Citation

Ogden EJD, Morris C, Frederiksen T, Stough C, King RR, Donald J. Proc. Australas. Road Safety Res. Policing Educ. Conf. 2011; 15.

Copyright

(Copyright © 2011, copyright holder varies, Publisher Monash University)

DOI

unavailable

PMID

unavailable

Abstract

Drivers taken to hospital in Victoria after a collision must provide blood for analysis for the proscribed drugs (cannabis, MDMA, methamphetamine). A longitudinal study is examining a range of other substances including benzodiazepines, opiates, and other psychotropic medication and matching toxicology results to police collision reports. Each driver is assigned a degree of responsibility according to the method of Robertson. If a substance causes impairment, then drivers in whom the substance is found are likely to be “responsible” for the collision than those who are drug or alcohol free. 1802 samples have been analysed to date. Of the alcohol-positive drivers, 96 per cent were responsible for their collision. This paper focuses on the benzodiazepine tranquilisers. Benzodiazepines were detected in 10.2 per cent of samples (n=184). Preliminary evidence suggests there is a dose relationship with small increase in collision risk at therapeutic levels and high risk at toxic levels. Abuse of prescription drugs is a road safety issue worthy of specific study and targeted interventions. The combination of benzodiazepines and alcohol was associated with increased responsibility for collision even when the prescribed drugs were present at therapeutic levels. Combining drugs increased the likelihood of responsibility for collision: drug-free drivers – 45 per cent were responsible; with 1-2 drugs – 80 per cent were responsible; with 3 drugs – 94 per cent were responsible; and with 4+ drugs – 96 per cent were responsible. It is now possible to test for benzodiazepines at the roadside. An enforcement measure that may improve road safety would be to adopt zero tolerance for alcohol when benzodiazepines are prescribed. The ongoing study will continue to examine dose relationships and specific drug interactions, which will inform development of targeted counter-measures.