The crash risk curves did not differ significantly, indicating that both systems generate valid estimates of the relative crash risk of drivers on the road. A revised evaluation found a somewhat lower, but significant, odds ratio, 1. For most other drug classes, the risk is multiplied by a factor between 2 and Among all the drugs, amphetamines seem to increase the risk the most.
While the crash risk after use of an individual drug is relatively low compared to alcohol, with drug combinations the risk is much higher. These combinations occur often. A recent study in France showed that drivers under the influence of cannabis multiply their risk of being responsible for causing a fatal accident by 1. For cannabis, some correlation was found, but several studies have shown that paradoxically, the risk is somewhat lower often not significantly at higher concentrations Martin et al.
This could be explained by the hysteresis relationship between the concentrations of tetrahydrocannabinol THC in blood or plasma and the effects of cannabis. As a result, the effects are maximal when the concentration is already decreasing. In a driving simulator study, Hartman et al. For medicinal drugs, it is important to distinguish regular therapeutic use, according to prescription, from abuse of these drugs.
This plays a role for benzodiazepines and opioids. Most risk calculations based on epidemiological studies will measure the effects of both, and result in a much higher risk than regular therapeutic use. The prevalence of nonprescribed use is high in some populations. For patients with medical prescriptions, according a French study based on the classification system of medicines, category 2 and 3 see Section 7. Moreover, the fraction of attributable road traffic accidents was 3. The effects of drugs on driving performance can also be studied by means of experimental studies, in which different doses of a certain drug are administered to volunteers, and the effects on performance are measured and compared to a placebo or a positive control.
Recreational drugs can broadly be grouped in three main categories: depressants, stimulants and hallucinogens. Yet, due to certain factors that change their characteristics, some drugs may fall under different categories at different times. For example, even though cannabis is considered a depressant, in high enough doses it can also be a hallucinogen.
The acute and chronic effects of the different drug classes on driving performance, and the effects of combinations with other drugs and alcohol, are given in Table 3. Lack of coordination, sensory disturbances, disorientation, restlessness, lapses of attention, difficulty reacting appropriately to safely control a vehicle, increased risk taking, overconfidence in driving skills, drowsiness or rebound fatigue as the effects wear off. At low concentrations the amphetamines can improve attention etc. Depressant drugs slow down, or depress, the functions of the central nervous system.
In moderate doses, depressants can make one feel relaxed. Because they slow a person down, depressants affect coordination, concentration and judgment. Depressants reduce cognitive and psychomotor skills that are necessary to drive such as motor control, reaction time and accuracy, perception and balance. This makes driving and operating machinery hazardous.
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Some deleterious effects of depressants appear to be additive or even synergistic with those of alcohol, and the combination of both substances results in a prolongation as well as enhancement of their effects. Many studies have already been performed to determine the effects of acute alcohol ingestion on cognitive functions and driving performance. Few experimental studies have investigated the acute effects of heroin in humans.
These substances have a legitimate therapeutic use. For example, a systematic review showed that a depressed driver, treated with an impairing drug such as an antidepressant, is a better driver than an untreated driver Brunnauer et al. Also, sensitivity of neurocognitive tasks to drug effects and their validity to predict fitness to drive were generally unknown. While most studies have focused on the impairing effects of a medication immediately after use, measuring the residual effects a few hours after use e. Prescribing clinicians should compare residual effects of the various hypnotics at different doses and select the one considered most favorable in this respect for the individual patient.
This information should also enable them to inform patients more adequately about the likelihood and duration of residual effects of a specific hypnotic dose Vermeeren, Stimulants speed up or stimulate the central nervous system and can make the users feel more awake, alert or confident Ramaekers, Stimulants cause a decrease in overall driving performance by inducing problems such as incorrect signaling, failing to stop at a red light and slow reaction times.
Amphetamines cause a strong central stimulation and euphoria. The user thinks he can do everything and will take more risks. During the crash phase, the subject feels very tired, unable to combat sleep and depressed.
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Amphetamine can improve some cognitive functions such as divided attention performance and verbal interaction Simons et al. However, tests in driving simulators reveal that the intake of amphetamine causes a decrease in overall simulated driving by inducing problems such as incorrect signaling, failing to stop at a red traffic light, and slowing reaction times.
The desired effects of cocaine are similar to those of the amphetamines, but the onset is slower and the duration is longer. In rested persons, some studies found no effect of the use of cocaine on psychomotor or cognitive skills Hopper et al. Hallucinogenic drugs distort the user's perceptions of reality. The main physical effects of hallucinogenic drugs are dilation of pupils, loss of appetite, increased activity, talking or laughing, jaw clenching, sweating and sometimes stomach cramps or nausea.
The effects of hallucinogens are not easy to predict and the person may behave in ways that appear irrational or bizarre. Psychological effects often depend on the mood of the users and the context of use. In extreme cases, this can result in dangerous behavior that can put the user and others at great risk. Driving while under the influence of hallucinogens is extremely hazardous. A cannabis user feels euphoria, relaxation, and increased social interaction with frequent laughing and experiences changes in perception visual, audible, sensory, or time perception.
In higher concentrations cannabis can also act as an hallucinogen in addition to being a central nervous system depressant. A recent study in the Netherlands showed that cannabis induced impairment does not depend on cannabis use history and indicates that tolerance to impairing effects of cannabis on neurocognitive function is generally absent in frequent users. These data confirm previous suspicions that neurocognitive impairments during cannabis intoxication do occur in infrequent as well as frequent cannabis users.
Previous studies reporting absence of neurocognitive impairment during cannabis intoxication in heavy, daily users employed small samples sizes or failed to measure and control for baseline THC which may have decreased study sensitivity Ramaekers et al. An increasing number of studies has measured the prevalence of NPS in drivers in different countries or present case reports Table 4. Although few studies of the impairing effects of NPS exist, because they have the same mechanism of action as the classical drugs Figure 1 , it seems reasonable to assume that they will also impair driving performance.
Most countries have specific DUID legislation. There is a lack of uniformity in the way in which nations approach the DUID problem. The analysis of drugs in body fluids only provides corroborating evidence as to the cause of the impairment. This kind of legislation is subjective and requires the assessment by a medical doctor or a specially trained police officer.
As a consequence, many of the countries with this kind of legislation experienced difficulties in obtaining convictions. Since the prosecution does not have to prove that the driver was impaired, this kind of legislation facilitates the enforcement process. Zero Tolerance laws make it illegal to drive with any measurable amount of specified drugs in the body. For more than a quarter century, there has been a search for drug blood concentrations that are the equivalent of the 0. Some authors suggested that such equivalents are a mirage, and cannot be determined due to variable drug tolerance, lack of consistent relationships between drug blood concentrations and impairment, innumerable drug combinations and multiple other factors.
Withholding DUID legislation pending the acquisition of such data is tantamount to a plan for inaction with regard to an important and growing public health and safety problem.
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This lack of consensus can be partially attributed to the use of different biological matrices serum in Germany, plasma in Belgium and Luxemburg, and whole blood in most of the other countries and the different consequences of a positive result: for example, in Belgium and France there is a penal sanction that follows a positive result, while in Germany or Australia there is an administrative sanction.
Several European countries e. Most Australian states also perform screening and confirmation in OF. An advisory group developed a system for handling DUI of the most frequently used drugs that lead to increased risk of traffic accidents and legislative concentration limits for impairment of nonalcohol drugs corresponding to a BAC of 0.
Since the available literature regarding the central stimulants did not provide evidence for dose—response effects, limits for graded sanctions were not suggested Vindenes et al. These calculated equivalents can be applied by the courts to meter out sanctions Strand et al. Per se limits are often combined with an impairment approach.
This system combines the advantages of the two legal regulations. For a limited list of drugs, the per se approach allows easy prosecution, and the impairment legislation is used to cover less frequently used drugs and other special cases like combinations, withdrawal, etc.
While some countries have a limited list of drugs, in some other countries the list is much longer e. Steuer et al.
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They conclude that police should think about increasing the number of DUID cases in countries where sanctioning differs between alcohol and alcohol plus drug impaired driving. For a screening at the roadside, OF is the most popular matrix thanks to its relatively short duration of collection and analysis, hygienic aspects and simplicity. However, the reliability of roadside drug testing devices still needs improving. Each country has its own legal limits Tables 5 and 6. Very few if any NPS can be detected by a roadside immunoassay.
Nowadays, confirmation toxicological analyses are rapid, very specific, sensitive, multianalyte and they require a low volume of biological sample. In some countries and jurisdictions, a police officer, if he suspects a DUID, can perform clinical tests. If failed, an examination at the police station by a certified drug recognition expert DRE is made. Behavioral impairment tests such as the Drug Evaluation and Classification Program contain 12 systematic and standardized steps, involving interview, clinical signs and psychomotor tests.
According to the DRUID Project, there is a low correlation between the checklist items and the real presence of drug in the body except for a high concentration or a very recent use Schulze et al. In a recent study on drivers in California, Declues et al.
www.hiphopenation.com/mu-plugins/mahaska/speed-dating-church.php In order to enforce the DUID legislation, there is a need for a rapid and reliable roadside screening test for drugs, similar to an alcohol breathalyzer. This would help police officers to determine which drivers have to provide a blood sample, or to take immediate administrative measures like confiscating the driver's license or impounding the vehicle. Roadside drug detection tests are nearly always immunoassays, which are read visually or by a small electronic reader. Some years ago, urine was used for roadside drug testing because of the availability of reliable point of collection tests.
But for some substances such as cannabis, the metabolites can be detected for a long time after chronic use Verstraete, Consequently, the presence of drugs in urine does not necessarily indicate impairment. Another disadvantage of urine is the necessity of sufficient privacy during the sample collection. In recent years, the interest in the use of OF as biological matrix has increased significantly, as this matrix has some particularly interesting properties.
These requirements can be divided into three main categories: requirements for training of police officers on the use of OF screening devices, requirements for operational use of these devices and requirements for documentation. Equipment to be used by police officers during daily enforcement activities should be accompanied by adequate documentation.