DRUG-DRIVING SALIVA TESTS MAY NOT BE ACCURATE

Scientists are testing the accuracy of saliva tests in detecting
drugged drivers, following research showing that the problem is more
widespread than drink driving.

Research from Otago University's long-running Christchurch Health and
Development study released yesterday showed 25-year-olds more commonly
drove while under the influence of cannabis than alcohol.

The Otago University figures supported Environmental Science and
Research (ESR) data published by The Press this week which gave the
first glimpse of the huge problem of drugged drivers on New Zealand
roads.

The results of the Otago study also came as Parliament considered
legislation to give police greater powers to test and arrest drugged
drivers.

In response to the new figures on the scope of drug driving, ESR
scientists have launched a study into how effective a saliva cannabis
test is in detecting recently consumed drugs.

It is hoped police will in future be able to use the saliva tests to
accurately detect whether someone is still under the influence of
cannabis while behind the wheel.

Almost 1000 25-year-olds took part in the Otago University research
and were asked how many times in the last four years had they driven
either dangerously drunk or soon after smoking marijuana.

Participants said they had driven while under the influence of
cannabis an average of nine times in four years, compared to about
three times while drunk.

The lead researcher for the Otago University study, Professor David
Fergusson, said he was very surprised by the research results. "We
never expected to see that cannabis was going to be a bigger problem
than drink-driving but that's what we found."

Fergusson said drink-driving had decreased while cannabis use had
increased "dramatically" over the decade or so.

More than 80 per cent of 25-year-olds in the study said they had
smoked cannabis, Fergusson said.

Under legislation currently being considered by Parliament, police
will put suspected drugged drivers through a roadside test of balance,
co-ordination and eye-pupil response tests. If they appear to be
affected, they will be ordered to have a blood test.

Critics of the legislation argue blood tests detect cannabis in a
person's system long after they have smoked it. The scientist in
charge of an ESR and police project to measure the numbers of dead
drivers who had taken drugs disputed the claim.

ESR forensic toxicologist Helen Poulsen said blood tests picked up the
presence of cannabis in a person's system from between four hours and
24 hours after they had smoked it.

There were currently some issues with the accuracy of saliva tests,
Poulsen said.