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Drugs and Driving What the research tells us.
Robyn Robertson, M.C.A President and CEO Traffic
Injury Research Foundation Countermeasures
XVII Toronto, ON, November 3, 2008
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Drugs and driving

• Drugged driving is an emerging traffic safety
  issue.
• Highly controversial and often confusing.
• Many claims fewer solid facts.
• Near hysteria can surround the issue societal
  ambivalence alcohol (OK) drugs (not OK).
• Moral overtones illegal (bad) versus legal
  (good) drugs.

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Complex issue

• Drugs and driving is a much more complex issue
  than drinking and driving.
• We know and understand much more about alcohol
  its properties are consistent.
• Complexities of drugs account for shortcomings in
  knowledge and different interpretations of
  evidence.

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Research challenges

• Large sample sizes.
• More intrusive tests.
• Refusal rates are high.
• Collection, storage, analysis issues.
• Correlation between drug level in blood and
  impairment is low or unreliable for many drugs.
• Elimination rates timing of testing.
• Wide range of analyses are expensive.

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Why it is so complicated?

• Many different drugs highly complex chemicals.
• Different populations of users some are
  difficult to identify.
• Different usage patterns according to
  prescription in combination.
• Effects (pharmacodynamics) differ by drug and
  user (tolerance over time).
• Testing for presence vastly more complex than
  testing for alcohol.

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Key questions

• Do drugs impair skills/abilities needed for safe
  driving?
• Do people actually use these drugs while they are
  driving?
• Are drivers who use them involved in collisions?
• Is there evidence that the presence of the drug
  caused the crash?
• How have jurisdictions responded to the issue?

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Do drugs impair driving skills

• Yes. Experimental studies show a wide range of
  drugs impair critical skills and abilities (e.g.,
  response times, concentration).
• Some have a potent impact particularly those
  with a sedative/hypnotic effect. Some have a
  moderate effect (cannabis) some are less likely
  to cause impairment (stimulants).

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Do drugs impair driving skills

• Experimental studies have a number of
  limitations.
• They take place in a controlled environment.
• Measures of performance, not judgment.
• Only low doses of drugs are tested for ethical
  reasons.
• Impact on real-world experience not known.

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Do drugs impair driving skills

• Epidemiological (real world) studies are weak and
  vague.
• Two types (case control and crash
  responsibility/culpability analysis), both of
  which have weaknesses.
• The evidence that marijuana is related to crash
  risk is mixed. Some studies report that the crash
  risk is actually lower than the average driver,
  others report crash risk is 1.5-2.5 times
  greater one study said 6.4.
• Studies of benzos show the crash risk is 1.6-5
  times greater.

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Do people use them and drive?

• Yes, but... Data on frequency and quantity of
  drug use in the driving population are sketchy.
• Best estimate is that about 10 of drivers are
  using impairing drugs.
• Marijuana is the most commonly reported/detected
  and most common among young males.

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Do people use them and drive?

• TIRF public opinion poll revealed 15 of driving
  population had taken prescription or over the
  counter medication within two hours of driving.
• Marijuana use increased from 1.2 to 2.4 in
  past few years. (An estimated 500,000 people).

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Do people use them and drive?

• NHTSA 2007 roadside survey tested for drugs.
• Victoria, Australia used random saliva testing
  and found 1 in 100 drivers were positive for
  alcohol 1 in 50 drivers were positive for drugs.
• Officers on west coast in North America report a
  sharp increase in drugged impaired driving.

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Do people use them and drive?

• No profile of a drugged driver.
• Marijuana is the most commonly reported/detected
  and most common among young males.
• Some suggest that young people are substituting
  drugs for alcohol.
• Prescription medications much more common among
  older populations.
• Women tend to be over-prescribed by doctors.

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Are drugged drivers involved in crashes?

• Yes. Overall incidence of drug detections among
  drivers killed or injured in road crashes is in
  the 14-17 range.
• Most commonly detected substance is cannabis
  (about 10-11 of cases) next are benzodiazepines
  (class of drugs with hypnotic, anticonvulsant,
  and properties) found in about 5-9 of cases.

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How many crashes are caused by drug impairment?

• Unknown, because the evidence of the contribution
  of drugs to crashes is inconsistent and
  inconclusive.
• Testing of fatally injured drivers is low.
• Drugs frequently detected in blood in combination
  with alcohol (up to 75).
• Challenge to distinguish between the effects of
  the drugs and the characteristics of the users
  (e.g., risk taking among some users reduced
  skills in general among elderly).

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Responses to drugged driving?

• Per se (zero tolerance) and impairment-based
  laws
• Impairment Austria, Denmark, Netherlands,
  Norway, Portugal, Ireland, UK.
• Per se France, Switzerland, Sweden
• Both Belgium, Germany, Spain Finland.
• Random testing Belgium, Denmark, Germany,
  Spain, Italy, Portugal, Finland, Norway.
• Suspicion France, Ireland, Austria,
  Netherlands, Sweden, UK.

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Responses to drugged driving?

• Per se (zero tolerance) and impairment-based
  laws.
• Effectiveness of laws is unknown.
• Some police, courts have no protocols in place
  to handle cases.
• No research to guide policies.
• Few cases go to court always take alcohol over
  drug case.
• Focus on drugged driving or drug users?

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Challenges in Canada?

• Training for Crown and judiciary.
• DRE process needs to be upheld in Court.
• DRE evidence is open to challenge not yet
  accepted by the Courts.
• Officers cannot interpret DRE evidence in Court
  need for expert.

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Challenges in Canada?

• Lab processing time and resources.
• More evidence for Crowns to lead.
• Length of trials.
• Not a lot of case law to rely upon.

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Summary

• Many drugs impair skills and abilities deemed
  important for the safe operation of a vehicle.
• Many of these drugs are used by people when they
  drive.
• Many of these drugs are found in drivers involved
  in collisions.
• The risks (contributory effects) are not well
  established.
• On balance the evidence shows that the problem is
  by no means trivial even though still not well
  understood.

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Staying informed

• www.tirf.ca