Illicit drugs are now more common than alcohol among South Australian crash-involved drivers and riders.

For a jurisdiction to apply appropriate countermeasures for impaired driving, it is necessary to track drug and alcohol involvement in road crashes. In South Australia, it is mandated that all injured road users aged over 10 who attend a hospital for treatment must have a blood sample taken, which is tested for alcohol and drugs. The drug testing covers the three drugs included in South Australia's roadside drug testing program: delta-9-tetrahydrocannabinol (THC or cannabis), methamphetamine ('ice') and 3,4-methylenedioxymethamphetamine (MDMA or 'ecstasy'). The present study involved analysis of the results of drug tests from 2014 to 2017 for road users over the age of 16 at the major trauma hospital in Adelaide, the capital city of South Australia. Comparisons were made to the results of blood tests from an earlier study using data from 2008 to 2010. It was found in the most recent dataset that just over 11 per cent of drivers and just under 5 per cent of motorcyclists had a blood alcohol concentration (BAC) above the legal limit of 0.05 g/100 ml. In regard to the three proscribed drugs, the rates for both drivers and motorcyclists were over 15 per cent. Among drivers, methamphetamine was most common (9.7%), followed by THC (6.3%). Among motorcyclists, THC was most common (9.4%), followed by methamphetamine (6.2%). Inspection of data from 2008 to 2010 reveals that rates of having an illegal BAC when involved in a crash have declined over the past decade (from 20.2% down to 9.3%), while rates of drug use among crash involved drivers and riders have increased (from 10.5% to 15.2%). Although the apparent decline in alcohol involvement in road crashes in recent years in South Australia is to be welcomed, the increasing proportion of road crashes involving drug impaired drivers, particularly those affected by methamphetamine, is cause for concern. A National Drug Driving Working Group has been set up by Austroads to examine improvements in drug driving enforcement practices. The recommendations arising from their work need to be considered for implementation to prevent rising drug driving crashes from replacing the reduction in road crashes attributable to drink driving.