Alcohol and drugs are dangerous "passengers"

12 May 2022 The Human Factor

On the topic of high-risk behavior, driving under the influence of alcohol is a major problem. In addition to high speed, alcohol is one of the biggest sources of danger on the roads around the world. Alcohol, without a doubt, makes people feel more relaxed, lifts the mood, and is considered to be a type of “social lubricant” at parties, public celebrations, or in clubs. This is the reason why alcohol is so popular among young drivers. For many young people, having one more drink while enjoying time with friends is just part of socializing. But alcohol also clouds the senses and has a dampening effect on the ability to control and maintain a critical perspective on one’s actions, causing one to stay longer at a party than intended, becoming more and more reckless with each glass, and ending up driving the short distance home after all. Drink driving occurs mainly on known stretches of road that are less than ten kilometers long and that one has driven along many times before.

Countless studies and reviews have shown that drivers who have committed alcohol-related offenses differ from drivers who have not in terms of socio-demographics, performance and personality factors, as well as how much importance alcohol has for their individual lifestyle. The risk of drink driving in road traffic increases with regular and especially excessive consumption and correspondingly marked drinking habits, with high acceptance of this kind of drinking culture, with a complaisant attitude to drinking and driving, with a reduced ability to realistically judge what constitutes an illegal blood alcohol concentration level, with a lack of understanding of how alcohol impairs one’s performance abilities, and, in particular, with a high alcohol tolerance level.


The latter is characterized through the respective person needing to consume more and more alcohol to achieve the same effects. This means that the person will not register an alcohol level of 0.05 BAC as having an impairing effect, for example. However, it has been proven that alcohol has an effect after 0.02 BAC, which becomes increasingly pronounced the more alcohol is consumed. Alcohol affects almost all cognitive performance areas, such as reaction speed, perception, performance monitoring, executive functions, as well as evaluation processes, including the willingness to take risks. It has been shown, for example, that the basic divided attention skills required for driving a vehicle are already impaired below 0.03 BAC. The risk of having an accident increases exponentially from 0.05 BAC.


Germany already introduced BAC limits back in 1953, which were supplemented with penalties and, later on, with monitoring and rehabilitation measures. Back then, the German Federal Court set a limit of 0.15 BAC as constituting an administrative offense. This value was lowered in 1973 to 0.08 BAC and in 2001 to 0.05 BAC. Drivers who are caught posing a traffic hazard with a 0.03 BAC or higher blood alcohol level (e.g. an accident) or who are caught driving with a 0.11 BAC or above, even if they do not exhibit any dangerous driving, are considered not fit to drive. This type of criminal offense is penalized through having one’s driver’s license withdrawn, as well as a fine or a jail sentence. From 0.16 BAC, or with at least two administrative offenses from driving with at least 0.05 BAC, motorists must undergo a medical and psychological evaluation. The aim of this review is to assess whether the driver is likely to continue posing a high risk of drink driving, or will pose such a risk in future.
In 2007, Germany introduced a total ban on drinking before driving for novice drivers. If such an administrative offense is registered for drivers under the age of 21 or novice drivers during the first two years after passing their test, support measures are put in place, for example retraining sessions and penalties, including an extension of the probationary period by a further two years. An evaluation study conducted by the BASt from 2010 was able to show that, during the period after the law was changed, the number of alcohol-related offenses registered for young people under the age of 21 declined above average by 17 percent compared to the period before the change was introduced. For drivers over the age of 21, the decline was just 2.5 percent. The number of young drivers involved in an accident who had a blood alcohol level of at least 0.03 BAC reduced by 15 percent. In the target group of novice drivers, there was also a high acceptance (95 percent) of the zero BAC rule.
The zero BAC rule also applies for novice drivers in several other countries, including almost all states in the USA, as well as in Canada, Australia, Italy, Romania, the Czech Republic, and Switzerland. In many other countries, such as France, Greece, the Netherlands, Poland, Portugal, and Sweden, the limit is set at 0.02 BAC.
A 2020 study from the BASt found that novice drivers who have been affected by the alcohol ban rule since 2007 are also more likely not to get behind the wheel after drinking alcohol in later years. The study analyzed the official accident statistics and fitness to drive register of the German Federal Motor Transport Authority. The study shows that drivers who were subject to a total alcohol ban behind the wheel when they were novice drivers are also less frequently involved in alcohol-related accidents and traffic offenses in later years. Furthermore, compared to the previous survey, the acceptance of the alcohol ban had also further increased, reaching 98.3 percent. This proves that “training” people to accept an alcohol ban from the outset has a positive impact in later years.
In view of the above-outlined consequences of drink driving, many young people now think: “I’ll just leave the car and take my bicycle if I want to drink.” In a 2008 household survey conducted by the University of Münster in North Rhine-Westphalia, 204 out of 591 people (34.5 percent) stated that they used their bicycle “in order to be able to drink alcohol.” Among the 16 to 29-year-olds surveyed, more than half (52.9 percent) agreed with this statement. This suggests that, in particular among young adults, drink driving on a bicycle is not a rarity, and that the dangers of this are underestimated and permissive attitudes encourage such behavior. However, even riding a bicycle on the road after drinking in Germany can constitute an offense. From 0.16 BAC on a bicycle, the rider might have to undergo a fitness-to-drive test in the form of a medical and psychological review, which, if failed, could also result in them losing their driver’s license.



In addition to alcohol, the use of drugs such as cannabis when driving is increasingly posing a problem. International studies show that the extent to which a person consumes cannabis correlates with driving under the influence of this substance and risky driving behavior. There are a number of sociodemographic traits that have been proven to be strongly linked to driving after cannabis consumption – for example young men between the ages of 20 and 25 who had learning difficulties in school (evident from poor academic performance and truancy in school), coming from a single-parent family, or having previously committed several traffic offenses. The main psychosocial factors that can help predict whether someone will drive under the influence of cannabis include a poor state of health, sensation-seeking tendencies, a poor ability to exercise self-control, a personality with a high affinity to risk, as well as aggressive tendencies. All of these are personality traits also exhibited by motorists who commit alcohol-related offenses, unlike those who do not.
For Germany, there are not yet any official statistics on accident numbers, criminal offenses, or administrative offenses in connection with cannabis. For this reason, extracts from available datasets have had to suffice. Out of 1,487 blood samples taken following traffic checks in 2014 in the south and west of Saxony, 39 percent were found to contain cannabis. During the mandated blood tests as part of the medical review for gathering evidence, substance-related behavioral problems and uncertainties could only be established to a limited extent and only rarely. The results are in the low two-figure percentage range – for example problems when walking straight ahead 16.2 percent, turning around 16.5 percent, finger-to-finger test 11.1 percent, finger-to-nose test 10.0 percent, and speech 6.1 percent.
As various studies show, cannabis consumption begins between the ages of 13 and 14 with consumption rates monotonically increasing up to 19 years of age. The highest risk period for firsttime consumption, i.e., the age range when most cannabis users start using cannabis, is between 16 and 18. However, starting drug consumption from an early age (under 15) is considered a significant risk factor for causing later health, social, and emotional disorders, as the physical development of teenagers is not complete at this stage and the drugs seriously disrupt the psychosocial maturation process during puberty. The following factors, among others, play a role in causing young people to continue with their drug consumption beyond the initial try-out stage: anticipated effects, encouragement through social ties to peer group, observing positive effects of drug consumption in others, as well as having experienced subjectively positive pharmacological effects of the psychoactive substance. These experiences cause the development of states such as excitation or calm, relaxation, euphoria, or experiences being intoxicated, which can encourage future cannabis consumption and maintain it on a continual basis.
The consequences of chronic cannabis consumption are multifaceted and can affect people’s willingness and ability to perform. It can impair all of the same cognitive processes that are affected after acute intoxication: concentration, attention level, response capacity, short-term memory and working memory, psychomotor skills/abilities, as well as perception of time and space. In terms of performance willingness, apathy as well as loss of drive, motivation and interest have a negative impact on a person’s cognitive ability to control their actions, and thus on the execution of the driving task.
On the basis of unknown individual genetic dispositions, cannabis can also trigger psychological problems, such as anxiety, depression, or hallucinations, through to fully formed psychiatric disorders, such as mania or a psychotic illness. For this reason, there are certainly good reasons for setting the limit for tetrahydrocannabinol (THC) consumption as low as possible. In Germany for example, the limit is 1.0 nanograms per milliliter of blood serum, which currently constitutes the threshold for an administrative offense. It also marks the point at which a person’s fitness to drive a motor vehicle is called into question and requires evaluation, as it is not possible to exclude for certain the possibility of driving safety being impaired.
By way of comparison, in Europe several countries such as France, Great Britain, the Netherlands, Norway, Portugal, Slovenia, Spain, Sweden, and the Czech Republic have also set THC thresholds. These thresholds range quite substantially between 0.0 and 6.0 nanograms per milliliter of blood serum. The limits set in the states of the USA also vary considerably, ranging between 0 nanograms per milliliters of blood serum, such as in Arizona, Georgia, and Virginia, and 10 nanograms in Maine and Washington state.