A new survey of Massachusetts residents found more than a fifth of adults said they'd used marijuana in the past 30 days. The study was commissioned by the Massachusetts legislature, to help gauge the eventual impact of marijuana legalization in the state.
New England Pulic Radio's Adam Frenier spoke with Jennifer Whitehill, a UMass Amherst professor who helped author the study, and asked about public perception of the drug.
Whitehill: Around 50 percent of adults really see little or no risk with marijuana. And that's not only the users who responded, but was reflective of the whole population.
Frenier: And in the study there were a number of young people that were asked about this. What can you tell us about that 18-to-25-year-old range?
A big takeaway from this is that it is younger age ranges who tended to have a higher prevalence rate of using marijuana, compared to older age groups.
And how are they using it? How are they ingesting it?
What I guess at this point would be considered old-fashioned smoking remains the most common way to use marijuana. But sizable proportion of the users in this study -- I think it was a little over 40 percent -- they also used it in other ways, which included things like edible products and vaporizing.
The study also showed that people who use marijuana and then shortly thereafter drive a vehicle. What can you tell us about that?
Because the survey was weighted for the population, we can talk about estimates for two different groups. We can talk about the general population of Massachusetts and we can also talk about marijuana users.
And so, we found that about 7 percent of all adults in Massachusetts reported driving under the influence of marijuana in the past 30 days. When we limit that and look only at the marijuana users, those numbers ranged as high as about 35 percent.
Is there any correlation between marijuana use and car accidents?
That's a great question. In the public health field and the epidemiology to date, there are a lot of challenges trying to pin a specific number down for the risk of a car crash due to marijuana. And numbers that you hear -- when I talk about this, I say something in between probably a 20 percent increase in risk and maybe a doubling of risk, we also hear that. That is work that is existing epidemiological research that did not come from this baseline study.
That said, in this study, they did want us to look at how you might be able to detect marijuana in drivers. And we looked into what the literature says about available devices for testing for this. We really find that although there are ways to measure marijuana use in blood or in the oral fluid [saliva] of drivers, that is not correlated with impairment. And that's a really critical thing to be able to say someone used, but what was the time window for that use? We can't say that only from a level the way we can with alcohol. And we also can't know whether a level that you might measure in someone's oral fluid, for example, was correlated with impairment at the time of driving.