Cannabis saliva testing - will it surge NSW road deaths?

Drug Free Australia

The NSW Government-proposed 50ng/ml cannabis in saliva threshold bears no relationship to cannabis driver impairment, where 1ng/ml constantly correlates with fatality-causing impairment.

Drug Free Australia has informed the NSW Government that its announced 50ng/ml threshold for cannabis in roadside saliva testing is culpably ignorant of an extensive science demonstrating that even 1ng/ml in saliva correlates with cannabis driver impairment.  The NSW Government plans to allow drivers under the 50ng threshold to receive warnings if they have a medical cannabis prescription.

Cannabis impairs driving for 5-7 hours for those using vaporised cannabis and some hours longer if taken orally.  Yet meticulously recorded scientific studies of THC levels in blood and saliva comprehensively show that 80-90% of THC is quickly eliminated within the first 1-2 hours despite driving impairment lasting at least 3 hours longer because the highly fat-soluble THC is quickly absorbed by the brain, the body’s largest fat-rich organ (60% fat) - which also happens to be the seat of impairment. 

Despite driving impairment lasting hours longer, a meticulous 2019 study found only 5 of 17 subjects - after inhaling 25mg of THC - had levels exceeding 50ng/ml at the 60 minute mark, and only one at the 2 hour mark.  59% had THC levels of 1-2ng/ml after 4 hours, despite impairment lasting at least another hour.  This demonstrates that any fluid testing for THC, whether blood or saliva, is incapable of determining driver impairment.  Below-threshold THC readings most certainly DO NOT indicate low impairment.  Another study, most notably, of 62.5 mg and 125 mg of THC taken orally in capsule form found NO THC in the saliva. Thus THC, once in the blood, does not migrate into saliva.  So a driver can be severely impaired by a high dose of capsule THC while measuring zero in saliva testing.  This study suggested 9-10 hours before driving. 

Drug Free Australia has previously shown NSW politicians that Colorado’s introduction of shopfront medical cannabis in 2009 saw a 54% increase in cannabis monthly use by 2019, while cannabis driver fatalities as a percentage of all road fatalities skyrocketed 230% above 2009 fatalities, with similar effect seen in Washington.

We must do everything to avoid escalating road deaths.  The Premier is being asked to meet with Drug Free Australia which has a deep international bench of experts in testing/medicine/pharmacology to present the science.  It has also urged the Premier to release the science behind their 50ng threshold for public scrutiny.  For the actual studies cited here and their data, see attached Backgrounder.

Gary Christian
PRESIDENT
Drug Free Australia
0422 163 141 (available from 8 am)