a gray market is just a black market with lobbyists

Many of us who have long advocated for the legalization of marijuana decided at some point to embrace the medical marijuana movement as a wedge issue to advance the greater cause of full legalization. Some perhaps more consciously than others. Personally, I was sold on legalization long before anyone convinced me of any medical benefit to cannabis, so I cannot really say that the medical argument ever moved me. But I will admit to having happily deployed the image of federal agents handcuffing the terminally ill to their beds during raids as a rhetorical tool for people on the fence.

I think that the time has come to acknowledge that embracing medical pot was a strategic mistake for those of us who really want much, much more than that.

Here in Washington, we will be voting on I-502 this fall, which would legalize marijuana for personal use by persons over 21 years of age, and create a state regime for its regulation and taxation. Part of the proposal deals with impaired driving, and sets the blood level of delta-9 THC for pro se DUI at 5.0 ng/ml. Anyone with half an ounce of common sense (or perhaps an eighth of uncommon sense) can see that setting some objective limit for impairment is absolutely necessary, both for public safety reasons and for the political necessity of selling this thing to the general public.

Enter the medical marijuana establishment in Washington, who have argued that this limit will result in patients getting hit with DUI charges because they are chronically above the legal limit. Which leaves us in an interesting position: one of the largest and most vocal groups opposing the present attempt to reform marijuana laws in this state is the group that has previously and successfully reformed marijuana laws in this state.

The problem is, the science doesn't support their assertions at all. In fact, if you read through Dominic Holden's recap of the science cited by the medical MJ activists themselves, you'll see that it actually takes a hell of a lot of pot to achieve the legal threshold in the bloodstream beyond the first hour or so after smoking. In other words, under circumstances in which you are most likely stoned and have no business being behind the wheel of a car.

I can only think of two explanations for this.

1. The medical MJ activists don't know their ass from a hole in the ground. They've completely confused the tendency of THC metabolites (which is what is tested for in most employment screens) to hang around at detectable levels for days or weeks, with the active form of THC, which has a plasma half-life on the order of a couple of hours (meaning it disappears much faster), and is the standard used under I-502.Beyond that, they don't understand the very science that they cite in support of their argument.

This is the most charitable explanation.

2. Medical marijuana dispensaries are enjoying a brisk business in the gray market. Under legalization, dispensaries will be mostly redundant, with the possible exception of those that choose to operate as a non-profits to provide low-cost (or free) palliative marijuana to people in need. Not much money in that.

This is rent-seeking, plain and simple. And there is good chance it is going to kill this initiative.


Gino said...

how would this DUI test be administered? does a breathalizer work?

Brian said...

Nope, it's a blood draw. Has to be, for pharmacokinetic reasons.

Which should make the tests relatively infrequent, at least compared to alcohol tests (i.e., no checkpoints.) It'd be prohibitively expensive.

Bike Bubba said...

So there's good data on how much THC (?) leads to impairment, then? I'd been under the impression that even figuring that out was pretty much banned by law.

Brian said...

Bubba--you can do behavioral (including human) research on THC, there's just lots and lots of paperwork involved. And getting someone to pay for it isn't easy.

A lot of the work has been done in Europe and Canada as well (though it isn't easy there, either.)

As to the data itself, it isn't as clear cut as it is for alcohol, but there is some. For alcohol, 0.08 is conservative, but not ridiculously so. If you look at the relative risk of a fatal crash as a function of BAL, the inflection point where the curve starts rising very fast is 0.10. (That's a population average, of course...YMMV, but you gotta draw the line somewhere.)

That's based on data collected from tox screens of drivers in fatal crashes, and back calculating the population incidence of the BAL. I don't know the math myself, and there are a couple of assumptions there, but it holds up pretty well, and is borne out by more controlled studies (i.e., where BAL is manipulated and driving performance on a closed course or simulator is measured.)

That data set just isn't as large for THC, so it's difficult to make the same kind of quantitative predictions. In some controlled studies, certain parameters of driving performance don't seem to be negatively affected by THC at moderate doses (reaction time, risk taking behavior), and this is often cited as "THC is not as dangerous as alcohol." And it probably isn't...but it doesn't follow that it is "safe".

Subjectively, many pot smokers will tell you it isn't that hard to smoke enough to where you shouldn't drive, at least for an hour or two. Even if your hand-eye coordination remains intact, your ability to pay attention is certainly impaired. That can be hard to measure in a controlled study, but it will definitely come into play if, say, a pedestrian steps out in front of you or another car cuts you off.

The main concern about setting a hard cut-off is the variability in the rates at which people metabolize THC, and the tenuous relationship between plasma THC and impairment. Absent a large data set like we have for alcohol, I think the best thing you can do is 1) assume some impairment within the first hour or so for most people at moderate to heavy doses, 2) get a sense of what plasma THC does in that time frame, and 3) look at where plasma THC tends to be among habitual users after hours to days abstinence, when they probably have measurable levels but are not impaired. Then you set the cutoff somewhere between 2 and 3.

Without reviewing a whole lot of literature in detail (and making this comment longer than it already is), the studies I've looked at that I think were done well (and importantly, are published in decent peer reviewed journals) would indicate to me that 5 ng/ml is pretty good. It's actually not even all that conservative.