Alcohol and Drugs Foundation of Australia
Drugs and Driving

• BACKGROUND
  
  • The Effects of Drug Use on Driving
    
• ANALYSIS OF VICROADS 1996 STATISTICS
  
• RELATED ISSUES
  
• COMMUNICATION METHODS AND TARGET GROUPINGS
  
• BACKGROUND BIBLIOGRAPHY
  

BACKGROUND

"Drug abuse remains a scourge. It affects every level of our society and no one is immune from the threat of being killed or injured in a crash involving a drug-impaired driver. When drugs are taken and a person drives the likelihood of becoming a road toll statistic increases dramatically." (Road Safety Committee 1,1996,p.vii)

Victorians use drugs for recreational, medical and professional purposes and the drug types used vary widely. This trend in licit and illicit drug use is paralleled in many Western societies and is of increasing concern as a health issue generally and, more specifically, as a road safety concern.

The major drugs of concern in terms of driver impairment are the main drugs of abuse and the common prescription drugs including benzodiazepines (minor tranquillisers), tranquillisers, sedatives, antihistamines, antidepressants, narcotic analgesics and antipsychotics. The use of these in Victoria has been identified in the following manner:

TABLE 1: DRUG USE IN VICTORIA

Note *Less then 1 % - Not asked in 1995 survey (National Drug Strategy Household Survey as cited in Premier's Drug Advisory Council. 1996, P. 12)

While alcohol do most widely used drug there is an increasing awareness of the use of prescription and illicit drugs and the effects they have on the community.

In March 1996, the Victoria Police provided the Inquiry into the Effects of Drugs (Other than Alcohol) on Road Safety in Victoria with the following breakdown of the prevalence of drugs in drivers involved in collisions:

TABLE 2: COMBINED BLOOD SAMPLE ANALYSIS 1993-1995 DRIVERS INVOLVED IN COLLISIONS

(Road Safety Committee 1, 1996, p92)

These statistics highlight the significant overlap between alcohol and drugs and the use of drug combinations. They also highlight that drug use may not only lead to driver fatalities in extreme cases, but may also impair driving factors, for example crash avoidance, which can then result in collisions and injuries, not necessarily death.

In May 1996, Professor Olaf Drummer provided the Inquiry into the Effects of Drugs (Other than Alcohol) on Road Safety in Victoria with a comparison of drugs involved in driver fatalities in two periods - 1990 to 1993 and 1994 to June 1995.

TABLE 3: COMBINED BLOOD SAMPLE ANALYSIS OF DRIVERS INVOLVED IN COLLISIONS (Victorian Data). Comparison of 1990-93 and 1994-mid 1995.

(Road Safety Committee 1, 1996, p. 84)

When these statistics were compared it was found that the incidence of drugs in total driver fatalities had increased from 21.6% to 24.4%. It was also found that the incidence of alcohol had decreased from 32% to 28% and that there was a slight increase in the prevalence of cannabis.

In mid 1997, John Richardson presented updated figures for the prevalence of drugs in driver fatalities at the International Council of Alcohol, Drugs and Traffic Safety Conference. These latest figures show that for the first six months of 1997 drugs were present in 31 % of driver fatalities, alcohol in 28% of cases and that the most commonly found illegal drug was still cannabis.    (Richardson 1997)

TABLE 4: PREVALENCE OF DRUGS IN DRIVER FATALITIES, 1994-95 VICTORIA, NEW SOUTH WALES AND WESTERN AUSTRALIA

(Road Safety Committee 1, 1996, p. 83)

While the driver fatality statistics assist in understanding the impact of drugs on driving, they provide a limited view of the total road crash population, less than one per cent of drivers. Also, the causes of fatal crashes may be different to less severe crashes. Because of these limitations Tables Two and Four are most effective when viewed together.

The Road Safety Committee collated data from New South Wales, Western Australia and South Australia detailing the prevalence of drugs in drug impaired drivers. Using this type of analysis cannabis was again dominant. Apart from the benzodiazepines the incidence of other general prescription drugs was relatively low.

TABLE 5: PREVALENCE OF DRUGS IN DRUG-IMPAIRED DRIVERS

• Sight
• Hearing
• An ability to perceive hazards and identify risk taking behaviour
• Concentration, alertness and reaction time to make decisions
• Physical competence to undertake steering and braking movements
• Accuracy of movements such as steering vehicle within traffic lanes

• Amphetamines and stimulants induce short-term stimulation that increases awareness and confidence and reduces symptoms of sleeplessness. Chronic use can lead to fatigue, restlessness, hearing and sight hallucinations and psychotic personality changes.
• Benzodiazepines and other central nervous system depressants are sedatives and impair reaction time, reflexes and coordination skills.
• Cannabis impairs reaction time, reasoning and overall brain function. Its effects can last several hours and appear to vary according to quantity, quality and content.
• Opiates sedate the user and result in sleepiness, slow reflexes and changeable moods. Regular use can also result in psychological problems and withdrawal symptoms include irritability, physical discomfort and a very unstable personality.

• impaired reaction times
• fatigue, and
• impaired perception loss of attention.

To clarify the impact of drugs on driving effectively, the following research by Drummer looked at the influence of a variety of drugs on driver culpability. Use of all of the drugs identified shows an increase in relative risk except for cannabis, which shows a slight decrease. It is also of note that relative risk is nine times greater when alcohol and drugs are used together than when drug free. According to Drummer, the combination of alcohol and cannabis does not increase the relative risk any more than does alcohol alone.

TABLE 6: RELATIVE RISK BY SPECIFIC DRUG GROUPS