RESPONSE TO COMMENTARIES ON 0.05 BLOOD ALCOHOL CONCENTRATION (BAC) LIMIT

We appreciate the three commentaries on our paper documenting the effectiveness of lowering the alcohol limit for driving from 0.08 to 0.05 blood alcohol concentration (BAC). Our purpose was to stimulate debate and, from the thoughtful commentaries received, we appear to have been successful. We thank Dr Sheehan [1] for her comments generally supporting the need for a 0.05 law in the United States, given that she is a researcher from a country that has had such a law in place in all Australian states since 1991. We also recognize the importance of the comments of Mr Talpins and Mr Hurley [2,3], both strong safety advocates who have held senior positions with Mothers Against Drunk Driving (MADD). They both raised the typical argument expressed by opponents of the 0.05 law that the risk levels associated with BACs in the 0.05–0.07 range are modest. This is certainly true when 0.05 BAC is compared to risk levels at 0.15 and above. However, what is lost in this argument is that lowering the BAC limit for driving in the United States and abroad has typically affected these high BAC drivers just as much as drivers with low BACs [4–7]. This is one of the reasons that we are recommending the 0.05 BAC limit, because it has been proven to reduce the frequency of high BAC (>0.15) drivers in fatal crashes and serves as a general deterrent to drinking and driving. Lowering the BAC limit sends a message to the public that the law is becoming stricter and enforcement more intensive and, thus, reduces alcohol-related crash frequencies at all BAC levels.

Mr Talpins also expresses concern that lowering the limit to 0.05 would substantially increase arrests and strain enforcement resources. However, there was no significant increase in driving while intoxicated (DWI) arrests when states lowered their limits from 0.10 to 0.08 in the 1990s and up to 2003 [8]. Lowering the BAC limit to 0.05 reduces the proportion of drivers on the roads who are impaired by alcohol, whether they are at 0.05, 0.08, 0.10 or 0.15 and greater [5,6].

Mr Hurley notes that the lowering of the BAC limit from 0.10 to 0.08, in which MADD played a major role, saved 600–800 lives a year and argues that the effect of a 0.05 BAC law would be less. However, one study of the effects of the 0.08 BAC laws in the United States estimated that 0.08 BAC laws prevent 360 deaths per year and estimated that lowering the BAC limit even further to 0.05 would prevent an additional 538 deaths per year [5]. If the effects of lowering the limit from 0.08 to 0.05 in the United States are similar to those in Europe and Australia, we can expect a reduction of approximately 8% in impaired driving fatal crashes [9,10], which would currently translate to 800–900 lives saved annually.

We agree and support all four components of the MADD Campaign to Eliminate Drunk Driving; however, there is no evidence that high visibility enforcement has increased in the United States and no evidence that interlock laws have had a general deterrent effect on impaired driving. The advanced technology for passively detecting impaired drivers can certainly be set for a BAC of 0.05 or greater, and in numerous surveys [11] the public agrees with the statement that people should not drive after two or three drinks (less than 0.05 BAC for most people). Why not add one more evidence-based, proven countermeasure to the Campaign and support lowering the limit to 0.05? That policy will save lives as soon as it is adopted.