Marijuana public health effects aired at UMass symposium

  • Panelists speak Monday, April 2, 2018, at a University of Massachusetts Amherst symposium on legalized marijuana and its public health research and policy implications. —DUSTY CHRISTENSEN

Published: 4/2/2018 8:51:05 PM

AMHERST — As recreational marijuana legalization rolls out across the state, University of Massachusetts researchers are digging into the potential public health effects of that reality.

At a symposium Monday at UMass, David Buchanan, chairman of the department of health promotion and policy, laid out what he said are the three biggest issues currently on the minds of public health experts: youth drug use, the increased development of addictive patterns of drug use among predisposed people and “drugged-driving impairment.”

The event came on the same day the state’s Cannabis Control Commission began accepting applications for recreational retail locations, which are set to open on July 1.

In addition to UMass researchers, the university invited Darrin Grondel, the director of Washington state’s Traffic Safety Commission, to speak on his state’s experience.

“Ultimately, this stuff impairs and it could hurt people,” Grondel said.

Grondel cited a national survey that shows that while drunken driving has become socially unacceptable, there is “almost a public indifference to drugged driving.”

“How do we help change that message and start to address it?” he asked.

Grondel also mentioned a voluntary and anonymous roadside survey that his state conducted with the National Highway Traffic Safety Administration, which seems to show that more drivers were found to be THC-positive one year after retail cannabis sales began than immediately before. THC — tetrahydrocannabinol — is the principal psychoactive chemical compound in cannabis.

Roadside research

Washington provides an interesting example for Massachusetts, given that retail cannabis sales began there in 2014. Washington, however, has vastly different laws when it comes to determining whether a driver is impaired on marijuana or other drugs.

In Washington, a law was passed that allows for a “per se” OUI threshold of five nanograms of THC per milliliter of blood drawn. In other words, anyone over that limit is presumed impaired. That limit, however, is not based on any scientific conclusion, and Grondel said it does little to actually measure impairment. Perhaps for that reason, Massachusetts has no such threshold yet.

Quantitatively measuring marijuana impairment is notoriously difficult for many reasons, said Jennifer Whitehill, an assistant professor at UMass.

Some of those reasons include the challenges of collecting blood for a sample and the large variability of THC levels among individuals based on factors like metabolism, differing impairment effects, which product was consumed, and the user’s frequency of use.

Whitehill said that an oral-fluid THC test is in the final stages of approval for federal workplace drug testing, and that in other countries such measurements are used in roadside sobriety tests. However, she said, results can differ if a driver has consumed edible marijuana instead of smoking it.

With biological tests not yet sufficient for measuring impairment, law enforcement has to rely on other observations that are restricted by state law.

The Massachusetts Supreme Judicial Court in September ruled that an officer cannot use the results of a field sobriety test when giving testimony on whether a driver was intoxicated on marijuana. The officer can, however, provide testimony on observed physical characteristics, like whether the driver has bloodshot eyes or impeded coordination.

Given that context, Whitehill said, survey data are very important in determining what driver behavior actually looks like on a larger scale. She mentioned surveys of adult marijuana users in Colorado and Washington showing high levels of reported driving after consumption, and said survey data also show that more teens in Massachusetts are driving after consuming marijuana than are driving after drinking alcohol.

“It probably has to do with the safety perceptions,” she said.

One of the biggest issues facing public health researchers is a dearth of data actually available on marijuana, speakers noted at Monday’s symposium. A big reason for that is the fact that the federal government still classifies cannabis as a Schedule 1 drug, defined as “drugs with no currently accepted medical use and a high potential for abuse.”

For that reason, little research exists on matters like drugged driving, and what does exist is based on marijuana with levels of THC that fall far short of the potency of marijuana currently on the market.

Future indicators

Researchers here in Massachusetts do plan to tackle the task of gathering the data needed to begin answering many questions, however.

UMass Amherst and UMass Donahue Institute researchers, together with the state Department of Public Health, recently finished the first draft of a one-year baseline study of pre-legalization marijuana use rates, as well as potential impacts like impaired driving and emergency room visits.

Whitehill was one of the UMass researchers who worked on that study, as was UMass professor Elizabeth Evans.

Although Whitehill couldn’t disclose detailed results from the baseline study, she did speak to some findings that could influence the kind of research the state decides to do going forward.

One thing Whitehill noted is that when looking at fatal motor vehicle crashes, more attention needs to be placed on testing for marijuana or other drugs so as to understand the impact they might be having on drivers.

“What we see is that about 75 percent of deceased drivers are actually tested, but almost no surviving drivers are being tested,” she told the audience. “Right off the bat, that’s a really important area for moving forward.”

Other areas for potential future research, she said, include improved quantitative impairment measurements for marijuana, studies of nonfatal crashes, and roadside studies like the one conducted in Washington.

Other presenters on Monday included Evans, who discussed gender differences with regard to cannabis use disorders, and Cheryl Sbarra, a staff attorney with the Massachusetts Association of Health Boards, who discussed what municipalities can do to regulate marijuana at the local level.

Among those in attendance Monday were local police, Amherst health officials, representatives from the local marijuana industry, academics and two members of the state’s Cannabis Control Commission.

“I can’t overstate how important it is that there is a dialogue,” Britte McBride, a commission member, told the Gazette after the event. “The commission is invested in making sure we do this well and do this right.”

Dusty Christensen can be reached at

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