Cooking with Alcohol

By Jim McVeagh 24/10/2010


The Herald has kicked off it’s “Two Drinks Max” campaign today. Just what we need – more emotional heat and less rationality.

I don’t have any problem with the somewhat simplistic “Two Drinks Max”. If people want to pledge themselves to this; more power to them. However, I do object to the dishonest way the Herald has linked this campaign to it’s demand that the government reduces the blood alcohol limit for driving to 0.05%. These are not the same thing at all. The first is a voluntary pledge that effects only the volunteer. The second is a demand for a law that will make it illegal for any of us to drive with a BAC (Blood Alcohol Concentration) of greater than 0.05%. Unfortunately for the latter, there is no good evidence that someone with a BAC of 0.08% is more of a danger on the road than someone with a BAC of 0.05%. There is evidence that there is increased impairment of judgement and slower reflexes, but that has not been shown to translate into a higher accident rate. That may sound non-intuitive – until you realise that drivers near the 0.08% limit instinctively tend to drive more carefully than a driver with a BAC of 0.05% – unless the driver is very young. There is also significant impairment to driving skills at 0.05% leading to the question of why this arbitrary limit as opposed to 0.08%?

There is also good evidence that countries that have adopted the lower BAC limits have improved their road fatality rates. This is the bulk of the “overwhelming weight of scientific research” that the Herald cites. Unfortunately, this data is actually much more difficult to interpret than the Herald and “the Law Commission, the Ministry of Transport and top police officers” would have you believe. All the countries that lowered their BAC levels to 0.05% did so in conjunction with increase police presence on the roads and a strong public campaign against drink-driving. It is therefore not clear whether the drop in fatalities was due to the campaign, the extra police or due to the drop in BAC.

Proponents of the reduction in BAC point to the fact that New Zealand’s alcohol-related road accident fatality statistics are worse than Australia’s (28 as opposed to 22 per million population). They attribute this to the 0.05% alcohol BAC limit in Australia. However, from the Ministry of Transport’s own website we get this statement:

Another indicator of the prevalence of drink driving is the results from Police breath testing operations. Nationally about 1 in 150 Australian drivers tested exceed the legal limit of BAC 0.05. In contrast, 1 in 85 New Zealand drivers exceed our limit of BAC 0.08. In Victoria the rate is 1 in 314 drivers tested and in Queensland it is 1 in 192 drivers tested.

Did you get that? 1:150 Australian drivers have a BAC exceeding 0.05%. New Zealand has twice that rate exceeding 0.08%. It should be stunningly obvious that the drink-driving problem is not going to be improved by a lower limit, but by a change of culture.

Which brings me back to the Herald’s campaign. It is a pity that they have seen fit to link their campaign to the reduction of the BAC level instead of sticking with their “Two Drinks Max” campaign at face value. A massive campaign to get people to pledge to less alcohol would probably do far more good than dropping the limit. New Zealanders are far too apt to wink at excessive drinking and condone it as laddish behaviour. I have many patients who tell me, without blushing, that they drink a dozen beers on a Saturday night with the boys. Apparently they think this is normal. Most of these people are responsible and would never dream of driving home in that state – but they give legitimacy to it, encouraging less responsible people to drink excessively. These few then go on to create our appalling drink-driving stats. “Two Drinks Max” might go some small way towards mitigating that culture of drunkenness.

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