I have a hard time with "units" and "drinks" and whatever measure is used to give guidance on the number of beers a fella ought to have in a day or a week or a life. Here is what I know so far:
♦ UK - the measure is a "unit" and represents 10 ml of pure ethyl alcohol.
♦ Australia - the measure is a "unit" and represents 12.7 ml of pure ethyl alcohol.
♦ United States - the measure is a "standard drink" which contains 0.6 ounces or 17.744 ml of pure ethyl alcohol.
♦ Canada - the measure is a "standard drink" which contains 17.1 ml of pure ethyl alcohol.
More countries have more measurements here. So, the initial observation is that the measure is all over the place and a bit of a mess. Then you have to consider the recommended number of these arbitrary and confused "standard" measures. In Canada, we are told "women should consume no more than two drinks most days, up to 10 a week, and men should consume no more than three drinks most days, up to 15 a week." Which means for me, a Canadian male, I should consume no more than 51.3 ml a day or 256.3 ml a week. I also hold UK right of abode, however, so genetically if not jurisdictionally I might find myself thinking I should consume no more than 40 ml a day or 210 ml a week. What to do?
Turns out Canada is about as generous as you find in terms of medical health recommendation. But wouldn't it be easier if there simply was "contains X ml of ethyl alcohol" on the label? Abstracting through units, drinks and days or weeks makes it all far less clear than it could be. Then, what is a standard person? New Zealand acknowledges that heavier folk have an easier go of it but it does beg the question of what is the weight of the person whose unit intake is being used as the standard measure? Again, a problem.
So, what if the drinks told you how many ml of ethyl alcohol were in them and then instead of simply ascribing that to men or women you relate it to body weight? If I weigh around 220 lbs or 100 kg, that means you have 100 litres of mass, 60% of which is fluid. Surely there is a formula that takes into account ml of alcohol per litre in the body. Oh, there is? Sure - it's called blood alcohol concentration and it is one way criminality in drunk driving is measured. In Canada, the standard is 80 milligrams of alcohol in 100 millilitres of blood or 0.08. Or 800 milligrams in 1 litre. Or .8 grams in a litre. Or 1.014 ml per litre of blood. Or 60.84 ml per 60 litres of fluid mass in a human body. Does that work?
I am not suggesting that this should determine when drink driving is safe, just when drinking is safe. But if body weight is determinative in the effect of alcohol on drink driving, should it not equally be determinative in safe drinking? My math may be wonky but the principle holds. If I know that at 120 kg, I have a 20% increased capacity than my 100 kg friend then I should be comfortable expecting that the 51.3 ml per day for him is 61.56 ml for me. Then, if a bottle of beer tells me it has 20 ml of ethyl alcohol, I will know I can have three.