Driving Under The Influence of Marijuana
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Driving Under The Influence of Marijuana
Posted by CN Staff on February 17, 2014 at 13:31:12 PT
By Maggie Koerth
Source: New York Times
USA -- If you are pulled over on suspicion of drunken driving, the police officer is likely to ask you to complete three tasks: Follow a pen with your eyes while the officer moves it back and forth; get out of the car and walk nine steps, heel to toe, turn on one foot and go back; and stand on one leg for 30 seconds. Score well on all three of these Olympic events, and there’s a very good chance that you are not drunk. This so-called standard field sobriety test has been shown to catch 88 percent of drivers under the influence of alcohol. But it is nowhere near as good at spotting a stoned driver.
In a 2012 study published in the journal Psychopharmacology, only 30 percent of people under the influence of THC, the active ingredient in marijuana, failed the field test. And its ability to identify a stoned driver seems to depend heavily on whether the driver is accustomed to being stoned. A 21-year-old on his first bender and a hardened alcoholic will both wobble on one foot. But the same is not necessarily true of a driver who just smoked his first joint and the stoner who is high five days a week. In another study, 50 percent of the less frequent smokers failed the field test. As more states legalize medical and recreational marijuana, distinctions like these will grow more and more important. But science’s answers to crucial questions about driving while stoned — how dangerous it is, how to test for impairment, and how the risks compare to driving drunk — have been slow to reach the general public. “Our goal is to put out the science and have it used for evidence-based drug policy,” said Marilyn A. Huestis, a senior investigator at the National Institute on Drug Abuse. “But I think it’s a mishmash.” A 2007 study found that 12 percent of the drivers randomly stopped on American highways on Friday and Saturday nights had been drinking. (In return for taking part in the study, intoxicated drivers were told they would not be arrested, just taken home.) Six percent of the drivers tested positive for marijuana — a number that is likely to go up with increased availability. Some experts and officials are concerned that the campaign against drunken driving has not gotten through to marijuana smokers. “We’ve done phone surveys, and we’re hearing that a lot of people think D.U.I. laws don’t apply to marijuana,” said Glenn Davis, highway safety manager at the Department of Transportation in Colorado, where recreational marijuana use became legal on Jan. 1. “And there’s always somebody who says, ‘I drive better while high.’ ” Evidence suggests that is not the case. But it also suggests that we may not have as much to fear from stoned driving as from drunken driving. Some researchers say that limited resources are better applied to continuing to reduce drunken driving. Stoned driving, they say, is simply less dangerous. Still, it is clear that marijuana use causes deficits that affect driving ability, Dr. Huestis said. She noted that several researchers, working independently of one another, have come up with the same estimate: a twofold increase in the risk of an accident if there is any measurable amount of THC in the bloodstream.The estimate is based on review papers that considered the results of many individual studies. The results were often contradictory — some of the papers showed no increase in risk, or even a decrease — but the twofold estimate is widely accepted. The estimate is low, however, compared with the dangers of drunken driving. A recent study of federal crash data found that 20-year-old drivers with a blood-alcohol content of 0.08 percent — the legal limit for driving — had an almost 20-fold increase in the risk of a fatal accident compared with sober drivers. For older adults, up to age 34, the increase was ninefold. The study’s lead author, Eduardo Romano, a senior research scientist at the Pacific Institute for Research and Evaluation, said that once he adjusted for demographics and the presence of alcohol, marijuana did not statistically increase the risk of a crash. “Despite our results, I still think that marijuana contributes to crash risk,” he said, “only that its contribution is not as important as it was expected.” The difference in risk between marijuana and alcohol can probably be explained by two things, Dr. Huestis and Dr. Romano both say. First, stoned drivers drive differently from drunken ones, and they have different deficits. Drunken drivers tend to drive faster than normal and to overestimate their skills, studies have shown; the opposite is true for stoned drivers. “The joke with that is Cheech and Chong being arrested for doing 20 on the freeway,” said Mark A. R. Kleiman, a professor of public policy at the U.C.L.A. School of Public Affairs. Dr. Huestis also found that in laboratory studies, most people who were high could pass simple tests of memory, addition and subtraction, though they had to use more brainpower than sober people who passed the same tests. People who were drunk were much more likely to fail. The deficits of being stoned really began to show up, she said, when people had to handle multiple tasks at once and were confronted with something unexpected. “It’s typical to see a young adolescent with three or four other kids in the car,” she said of stoned driving. “He’s aware he might be impaired, so he’s driving carefully. “But then he sees an old man in the middle of the street. All his senses say, ‘This guy is there but will be out of way by the time I get there.’ But then the old man drops his keys and he’s slower than the kid expected. By the time it takes to process a change in the situation, there’s an accident.” Another factor is location. A lot of drinking is done in bars and clubs, away from home, with patrons driving to get there and then leaving by car. By contrast, marijuana smokers tend to get high at home. There is a lot of debate about how best to prove that drivers under the influence of THC are too intoxicated to drive. Blood-alcohol content can be reliably tested on the side of the road with a Breathalyzer, and ample data link rising levels of blood alcohol to decreases in driving skills. The same is not true for marijuana. THC levels must be measured from blood or urine samples, which are typically taken hours after an arrest. Urine tests, which look for a metabolite of THC rather than the drug itself, return a positive result days or weeks after someone has actually smoked. Yet most states have laws that equate any detectable level of THC metabolite in urine with detectable levels of actual THC in blood, and criminalize both. Only six states have set legal limits for THC concentration in the blood. In Colorado and Washington, where recreational use has been legalized, that limit is five nanograms per milliliter of blood, or five parts per billion. The problem, Dr. Huestis said, was that studies from Europe suggested that this limit was far too high. Ninety percent of impaired-driving cases in Sweden would be missed at that level, she said. The studies indicated that a better limit would be just one nanogram per milliliter, she said. But because THC builds up in fatty tissue and is released slowly over time, such a limit would ensnare frequent users who may not actually be high. Indeed, if you smoke often enough, your blood-THC content might still be five nanograms per milliliter a day after you last lit up. All of these facts lead experts like Dr. Romano and Dr. Kleiman to believe that public resources are better spent combating drunken driving. Stoned driving, they say, is best dealt with by discouraging people from mixing marijuana and alcohol — a combination that is even riskier than alcohol alone — and by policies that minimize marijuana’s risk on the road. For instance, states that legalize recreational marijuana, Dr. Kleiman said, should ban establishments like pot bars that encourage people to smoke away from home. And Dr. Romano said that lowering the legal blood-alcohol concentration, or B.A.C., to 0.05 or even 0.02 percent would reduce risk far more effectively than any effort to curb stoned driving. “I’m not saying marijuana is safe,” he said. “But to me it’s clear that lowering the B.A.C. should be our top priority. That policy would save more lives.”Source: New York Times (NY)Author: Maggie KoerthPublished: February 17, 2014Copyright: 2014 The New York Times CompanyContact: letters nytimes.comWebsite:  -- Cannabis Archives 
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Comment #6 posted by Sam Adams on February 18, 2014 at 16:04:10 PT
Of course the NY Times makes no mention of DUI from prescription drugs, which is a rampant problem.Expensive drinks and pills from the doctor are the way the elite get high on drugs.  How interesting it would be - to have a big study that compare cannabis with alcohol, benadryl, Prozac, Ambien, Lunesta, Robitussin, Sudafed, Benzoprenes, need I go on? 
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Comment #5 posted by schmeff on February 18, 2014 at 09:08:12 PT
Test Bias
"There is a lot of debate about how best to prove that drivers under the influence of THC are too intoxicated to drive."There SHOULD be a lot of debate about such a biased premise. Note that it isn't a matter of seeing what, if any, influence THC has on driving ability, but rather, how to "best" prove that THC has a negative impact. In other words, the results are predetermined. Now the only question is how to make sure the test results point to the required outcome.
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Comment #4 posted by Hope on February 18, 2014 at 09:02:17 PT
Quite interesting.
"New York State voters are divided on their own use of marijuana, as 46 percent say they've tried it and 51 percent deny they have. Women deny trying marijuana 58 - 39 percent, while men admit trying it 54 - 43 percent. Voters 18 to 29 percent admit lighting up 55 - 42 percent while voters over 65 years old deny it 69 - 28 percent."
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Comment #3 posted by Hope on February 18, 2014 at 08:59:46 PT
Comment 2
That's actually a very interesting poll they took there.
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Comment #2 posted by FoM on February 18, 2014 at 05:22:56 PT
Poll: New York Voters Back Medical Marijuana 
February 17, 2014 - New York Voters Back Medical Marijuana 10-1, Quinnipiac University Poll Finds; Strong Support For Recreational Marijuana Also 
 New York State voters support 88 - 9 percent the legalization of medical marijuana, with overwhelming support from every group, according to a Quinnipiac University poll released today. 
Voters also support 57 - 39 percent the legalization of small amounts of marijuana for personal use, the independent Quinnipiac (KWIN-uh-pe-ack) University poll finds. Poll:
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Comment #1 posted by HempWorld on February 17, 2014 at 16:02:13 PT
What is the purpose of all of this? Catching people who are stoned or catching drivers that are unfit to drive because they are under the influence of alcohol, prescription drugs and/or marijuana?I also keep seeing and hearing this erroneous statement that, if it's legal, more people will use it.Here is reality: Amsterdam had, in its early years, about 2,000 'coffee shops' now it is more like 600-700, because of policies.When you check the statistics on marijuana use in the Netherlands you will find that the use rate is about 1/4 to 1/3 that of the US (this is a direct result of prohibition on marijuana/cannabis because it acts as advertising)This usage rate has remained fairly constant over the years and may even have dropped because marijuana/cannabis has lost its forbidden fruit status.
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