Nearly three years after California voters approved a cannabis legalization bill that promised, among other things, to clarify the issue of driving while high, researchers and law enforcement have few concrete answers about a potentially deadly problem.
Its unclear, for example, if marijuana-related arrests or car crashes have increased statewide. Its up to each county to track that data, and many still dont distinguish between cannabis and other drugs in their arrest and accident reports.
There also arent yet any reliable methods for testing whether drivers were actually impaired by marijuana when theyre behind the wheel. Research in this area is hampered by federal law and left scrambling to catch up with the wave of marijuana legalization that continues to sweep the country.
These are some of the challenges police officers, attorneys, politicians and leading cannabis researchers discussed Friday during a day-long forum on marijuana and driving at UC Irvines Center for the Study of Cannabis.
“We need more data to understand what is happening, what isnt happening, and to even begin to measure the effects,” said Rep. Katie Porter, D-Irvine, who spoke during the forum.
There are signs that some clarity could be coming soon.
The Center for Medical Cannabis Research at UC San Diego is “weeks” away from releasing findings of a three-year, state-funded study into effective roadside tests for marijuana impairment, according to Dr. Robert Fitzgerald, a clinical pathologist involved in the project.
Also, some law enforcement agencies are starting to track data on cannabis and driving. And legislation is pending from State Sen. Pat Bates, R-Laguna Niguel, that would require testing for cannabis in all fatal crashes.
“We have a lot of work to do,” said Bob Solomon, a UCI law professor who serves as co-chair of the schools cannabis research center. “But we will get there.”
Trouble with testing[hhmc]
The rules with cannabis and driving are pretty much the same as with alcohol. Adults cant consume marijuana while driving. They cant have an open container thats accessible. And they cant be under the influence of marijuana while behind the wheel, since its been shown to cause increased weaving and other problems — particularly if combined with alcohol.
The problem is how to measure marijuana impairment.
While alcohol and harder drugs like methamphetamine are generally filtered out of the system in less than a day, signs of cannabis use can turn up in blood and urine tests long after the drugs mind-altering affects have worn off. And since marijuana is stored in fat cells, many factors affect how quickly the body metabolizes the drug, including the persons tolerance, how they ingested it, the pots potency and even their gender.
Research shows it generally takes women longer than men to filter marijuana out of the system, according to Dr. Marilyn Huestis, a toxicologist and world-renowned expert on drug testing who spoke during Fridays UCI forum. Huestis also said shes seen blood levels of THC (the main compound in cannabis that makes people high) actually go up over time if people were physically active, releasing chemicals stored in their fat cells.
All of that makes it tough to tell with traditional drug tests whether a driver was impaired while behind the wheel or simply used cannabis hours, days or even weeks before. Thats particularly true when it comes to medical marijuana patients, who may use small amounts of cannabis daily, and frequent recreational consumers, who may show high levels of THC even when theyre not impaired.
Thats why, unlike with the established legal threshold of 0.08 percent blood alcohol content, theres no clear scientific standard in California to determine when a driver is illegally impaired by marijuana.
Six states have adopted “per se” limits on the amount of active THC allowed in the blood before drivers can be considered impaired. The amounts range from 0.5 nanograms per milliliter in Pennsylvania to 5 nanograms in Washington. But studies by the AAA Foundation and others have found no scientific basis for such numbers. Huestis agreed, saying theres not a good scientific case right now for per se limits.
UC San Diego hopes to have recommended solutions soon. Researchers are having 180 volunteers smoke marijuana and then participate in driving simulations. Those volunteers also are asked to complete tasks on an iPad, which could become a cannabis field sobriety tool. In addition, they undergo blood, breath and saliva tests at regular intervals.
In the meantime, if an officer sees signs of impaired driving, and a blood test shows that person has any amount of cannabis in their system, they can be charged with driving under the influence.
Lack of data confuses issue[hhmc]
Drug-related DUI cases nearly quadrRead More – Source
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