ON THE GRASS? STAY OFF THE ROAD

Marijuana smokers tend to drive more slowly but that does not make them any
safer.

They have trouble staying in their lanes and making quick decisions when
something unusual happens, research shows.

Swinburne University researchers have been testing the effects of marijuana
and alchohol on driving.

They have found that regular pot smokers are better drivers than occasional
users while under the influence of the drug.

Katherine Papafotiou, of the university's drugs and driving unit, said 80
regular and non-regular marijuana smokers had volunteered for the trial,
which was continuing.

Over six sessions they smoked marijuana, drank alcohol, and then jumped
behind the wheel of a driving simulator.

"With marijuana alone, we found significant impairment in the individual
maintaining specified positions within designated traffic lanes... there
was a lot of weaving over barrier lines and solid lines," Dr Papafotiou said.

"Non-regular users were more impaired... and the level of THC (the active
ingredient in marijuana) was higher in regular users."

Occasional smokers also recorded many collisions and had slower reaction
times, which could be detrimental in emergency situations.

The conclusion - that regular users might be slightly more tolerant to
marijuana's driver-impairing effects - is just one problem in developing an
accurate roadside saliva test for all drug classes.

Dr Papafotiou said an accurate roadside test was at least three years away.