Has anyone ever tried to find the scientific data which establishes 'safe' drinking levels? You'll be looking for a long time.
Sorry Gill, I am going to have to respond to that one!
It really depends on how you define safety and what your risks are, coupled with the time scale over which you are talking.
For example the obvious safe limit is the drink drive limit. This is the point above which you start to become impaired in your physical reactions to the extent that you are a danger to yourself and other road users. That is one definition of safety.
Another definition of safety might be - damage to health. This is hard to pin down since how do you define health. We know that alcohol actually has a J shaped relationship to cardiovascular risk, in that if you drink a little, this is better for you than drinking nothing, but quickly slides into very damaging if you increase the intake. The bottom of the J is in the region of 30mg per day. Since 1 unit is equivalent to 8mg alcohol this corresponds to approximately 4 units, or 2 pints per day. Before you all rush off for 2 pints however, this relates only to the cardiovascular system, not the liver or the brain. It is extremely difficult, if not impossible, to draw up a risk profile for all organs combined since what is beneficial for some organs may be bad for others. Even a little alcohol can impare cognitive ability by a measureable amount for example.
Looking at the long term, alcohol is quite calorific - approximatey 230 calories per pint. Thus if you drink 2 pints a day to keep your CV system in good health, you are actually taking in 460 calories, or almost 25% of your daily calorific requirement. Over the long term this will have a big impact on weight and hence disease.
You could also define safe as 'increased risk of an event compared to that event not happening in the absence of alcohol'. This would then include all the extraneous factors such as domestic violence, vandalism or even nebulous effects such as getting the munchies after a pint or two or smoking increase - how often have you heard people say 'I only smoke when I go out for a drink?'.
It is not a lack of science that is the problem, nor a lack of scientific agreement, but rather differences in the phrasing of the question - how damaging is alcohol? As I have stated on here before, if alcohol was 'invented' today it would be designated as a class A drug.
Steve.