It is difficult, if not impossible, to argue against the scientific evidence behind the Scottish Government’s decision to lower the drink driving limits. With effect from 5 December 2014, the maximum limit is 22 microgrammes of alcohol in 100 millilitres of breath (reduced from 35). Expressed in blood alcohol content (BAC) figures, which are more commonly used in scientific papers, the limit is 50 milligrams of alcohol per 100 millilitres of blood (0.05%), reduced from 80 milligrams. Initial tests, at roadside and in police stations, are measured using the breath test, followed up by a more accurate analysis based on a sample of blood or urine. This looks like a reduction of 37%; however, with the old limits the Crown Office had directed that no one should be prosecuted with a breath reading below 40. That leeway will no longer be applied, meaning that the actual reduction is one of about 50%.

Drink driving convictions in Scotland fell from 11,871 in 1980 to 5281 in 2011. That is still a very high figure, and one can only speculate at the numbers of drivers whose breach of the law goes undetected. Supporters of the change pointed out that the UK is one of the few countries in Europe with the BAC at 0.08% as opposed to 0.05%. More relevantly there is clear scientific research showing that even with a BAC as low as 0.02% one’s judgment is slightly impaired, with a decline in visual functions and a decline in the ability to multi task. At 0.05% there is reduced coordination and a lowering of inhibitions. This can encourage a more reckless style of driving and reduced response times in emergency situations. Science supports the change.

But where science is irrelevant is in the imposition of penalty, which will remain a mandatory 12 month ban. This apparently is not a devolved matter. A BAC of 0.05% will get you a one month ban in Germany and 6 penalty points in France, with suspension optional. The statisticians do not tell us how many accidents there have been where the driver has been recorded with a smaller, but legal, amount of alcohol. Undoubtedly there will be some hard cases where people are caught out the next morning. It is unfortunate that a degree of proportionality in sentencing was not brought in at the same time.

Scientists have also been busy in the overprovision debate. This article is written in the week where an existing Sainsbury’s store in Edinburgh was refused permission to add two extra chill cabinets to its existing alcohol display. This is a topic close to the heart of the health lobby. October saw the publication of a report entitled Alcohol-related illness and death in Scottish neighbourhoods: is there a relationship with the number of alcohol outlets? Commissioned by Alcohol Focus Scotland it was produced by CRESH, Centres for Research on Environment, Society and Health in Edinburgh and Glasgow. It is a very short report, extending to ten pages plus seven pages of appendices. It concludes that there are large variations in numbers of alcohol outlets in Scotland. It has two other key messages. These are, (1) Across the whole of Scotland, neighbourhoods with higher numbers of alcohol outlets had significantly higher alcohol-related death rates, and (2) Across the whole of Scotland, alcohol-related hospitalisation rates were significantly higher in neighbourhoods with the most alcohol outlets.

There are dangers, however, in relying solely on an executive summary. Criticism of such surveys in the past has been that causal links have not been established. If one delves into the detail of the CRESH report, one sees that this remains the case. The authors concede, our outlet availability measures were a relatively crude way of measuring the actual availability of alcohol in a neighbourhood. We should caution that our study was cross-sectional – it looked at a single point in time – hence while it suggested significant associations between outlet availability and alcohol-related harm we cannot conclude that the relationship is causal. Further analyses over time will be required to establish whether the links are causal, but currently alcohol outlet data for Scotland are only available for a single point in time.

 This is a debate to be continued.

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