Indecisive Drink-Driving Policy Allows for Increase of DUI in the Netherlands

Transcription

1 Indecisive Drink-Driving Policy Allows for Increase of DUI in the Netherlands M.P.M. Mathijssen SWOV Institute for Road Safety Research, Leidschendam, The Netherlands. Keywords Alcohol, drugs, policy, risk Abstract Between the mid-1980s and the early 1990s, DUI in the Netherlands decreased strongly: in weekend nights, the proportion of drivers with an illegal BAC (> 0.5 g/l) dropped from 12% in 1983 to 3.9% in This favourable development followed the introduction and extension of random breath testing, facilitated by the introduction of electronic screening devices and evidential breath testing. In recent years, however, DUI has not decreased any further, and even tended to increase. This may have been caused by an indecisive government policy towards drink-driving. After a reorganisation of the Dutch police forces in the first half of the 1990s, traffic law enforcement was given a lower priority than before. The introduction, in 1996, of a mandatory rehabilitation program for severe DUI-offenders was not accompanied by a large-scale publicity campaign. The introduction of a 0.2 g/l BAC limit for novice drivers, originally intended to become effective in 2001, was postponed by approx. 3 years. Furthermore, the formation of special traffic enforcement units in all 25 Dutch police regions, which started in 1999 and should have been completed in 2001, did not in the short term result in a higher enforcement level throughout the country. In weekend nights of 2000, 4.6% of Dutch motorists had an illegal BAC. Finally, results of a case-control study, conducted in 2000/2001, raised questions on the effectiveness of police enforment and rehabilitation programmes in substantially reducing the number of hardcore drinking drivers and the resulting road trauma. Introduction Between 1970 and 1999, SWOV carried out periodic roadside surveys into the alcohol consumption of Dutch motorists during autumn weekend nights (10 pm-4 am). Since 2000, the surveys are being conducted by the Transport Research Centre (AVV) of the Ministry of Transport. The objective of these surveys is to obtain an insight into the patterns of drink-driving and into the effects of countermeasures. In 2000/2001, SWOV, in collaboration with Utrecht University, conducted a case-control study to determine the relative injury risk of psychoactive substance use by motorists. Until then, only rough estimates of the DUI road toll could be made, based on incomplete official statistics. Methods Roadside surveys Since 1991, roadside surveys have been conducted on a yearly basis. In each of the twelve Dutch provinces a varying number of survey areas is selected, dependent on population size of the province. The sample of survey areas is geographically spread over the province and stratified by

2 degree of urbanisation. In each survey area, a police team, instructed and accompanied by a researcher, is performing RBT-activities at four to six consecutive locations, situated along main roads inside built-up area. The frequent change of location is intended to minimize the predictability of the combined survey and enforcement activities with respect to time and place. Motorists are taken at random from moving traffic and breath-tested by means of a Dräger Alcotest 7410 Plus screening device. Since random breath testing by the police is legally admitted in the Netherlands, non-response is virtually non-existent. Police survey teams are equally distributed over Friday and Saturday nights, and random breath testing is performed between 10 pm and 4 am. Each test result, as well as sex and age of the motorist, is entered on a registration form with preprinted date, time and location. In the end, provincial samples are put together, forming one nationwide sample. Since the distribution of observations over the various provinces is not equal to the distribution of the population (as an indicator of traffic volume), the BAC-distribution of the sample is weighted for provincial population size. The sample size has grown from about 3,000 tested motorists in the 1970s to nearly 25,000 in recent years. Data analysis is performed with the log-linear Weighted Poisson Model (1,2). In 1997 and 1998, a random sub-sample of 893 motorists was also urine-tested for a number of licit and illicit drugs, i.e.: (meth)amphetamines, cannabis, cocaine, opiates, methadone, benzodiazepines, barbiturates, and tricyclic antidepressants (3). In addition to the roadside survey, accident data is analyzed, and police co-ordinators of the police teams are interviewed on developments in enforcement levels and tactics. Furthermore, data on publicity campaigns, rehabilitation programmes, medical examinations, and accident data is collected and analyzed. Case-control study From May 2000 until August 2001, a prospective case-control study was conducted in the town of Tilburg and surroundings, covering a population of approximately 350,000 inhabitants in the south of the Netherlands. Cases consisted of seriously injured motorists who were admitted to the emergency department of the Tilburg St. Elisabeth Hospital. Controls consisted of motorists who were taken at random from moving traffic in the Tilburg police district, which covers the catchment area of the St. Elisabeth Hospital. Body fluids (urine or blood) of both cases and controls were tested for the presence of alcohol and the above-mentioned licit and illicit drugs. The relative risk of psychoactive substances was determined by comparing their prevalence in cases with their prevalence in controls. Odds ratios were computed by relating subjects who had been tested positive for a substance or a combination of various substances, to subjects who had been tested negative for all substances. A 5% probability level (p < 0.05) was used for significance. Results Development of drink-driving Between 1970 and 2000, the proportion of drivers with a BAC >0.5 g/l dropped from 15% to 4.5%. Significant reductions of drink-driving in weekend nights could be observed after police enforcement was intensified and/or the perceived risk of apprehension was enhanced (4): - Immediately after the introduction of the legal BAC-limit of 0.5 g/l, in 1974, the proportion of motorists with an illegal BAC dropped sharply, due to a perceived high risk of apprehension. Although this initial effect diminished quickly, a significant and stable 25% reduction of drink-driving could be observed until the mid-1980s. - From 1985 on, drink-driving again decreased rapidly,coinciding with expanding possibilities for random breath testing (RBT) by the police. RBT was facilitated by the introduction of

3 electronic screening devices and the subsequent introduction of evidential breath testing. The share of motorists with an illegal BAC dropped to 3.9% in A temporarily strong reduction of the enforcement level after a reorganization of Dutch police forces, which came into effect in 1992, resulted in an increase of drink-driving. In weekend nights of 1994, 4.9% of motorists had an illegal BAC. Since then, the pre-reorganization enforcement level was more or less restored, and the proportion of illegal BACs stabilized at about 4.5% between 1995 and 2000 (see Figure 1). Figure 1: Development of the proportion of motorists with an illegal BAC, in the Netherlands, in weekend nights, in the period Drink-driving in the Netherlands, in weekend nights, % High-risk groups Based on roadside survey and accident data, relating to weekend nights of 1996 and 1997, SWOV (4) determined the relative accident risk of the various age categories of male motorists (Table 1). Table 1: Relative accident risk of drink-driving by males of various age categories. Age BAC-ditribution in traffic BAC-distribution in injury-accidents Relative risk (odds ratios) <0.5 g/l >0.5 g/l <0.5 g/l >0.5 g/l yrs 96.5% 3.5% 82.0% 18.0% yrs 94.3% 5.7% 79.0% 21.0% yrs 93.8% 6.2% 81.6% 18.4% 3.4 > 50 yrs 95.6% 4.4% 89.4% 10.6% 2.6 all > 18 yrs 94.8% 5.2% 82.2% 17.8% 3.9 The high relative accident risk of drinking young males is reflected by their involvement in alcohol-related accidents. While forming less than 5% of the Dutch population, males of years form nearly a quarter of all alcohol-intoxicated drivers who are involved in serious injuryaccidents.

4 In view of their high relative accident risk, the development of drink-driving by young male motorists is rather disturbing. In the period , an average of 3.1% exceeded the legal BAC-limit; in the period , 3.5%; and in , 4.0%. Survey data of 2000 (5) showed a further increase of drink-driving by young males, to 4.6% (see Figure 2). Figure 2: Development of illegal BACs among young motorists (18-24 years) in the Netherlands, in weekend nights, in the period Illegal BACs among young Dutch motorists, in weekend nights, male 4 female 3 % Another category of motorists with an extremely high injury risk was revealed by a case-control study (6) that SWOV conducted in 2000/2001, in collaboration with the Institute for Pharmaceutical Sciences of Utrecht University. The study was aimed at determining the relationship between the use of various psychoactive substances and road trauma. Results showed a high relative risk rate, of nearly 50, for drivers with a BAC >1.3 g/l, who had been tested negative for other licit or illicit drugs. Their prevalence in moving traffic was 0.3%, against 10.0% in serious injuries. An even much higher risk rate, of more than 400, was found for drivers who had combined a high BAC with the use of illegal drugs; their prevalence in moving traffic was less than 0.1%, against 11.8% in injuries. For BACs between 0.5 en 1.3 g/l, a moderately enhanced relative risk of about 5.5 was found. No enhanced risk could (yet) be assessed for BAC s between 0.2 and 0.5 g/l. The size of the case and control group was too small for age and sex differentiations. The above figures indicate that, between 1970 and 2000, serious injuries caused by drink-driving in the Netherlands, have decreased less than the overall proportion of drivers with an illegal BAC. Furthermore, they indicate that drivers with a BAC >1.3 g/l, while forming only 20% of all drivers with an illegal BAC, are responsible for about 90% of serious injuries caused by drinkdriving. Drink-driving government policy In 1996, administrative sanctions against severe offenders were sharpened, comprising the introduction of a compulsary three-day rehabilitation programme, to be followed at the offenders own expense. Since then, about 8,000 offenders per annum had to follow the programme. An evaluation study, conducted in , could not determine a significant positive effect on repeat drink-driving (7). General deterrence as a result of the rehabiliatation program was

5 prevented by an almost complete lack of publicity. In 1999, special traffic police squads were (re)introduced in 7 of the 25 Dutch police regions. Within three years such squads should have been created in all police regions. In the 2000 roadside survey, no positive effects on drink-driving throughout the Netherlands could yet be established. The proportion of illegal BACs increased slightly, from 4.3% in 1999 to 4.6% in Among young males the proportion increased even stronger, from 4.1% to 4.6% (5,8). In some selected police regions with a newly formed traffic police squad, however, a 10% reduction of drink-driving was observed; in these regions, enforcement activities had clearly been intensified after the introduction of the new squads. Also in 1999, the Dutch government decided to lower the legal BAC-limit for novice drivers to 0.2 g/l, in order to reduce the alcohol-related road toll caused by young (male) drivers. Positive experiences, especially in Austria (9), contributed to the government s decision. On request of the Ministry of Transport, SWOV made an estimate of the effects that could be expected. SWOV estimated that the new limit would result in a reduction of 12 fatalities and 100 serious injuries per annum (10), without any change of the, rather low, enforcement level. The new limit for novice drivers was intended to become effective in 2001, but was delayed by discussions in parliament and society on a 0.2 g/l BAC-limit for all drivers, like in Sweden. Eventually, in 2002, the government reconfirmed its original decision, but introduction is now foreseen not earlier than for Discussion In the period , the proportion of alcohol-related serious injuries in the Netherlands seems to have decreased much less than the proportion of drivers with an illegal BAC. Since about 90% of alcohol-related serious injuries is caused by a very small proportion of drivers with a very high BAC, hardcore drinking drivers deserve special attention in drink-driving policy. The effect of the existing 3-day rehabilitation programme seems to be too limited for bringing about a substantial reduction of this high-risk group (7). Based on the effects of alcolock programmes on repeat drink-driving in the U.S.A. and Canada (11), the Dutch Ministry of Transport is interested in implementing an alcolock programme in the Netherlands (12). A change of the Road Traffic Act is needed, however. Preparations for a change of law have started in 2002; the moment of actual introduction cannot yet be predicted. Another explanation for the still relatively high proportion of alcohol-related serious injuries, is the ever growing number of young male drivers with an illegal BAC. A quicker introduction of a 0.2 g/l BAC-limit for novice drivers might have stopped this unfavourable development. The (re)introduction of special traffic police squads did, nationwide, in 2000 not result in a substantially higher enforcement level. Based on the number of mouthpieces for breathtest screening devices that were sold to the police, it is estimated that about 600,000 drivers were tested at random. This means that only 1 test in 25 inhabitants (or in 15 license holders) was performed. At this low enforcement level, the risk of apprehension for hardcore drinking drivers, who are forming only 0.3% of all drivers, is almost negligible. Consequently, general deterrence effects on hardcore drinking drivers can hardly be expected. This would even be the case, if the RBT-level would be doubled, unless the additional enforcement capacity would focus on highrisk days and hours, especially weekend nights around the closing times of pubs and bars. In that case, doubling the RBT-level would most likely be highly cost-effective, especially if it would be combined with the introduction of a lower legal limit for novice drivers, and of an alcolock programme for hardcore drinking drivers. But so far, Dutch politicians, and public opinion for that matter, seem to weigh the road toll less heavy than the loss of human life by other causes, e.g. illness, disaster or crime. As long as this mentality does not change, enforcement of drink-driving laws will not get the priority it deserves, when it comes to dividing scarce police capacity.

6 References 1. De Leeuw J and Oppe S. Analyse van kruistabellen: loglineaire poisson modellen voor gewogen aantallen. R SWOV, Voorburg, Vogelesang AW. The analysis of weighted poisson data. D SWOV, Leidschendam, Mathijssen MPM. Drug and alcohol use by motorists in the Netherlands, 1997/1998. R SWOV, Leidschendam, Mathijssen MPM. Dutch drink-driving decreases after new policy. In: Mercier-Guyon C (ed.). Alcohol, Drugs and Traffic Safety T97. Proceedings of the 14th International Conference on Alcohol, Drugs and Traffic Safety, Annecy, France. CERMT, Annecy, 1997, pp AVV. Drink-driving in the Netherlands, 1997/ (in Dutch with English summary). Ministry of Transport and Waterways, The Hague, Mathijssen MPM. The effect of the use of alcohol, illicit drugs and psychoactive medicines on the injury risk of motorists (in Dutch with English summary). SWOV, Leidschendam, Nägele R and Vissers J. Gedragseffecten van de EMA. TT Traffic Test bv, Veenendaal, Mathijssen MPM. Drink-driving and police enforcement in the Netherlands (in Dutch with English summary). R SWOV, Leidschendam, Bartl G and Esberger R. Effects of lowering the legal BAC-limit in Austria. In: Laurell & Schlyter (eds.). Alcohol, Drugs and Traffic Safety - T2000. Proceedings of the 15th International Conference on Alcohol, Drugs and Traffic Safety, Stockholm. 10. Mathijssen MPM. Schatting van de effecten van verlaging van de wettelijke limiet voor alcoholgebruik in het verkeer. R SWOV, Leidschendam. 11. Beirness DJ. Best Practices for Alcohol Interlock Programs. Traffic Injury Research Foundation, Ottawa, Bax C (ed.). Alcohol Interlock Implementation in the European Union; Feasibility Study. SWOV, Leidschendam, 2001.