks brewed their doppelbock beer to sustain then during the Lent fast.
But ethanol is not just a recreational and medicinal delight. As a wise philosopher once said:
Wine is fine but whiskey’s quicker
Suicide is slow with liquor.
Ethanol is in fact toxic, with an LD50 in rats of around 10g/kg. The toxicity comes principally from the metabolism of the ethanol via oxidation to the aldehyde (acetaldehyde) and then the acid (acetic acid). Interestingly, the chemical neighbors of ethanol (methanol, n-propanol, isopropanol) are all more toxic all due to the same mechanism, with methanol most toxic (and also the least sedative effect, so it doesn’t even make you drunk first!). Contamination by some of these longer chain alcohols can contribute to an increased hangover from some alcoholic beverages.
But ethanol itself has a number of toxic effects. It is a central nervous system depressant, which initially causes effects in the cortex, hippocampus and nucleus accumbens parts of the brain which are responsible for thinking and pleasure. It causes sleep disruption (lack of REM sleep especially). The lowering of inhibitions and critical thinking also can place the person (or surroundings) in danger due to a lack of good judgment. High acute doses of alcohol result in nausea, depressed heart rate and respiration, coma and possibly death by alcohol poisoning.
It also has quite severe long term effects, with its addictive qualities being a major factor. Alcoholism, cardiovascular problems and alcoholic liver disease are just some of the major problems resulting from chronic exposure. Liver disease in particular has been seen as an alcohol problem, with the graph below showing the relative change in the rates of various disease states compared to 1971. Liver disease (primarily due to alcoholic liver disease) is by far the worst.
So enjoy the post Toxic Carnival party, but perhaps enjoy in moderation.