A significant number of traffic accidents are caused because the road users are under the influence of medication. The biggest culprits are the so-called benzodiazepines, a group of medications that are prescribed as sleeping tablets and tranquillizers. Beitske Smink, a toxicologist at the Netherlands Forensic Institute (NFI), investigated the risks of benzodiazepine use in traffic and what method is best for ascertaining whether somebody has taken benzodiazepines. She determined that the saliva test has potential. Smink will be awarded a PhD for her research by the University of Groningen on 17 October 2008.
Benzodiazepines are among the most common medications in the Netherlands. They are not only regularly prescribed, they are often taken for far too long. Smink: ‘They are sleep inducing and a muscle relaxant. These are effects that you do not need in traffic. That’s why they often turn up in accident situations.’ You are not allowed to drive under the influence of substances that can affect your driving ability, but many users ignore this. ‘You get people who can’t sleep taking a tablet in the middle of the night. They then get into their cars as normal the next morning, but the drug is still working.’
Quick results
When people are stopped by the police (for example for bad driving) and alcohol does not play a role, then blood is taken and sent to the NFI. There the blood is tested for benzodiazepines, among other things. However, taking a blood sample is rather complicated and the aim is that as few people as possible go through this procedure needlessly. It would therefore be useful if the police could check quickly whether or not the driver they’ve stopped has been taking benzodiazepines. ‘A breathalyser test, like the one for alcohol, won’t work because benzodiazepines are not detectable in your breath.’
Saliva versus urine
Smink thus investigated whether saliva or urine would be suitable for determining the degree to which someone is under the influence of benzodiazepines. She used various laboratory tests. These tests had to satisfy numerous conditions. Smink: There are many different types of benzodiazepines. A test therefore has to be able to detect about twenty different types of substance.’
In order to compare the presence in saliva and urine with that in blood, Smink had eight volunteers take the tranquillizer oxazepam. Then the results of the saliva and urine tests were compared with the concentration of the substance in the blood. This revealed that the concentration of benzodiazepines in saliva is much lower than in urine. This would imply that saliva is less suitable as a test material, but the concentration in saliva better reflects the concentration in the blood than that in urine does. Saliva tests are thus a better indicator of recent use. An added advantage is that it is easier to take saliva samples than urine samples.
Public information
Saliva tests will not replace the blood tests. Smink: ‘It’s more a preselection process – currently only blood can be legally used as evidence.’ According to Smink, it’s not yet known when the police will introduce saliva tests as a check. ‘It’s up to politicians to decide whether to introduce this or not. Then the police must learn how to use it and the tests also need further research.’ Saliva tests will make checking for benzodiazepines easier, but at the same time the information from care providers to users must be improved, emphasizes Smink. A special publicity campaign on this subject will be launched in the autumn.
Limiting value
Smink also investigated the link between benzodiazepines in the blood and traffic accidents. This is already well established for alcohol, but not yet for benzodiazepines. If the link could be shown, it would then be easier to set a punishable value – just as for alcohol. Currently, during prosecutions, every individual accident has to be shown to have been caused by a driver under the influence of this medication.
Smink studied a large number of files of arrested drivers for this part of her research. Their external phenomena were described as well as the concentration of benzodiazepines in their blood. This revealed a clear link, although it is difficult to set a limiting value on the basis of these results. Smink: ‘More research is needed for that. In addition, it’s up to politicians to decide where they want to set the limit.’
Note for the press
Curriculum Vitae
Beitske Smink (Utrecht, 1966), studied Pharmacy in Utrecht. She worked for a number of years as a pharmacist after graduating in 1992. In 1996 she joined the Netherlands Forensic Institute as a scientific toxicological researcher. She started her PhD research in 2002. The research was conducted at the NFI in cooperation with the University of Groningen, Department of Pharmaceutical Sciences/UMCG and Utrecht University, Department of Pharmaceutical Sciences. The title of her thesis is Benzodiazepines and traffic safety: Forensic, analytical-toxicological and epidemiological aspects of driving under the influence of benzodiazepines
Symposium
Driving under the influence of alcohol, drugs and medication is a hot topic internationally. With an eye to traffic safety and the reduction of the number of traffic accidents, great attention is being paid to this problem. On Thursday 20 November 2008 the Netherlands Forensic Institute, the University of Groningen and Utrecht University will be organizing a symposium where recent research results will be presented and current social developments will be explained.
Further information
From the NFI press officer: Inge Oevering, tel. 070-888 6155
