How we behave when we're drunk
Talking about lowering the blood alcohol limit in New Zealand to 50 milligrams alcohol in 100 millilitres of blood is today’s big story. I’ve been asked by lots of people over the years about how much alcohol drivers have to consume in order to be over the legal limit. Quite rightly, the ESR scientists indicated to the Science Media Centre briefing yesterday that it’s a function of height, weight, gender, food in the stomach (although that’s a contentious issue in England) and type of drink consumed. Thinking in terms of standard drinks is not helpful, particularly for smaller people, because a standard drink doesn’t take these things into account.
I therefore thought I’d review the drink drive blood/breath alcohol levels that I have seen over the years whilst working as an Alcohol Expert Witness (because I’m a scientist and I keep all sorts of data, just in case…).
The average blood alcohol concentration of men (n = approx 400) was 165, more than twice the legal limit of 80. The most common level was 138.
For women (n= approx 100) the average was 184 with the most common concentration being 154.
Overall, although women were less likely to get done for drink driving, they were usually more drunk than the men (although the highest blood alcohol concentration I’ve seen was a man, nearly 320 in blood).
The biggest thing I’ve noticed though is that people who drive at a level between 60 up to about 100 (in blood) are the ones most likely to think that they’re safe to drive. Reducing the drink driving level to 50 won’t change their perceptions. Will lowering the blood alcohol level to 50 increase the numbers of people who get done for drink driving, or will it force people to rethink what they’re drinking? In my opinion, New Zealand is a hard drinking nation and I think a zero alcohol level would be the best way to go.