Three years into legal marijuana and California still doesn’t have a reliable test for driving while high

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.

It’s unclear, for example, if marijuana-related arrests or car crashes have increased statewide. It’s up to each county to track that data, and many still don’t distinguish between cannabis and other drugs in their arrest and accident reports.

There also aren’t yet any reliable methods for testing whether drivers were actually impaired by marijuana when they’re 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 Irvine’s Center for the Study of Cannabis.

“We need more data to understand what is happening, what isn’t 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 school’s cannabis research center. “But we will get there.”

Trouble with testing

The rules with cannabis and driving are pretty much the same as with alcohol. Adults can’t consume marijuana while driving. They can’t have an open container that’s accessible. And they can’t be under the influence of marijuana while behind the wheel, since it’s 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 drug’s 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 person’s tolerance, how they ingested it, the pot’s 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 Friday’s UCI forum. Huestis also said she’s 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. That’s 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 they’re not impaired.

That’s why, unlike with the established legal threshold of 0.08 percent blood alcohol content, there’s 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 there’s 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

Drug-related DUI cases nearly quadrupled in Los Angeles County over the past two years, according to Ricardo Santiago, spokesman for the district attorney’s office. The LA County office reviewed 375 cases in 2017 and 1,469 cases in 2018, which is the year shops could begin legally selling recreational marijuana.

But those figures include all drug impairment cases, without distinguishing between cannabis and illegal narcotics. That’s also how Riverside County District Attorney’s Office tracks impaired driving cases.

The Orange County Crime Laboratory is one of just a few in the state that for years has tested all fatally-injured drivers for a range of drugs, including cannabis, according to the lab’s assistant director Jennifer Harmon.

In 2016, 5 percent of drivers who died in crashes had only marijuana in their systems. In 2018, that number rose to 11 percent.

There were similar increases in that same time frame of drivers in fatal crashes with alcohol and other drugs in their systems.

It’s expected that more people would be using marijuana now that it’s legal. So until those tests can more effectively measure impairment vs. past cannabis use, it’s tough to draw conclusions about how legalization is impacting the safety of California’s roads.

There’s also no centralized collection point in California that aggregates driving under the influence violations by drug type, according to Fran Clader, spokeswoman for the California Highway Patrol.

The CHP — which is supposed to get $3 million from cannabis tax revenue each year through summer 2023 to develop better testing protocols — has preliminary data for crashes in 2018 and this year so far where officers suspected cannabis was involved. But Clader said that data isn’t yet verified by toxicology samples, which can take months. And the figures don’t distinguish between crashes where the driver only consumed cannabis vs. cases where drivers had other substances in their systems.

The agency is working on new methods to track and separate that data, Clader said.

Rep. Porter pushed for a sense of urgency.

“We don’t want to be complacent,” she said, only to learn accidents and deaths could have been prevented.

Source: mercurynews
Three years into legal marijuana and California still doesn’t have a reliable test for driving while high