Drug Driving

A new law has come into effect that means police officers can now test for, and prosecute, drug diving offences.  ACPO have welcomed the developments  as all of us should really.

The sky news report inevitably raises the idea of zero tolerance, of which I have spoken before.  This got me thinking about one particular drug, cannabis.  If this policy is to be truly a zero tolerance policy, which I seriously doubt for most police force areas, then I have been thinking about the dangers of passive smoking.

Now many will already be thinking  'this doesn't apply to me' I'm a respectable person who doesn't know anyone who smokes cannabis, and perhaps for some this is true.  However, many of us though have been walking down the street and all of a sudden an 'interesting smell' (makes me think of very sweet garlic combined with basil, how middle class!) assaults our nostrils.  Perhaps it's a reflection of where I live, but it is not infrequent round my way.  (Indeed a small cannabis factory was closed by police just a few weeks back round the corner from me).

So I do wonder what effect walking past someone who is actively smoking a spliff (or whatever they are called nowadays) would have on my driving ability.  Would it put me over the drug driving limit? how long should I leave it before getting in my car?  (These are all equally valid questions for the drink driving issue when a zero limit is proposed, although obviously one can't passively ingest alcohol!). I have asked a couple of police twitter accounts and the DFT twitter account this morning but haven't received an answer (hardly surprising they probably get such requests daily) so I thought I would do a bit of looking.

There is evidence to suggest that zero tolerance should be adopted when considering the effect even small levels of cannabis can have on driving performance, although the new laws have not adopted this approach.

The regulations prohibit driving with a limit of 2 microgrammes per litre of blood for THC (Active ingredient in cannabis).  According to a study in the Journal of Analytical Toxicology in 1987 high cannabis use in enclosed environments can lead to high THC levels in urine of passive smokers, although as the authors point out it would be quite uncomfortable in such an environment given the level of pot that was likely to be swirling round the room.  With lower exposure (4 passive cigarettes) there was  infrequent positive testing and generally tests were neutral, make of that what one will (inconclusive I would say and unlucky for some in the current context).  Although it is worth pointing out that the subjects in the experiment were still in an un-ventilated room with the smoker

A study in 2011 examining the inhalation of passive cannabis smoke in dutch coffee shops showed that THC was present in saliva above the legal limit (proposed in the current law) in most participants at 40 minutes exposure.  It is worth pointing out in this study that two locations were used, a larger cafe with more smokers, and a smaller one with less smokers, both produced positive results, although it seems that the smaller the environment the higher the THC levels (with lesser active smokers).

A similar study in 2010  also found levels of THC about 2ng/ml (the drug driving legal limit) from passive cannabis inhalation in a dutch coffee shop at 3 hour exposure, although the authors accepted that the study did not note (unlike the 2011 one) how much cannabis was smoked by other users of the coffee shop.

So it would appear that it is possible to be above the legal limit from passive smoking of cannabis, however unless you are friends with some pretty heavy users it is unlikely you will fall foul of the legislation.  I for one am not too worried now about the funny smells in my neighbourhood giving a false positive.

So what have we learned from this?  Firstly the law is not, despite what policy makers may claim or newspapers report, zero tolerance, there is a tolerance of up-to 2 microgrammes per litre of blood.  You are unlikely to be over this level unless you have spent a bit of time in a Dutch coffee shop, caught an immediate flight home and then decided to drive from the airport (perhaps a taxi might be in order).  Alternatively if you know people who are heavy users then please for everyone's sake do not drive and do not let your friends drive.

Secondly I have also learnt that if you want the thrill of cannabis use without actually buying it yourself Dutch coffee shops seem a good place to visit!

Don't Drink Think!

A new survey for the government's THINK! campaign has found that 92% of the British public would be ashamed of drink driving and 91% felt that it was unacceptable to drive drunk.

This is certainly to be welcomed and represents an attitudinal shift that has been going on for some time.  Indeed the number of accidents involving a drunk driver has been decreasing significantly.  In 2012 6,630 accidents involved a drunk driver (a 44% reduction since 2000), 210 of which were fatal accidents (a 53% reduction since 2000).

Drink driving itself may also be said to be reducing based on the number of drivers failing a breath tests, in 2012 11% of all breath tests resulted in either failure or the driver refusing to give a specimen.  Again that proportion is reducing from 20% in 2003 to 11% in 2012.  At the same time there has been an overall increase in the number of breath tests being issued, from 534,285 in 2003 to 682,558 in 2012.  Over the previous ten years there has be an average 3% reduction year on year in the number of breath tests failed or refused, and an average 6% reduction in the number of road accidents caused by drink driving.

The statistics therefore bear out the opinion poll, however, one should be cautious about the findings of the opinion poll.  Unfortunately, I haven't been able to locate an actual copy of the poll results or the questions asked, therefore the methodology used is unknown.  From my own research I can say that one does need to treat with caution peoples attitudes as expressed in an opinion poll, this is especially the case where that poll relates to questions of legality.

I have little doubt that a very large proportion of the public look on drink driving with distaste, however, what I would question is what members of the public understand by the phrase 'drink driving'.  Are the public aware of the legal limits and how this translates into their own drinking practices?  I think that is much more interesting question and one that is difficult to answer using survey research.

If people aren't aware of the legal demand 

In the UK, the alcohol limit for drivers is 80 milligrammes of alcohol per 100 millilitres of blood, 35 microgrammes per 100 millilitres of breath or 107 milligrammes per 100 millilitres of urine

or aren't aware of how this demand translates into glasses, pints and measures, one needs to be suspect of the attitudes as expressed in the THINK! survey.

What I have found in my own research is that in opinion surveys relating to minor laws people are generally motivated to comply with laws but their behaviour suggests otherwise.  A really rather brilliant study by Darely, Carlsmith and Robinson highlights this problem.  Citizens may profess to know what the law is and claim to be affected by it, however frequently the authors found that the public (and judges, lawyers and police officers) have completely misunderstood the actual legal requirements and thus their claims of being influenced by the law are suspect.

Thus I may think drink driving is unacceptable, however, do I think my pint of Stella puts me over the drink drive limit?  I don't know.  Of course the easiest solution is to not drive at all once drinking (a course I always take and so should you!) however, how do I know when it is safe to drive again? Talk to any police officer and they will have multiple stories of the upstanding member of society being arrested for drunk driving because they had drank the previous night.  Is that as unacceptable behaviour as willful disregard of drink driving rules?  I shall leave that to the reader.

These are important questions that need to be asked, and answered, before we can confidently state that drink driving is no longer acceptable at all.  One reason why this is an important question is due to the repeated call to adopt zero tolerance to drink driving (i.e. 0 alcohol in the blood, breath and urine).  With such an approach there is a danger that you don't take the public with you and that the system becomes discredited because it does not target the actual behaviour that we, as society, find unacceptable.

Some may feel that it is unacceptable to drive with any alcohol in the blood, I suspect however that this feeling is not as widespread as current opinion in the THINK! survey suggests.