In South Australia, illicit drugs surpassed alcohol in crash-involved drivers and riders, with drug-positive rates rising from 10.5% to 15.2% while illegal alcohol rates fell from 20.2% to 9.3% over roughly a decade.
Road safety policymakers, law enforcement, and public health officials.
Drug-positive crash rate: 15.2%, up from 10.5%
What the researchers found
Over 15% of crash-involved drivers and motorcyclists tested positive for proscribed drugs (THC, methamphetamine, or MDMA), compared to about 11% of drivers and 5% of motorcyclists with illegal blood alcohol. THC was found in 6.3% of drivers and 9.4% of motorcyclists. Drug rates increased from 10.5% (2008-2010) to 15.2% (2014-2017) while illegal alcohol rates declined from 20.2% to 9.3%.
Why it matters
The shift from alcohol to drug impairment in crashes represents a changing landscape that requires updated enforcement strategies and public messaging.
The numbers in context
Drivers: methamphetamine 9.7%, THC 6.3%. Motorcyclists: THC 9.4%, methamphetamine 6.2%. Drug-positive rate: 10.5% (2008-2010) to 15.2% (2014-2017). Illegal BAC: 20.2% to 9.3%.
How the study worked
Analysis of mandatory blood test results from crash-involved road users over age 16 at the major trauma hospital in Adelaide, South Australia (2014-2017), compared to earlier data (2008-2010).
What this study cannot tell us
Single trauma hospital. Only three drugs tested. Positive test does not confirm impairment at time of crash. Comparison to earlier data involves different methodology nuances.
How to read the evidence
Mandatory testing data from a major trauma hospital provides reliable detection, though limited to one hospital and three drugs.
When this study was published
2020 study using 2014-2017 data.
The bigger picture
As alcohol countermeasures succeed in reducing drunk driving, drug-impaired driving is filling the gap, potentially undermining overall road safety gains.
Questions still open
- Are current roadside drug testing programs effective at deterring drug-impaired driving? Is the rise in drug-positive crashes offsetting the decline in alcohol-related crashes?
Common questions
Are drugs or alcohol more common in car crashes?
How common is cannabis in crash victims?
Read the original research
Illicit drugs are now more common than alcohol among South Australian crash-involved drivers and riders.
Traffic injury prevention, 21(1), 1-6
Citation
Baldock, Matthew; Lindsay, Tori. (2020). Illicit drugs are now more common than alcohol among South Australian crash-involved drivers and riders.. Traffic injury prevention, 21(1), 1-6. https://doi.org/10.1080/15389588.2020.1712715