The driving performance is easily impaired as a consequence of the use of alcohol and/or licit and illicit drugs. However, the role of drugs other than alcohol in motor vehicle accidents has not been well established. The objective of this study was to estimate the association between psychoactive drug use and motor vehicle accidents requiring hospitalisation. A prospective observational case-control study was conducted in the Tilburg region of The Netherlands from May 2000 to August 2001. Cases were car or van drivers involved in road crashes needing hospitalisation. Demographic and trauma related data was collected from hospital and ambulance records. Urine and/or blood samples were collected on admission. Controls were drivers recruited at random while driving on public roads. Sampling was conducted by researchers, in close collaboration with the Tilburg police, covering different days of the week and times of the day. Respondents were interviewed and asked for a urine sample. If no urine sample could be collected, a blood sample was requested. All blood and urine samples were tested for alcohol and a number of licit and illicit drugs. The main outcome measures were odds ratios (OR) for injury crash associated with single or multiple use of several drugs by drivers. The risk for road trauma was increased for single use of benzodiazepines (adjusted OR 5.1 (95% Cl: 1.8-14.0)) and alcohol (blood alcohol concentrations of 0.50-0.79 g/l, adjusted OR 5.5 (95% Cl: 1.3-23.2) and >or=0.8 g/l, adjusted OR 15.5 (95% Cl: 7.1-33.9)). High relative risks were estimated for drivers using combinations of drugs (adjusted OR 6.1 (95% Cl: 2.6-14.1)) and those using a combination of drugs and alcohol (OR 112.2 (95% Cl: 14.1-892)). Increased risks, although not statistically significantly, were assessed for drivers using amphetamines, cocaine, or opiates. No increased risk for road trauma was found for drivers exposed to cannabis. The study concludes that drug use, especially alcohol, benzodiazepines and multiple drug use and drug-alcohol combinations, among vehicle drivers increases the risk for a road trauma accident requiring hospitalisation.

Improved laws, enhanced enforcement, and public awareness brought about by citizens' concern, during the 1980s led to dramatic declines in drinking and driving in the industrialized world. The declines included about 50% in Great Britain, 28% in The Netherlands, 28% in Canada, 32% in Australia, 39% in France, 37% in Germany, and 26% in the United States. Some of these declines may be due in part to lifestyle changes, demographic shifts, and economic conditions. In most countries the declines reversed in the early 1990s and drinking and driving began to increase. By the middle of that decade the increases stabilized and the rates of drinking and driving again began to decline. These decreases were much less dramatic than those in the 1980s. Approaching the end of the 1990s and early in the new century, the record has been mixed. Some countries (France and Germany (until 2002)) continued to reduce drinking and driving while in other countries (Canada, the Netherlands, Great Britain, and the United States), there was stagnation and in some cases small increases or even large increase as was the case in Sweden. Complacency and attention to other issues in recent years have been difficult to overcome in some countries. Harmonization of traffic safety laws in the European Union has strengthened laws in some countries but threatens existing strong policies in others. It may be that the major gains have already been made and that additional progress will require a much greater level of scientific knowledge, use of new and emerging technologies, and political and social commitment to put in place proven countermeasures.

Benzodiazepines are the most frequently detected medicinal drugs in drivers. The use of benzodiazepines is associated with an increased road accident risk. In this study, the presence of benzodiazepines detected by liquid chromatography-(tandem) mass spectrometry [LC-MS(-MS)] in oral fluid and urine samples obtained from drivers stopped during a roadside survey was compared. In addition, the sensitivity and selectivity of enzyme multiplied immunoassay technique (EMIT II Plus) relative to LC-MS(-MS) was determined for both matrices. A total number of 1,011 urine samples were collected and screened for benzodiazepines using immunoassay (IA) (EMIT II Plus; cutoff 300 ng/mL). In the IA-positive (n = 25) and a group of randomly selected negative urine samples (n = 79), the presence or absence of benzodiazepines was confirmed by LC-MS-MS after deglucuronidation. The corresponding oral fluid samples (n = 101, 3 samples omitted), were analyzed by LC-MS(-MS) and IA (EMIT II Plus; cutoff 10 ng/mL). The presence of benzodiazepines was demonstrated by LC-MS-(MS) in all IA-positive urine samples, but in only four corresponding oral fluid samples. Concentrations in oral fluid were, one substance excepted, lower than in urine. The sensitivity and specificity of EMIT II Plus were better by using urine as matrix for screening of benzodiazepines than by using oral fluid. The results show that benzodiazepines are detectable in oral fluid. More research has to be done to determine the pharmacokinetic profile of the different benzodiazepines in oral fluid and to study the relationship between dose, concentration (in oral fluid and blood), and impairment.

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The applied methodology for CBA has involved a simplistic behavioural response to enforcement increase and control efficiency. Although this methodology should be developed further, it is clearly indicated that the cost-efficiency of increased law enforcement of drug driving offences is dependent on the baseline situation of drug-use in traffic and on the current level of enforcement, as well as the RR and prevalence of drugs in road traffic.