Road accident chances doubled by pot smoking, says US survey
According to a New York university, drivers who test positive for cannabis run double the risk of being involved in a road accident
compared to 'clean' drivers.
Researchers from Columbia University's Mailman School of Public Health added that over 10 million individuals aged at least 12 are thought to have driven under the influence of illegal drugs
in the USA during the last 12 months.
Researchers explained that, of non-alcohol drugs, cannabis is the most commonly detected in drivers
. However, it is unclear what impact this has on road accidents.
Looking to determine if cannabis use and vehicle accident risk are linked, the team under Dr Guohua Li conducted a study of 9 previous epidemiologic studies.
The team found that people who tested positive for cannabis, or were reported having recently used the drug, ran more than twice the risk of a road accident compared to those who had consumed neither drugs nor alcohol.
The researchers also noted that levels of cannabis in urine and risks of crashing were related - the higher the drug quantity, the greater the risk.
8 out of the 9 studies found that cannabis users are "considerably" more likely to crash their vehicles than non-users. The exception was one small study carried out in Thailand, where use of cannabis is comparatively low.
In 28% of driver fatalities the driver tested positive for non-alcohol drugs. Over 11% of the general driving population (regardless of accidents) tested positive to non-alcohol drugs, of which cannabis was the most common detected.Susan Vanden of Simpson Millar LLP
warned that, despite evidence that drug consumption is related to crash risk, the university's findings need to be confirmed by real cases over a longer period of time, both in the US and the UK.
"However," she said, "if further research in Britain reveals that the US team is on the right track, such findings should be used to shape government policies on driving safely, as well as on the use of cannabis in the medicinal context."