Road side testing of cannabis
"The level of impairment might not be as severe as alcohol intoxication, but it's there and it does require a public health response," said Professor Wayne Hall, from the University of Queensland Centre for Clinical Research.
In Australia, roadside drug testing was first introduced in Victoria in 2004, and has since been adopted by most other states and territories.
But it is unclear whether this strategy is effective, Professor Hall wrote in a separate commentary in the BMJ.
"We've implemented this policy in most states and territories and there just doesn't seem to be the commitment to finding out whether this has been effective or not," he said.
The problem, he argues, is that roadside drug testing has been modelled on the success of random breath testing, but hasn't been evaluated or implemented with the same rigour.
"We don't really know if that's worked and there are very important differences in which roadside drug testing has been done compared with random breath testing," Professor Hall said.
He says while it is relatively easy to measure blood alcohol levels using a breath test, it is much harder to gauge impairment from concentrations of THC in the saliva, so governments use 'zero tolerance' to define impairment.
"[Governments have] simplified it in a sense and avoided the issue of what the level [where driving is impaired] might be," he said.
He says the other issue is that roadside testing has not been as widely implemented or as well publicised as random breath testing.
"I think we need to look at the extent to which people who use cannabis are deterred from driving when they use cannabis. Are they fearful of being detected? Is this a realistic deterrent?" he said.
"We need to do similar things with cannabis [that we did with random breath testing], and probably focus more on younger drivers because that's where use is likely to be highest."
http://www.abc.net.au/news/2012-02-10/smoking-dope-doubles-risk-of-car-crashes/3822668
