With two American states legalising the possession and recreational use of spliff, this is becoming an important question to ask.  Especially as, according to a new survey from the  California Office of Traffic Safety, there are more stoned drivers on Californian roads than drunk ones.

1 300 drivers were tested in nine Californian cities on Friday and Saturday nights, 14% were found to have drugs in their system, while only 7,3% were found with alcohol, spliff was ever so slightly higher at 7,4%.

How The Atlantic Wire worked out the maths to lead with a headline of “California Drivers are Twice as Likely to be High Than Drunk” we just don’t know. Those numbers suggest only two more people were stoned. This, naughty Esther Zuckerman, does not mean twice as likely. Tsk. Tsk.

But the important question is out of those 14% intoxicated Californian drivers, who drives better?

The funny thing is that in the US, officially, no one is quite sure. Maia Szalavitz, a neuroscience journalist writing for for TIME.com reported on the same study and said:

While marijuana does not promote uninhibited and potentially reckless behavior like alcohol does, THC does have mild hallocinogenic and sedative effects, and studies show it can impair cognition and memory, making driving potentially more hazardous.

But:

Because of the scientific controversy over the link between marijuana fluid levels and impairing effects, few states have set standards for stoned driving detection. Colorado has debated  them but legislators cannot come to an agreement.

Everyone is pretty confused. Essentially the problem arises over the way to test for THC levels. While studies have indicated that going for a drive within three hours of having a spliff increases the chance of a fatal accident by 92%, THC can stay in a users system for varying times. THC can be picked up in a toker’s blood up to a week after smoking, and outer limit of detection time in saliva tests is not known.

In a separate article Szalavitz wrote:

Interestingly, researchers have also found that states that legalize medical marijuana have fewer fatal car crashes, largely because of a decline in drunk driving. In other words, people may be substituting marijuana for alcohol — and while it’s not advisable to drive under the influence of either — the net result, when it comes to traffic deaths, could be a reduction in harm because smoking pot raises the crash risk less than drinking does.

With Colorado and Washington legalising recreational marijuana use, the US is going to have to conduct far more research into understanding marijuana’s effects on decision-making while driving. It is going to be interesting to see the results, and if they line up with the common belief that smoking a spliff and driving is less dangerous than driving after a couple drinks.

[Sources: The Atlantic Wire, TIME.com]