Research: Drugs & Driving

Drugs & Driving, Prevention Research Quarterly, DrugInfo Clearing House Australian Drug Foundation

Professor Con Stough and Rebecca King, Drugs and Driving Research Unit, Brain Sciences Institute, Swinburne University, Melbourne, Victoria

Detection of impaired driving

Although education is an important contributor to the reduction in the number of drivers consuming drugs, for some individuals there also needs to be a perception that there are valid methods of detecting drug-drivers by police. Without the risk of being identified, fined or prosecuted, education is not sufficient to deter some individuals from consuming drugs and then driving.

Victorian sobriety testing

Currently the Victorian police use the Standard Impairment Assessment (SIA) to identify the presence of impairment in drivers believed to be under the
influence of drugs other than alcohol. If a police officer observes a serious driving impairment they can require the driver to undertake the SIA. The SIA is a structured and systematic assessment that is carried out by trained police officers.

The assessment consists of four components:

• Interview and observation (a standardised series of questions that examine the circumstances that led to the detainment of the suspect, as well as recent history of illness, injury, medical treatment and drug use);
• Physical impairment test;
• Information review process; and
• Opinion on the presence of impairment.

The physical impairment test consists of the horizontal gaze nystagmus, the walk and turn test, and the one leg stand test.
These tests allow impairment to be identified at a level that is equivalent to the impairment at a BAC of 0.05 per cent or above. When impairment is identified by the officer, a blood or urine sample is taken to confirm the decision. During the first 12 months of the drug detection program in Victoria, police identified a total of 227 individuals suspected of driving while impaired by a drug.
Of these 227 suspects, 181 were charged with offences. Convictions were obtained in 27 cases with 133 remaining in the court system; thus far no cases have been dismissed.

The results suggest that the Victorian SIA procedure is effective in identifying and removing drug-impaired drivers from the road.

Cannabis

…In line with these findings, a study funded by the National Drug Law Enforcement Research Fund (NDLERF) at the Drugs and Driving Research Unit
(DDRU) at Swinburne University in Melbourne found that the consumption of low-dose and highdose cannabis was associated with an increase in vehicle lane-weaving (straddling solid and barrier lines).

Cannabis impairment is most prominent in the first 2 hours after smoking; however, driving performance has been shown to be compromised up to 5 hours after cannabis consumption. Drivers can be impaired first by cannabis intoxication, and later in the residual phase due to fatigue and inattention.
Despite common stereotypes regarding the low risk of having an accident under the influence of cannabis, there is no doubt that cannabis poses a significant crash risk for drivers.

MDMA

An ecstasy (MDMA) pill takes effect after 30–45 minutes, starting with little rushes of exhilaration, and with intoxication lasting up to 5 hours. Along with the positive feelings for which the drug is taken, users may experience disorientation, dry mouth, blurred vision and involuntary muscular activity.

Current problems, issues and suggestions for the future

Although saliva testing for drugs has been successful in detecting drug-affected drivers, there is still only a limited number of drugs tested and at levels for some drugs that may only measure recent use. We know that many drugs, even at low levels or many hours after use, can still impair driving.

Developing a wider battery of drugs tested may deter many drivers from driving. Of course not all drugs impair driving and the detection of low concentrations of certain drugs may merely be detecting those drugs and not driving impairment. This problem may be solved by the development of computerised roadside assessments for cognitive and motor functioning. This may be particularly important in detecting drivers who are showing fatigue (who have not consumed drugs) and drivers who are rebounding from previous drug taking, such as the case of amphetamine users (i.e. who have no levels of amphetamines in their
system but who show great impairment in driving).

Drugs & Driving, Prevention Research Quarterly, DrugInfo Clearing House Australian Drug Foundation

Professor Con Stough and Rebecca King, Drugs and Driving Research Unit, Brain Sciences Institute, Swinburne University, Melbourne, Victoria