Fatal crashes involving drugs tended to occur during daylight hours while alcohol-related collisions were more common on weekends and late at night, researchers found. (CBC)

Drug use by drivers is nearly as common as alcohol use, new Canadian research suggests.

A study of more than 14,000 driver fatalities in the country from 2000 to 2006 by the Canadian Centre on Substance Abuse found 33 per cent of drivers tested positive for at least one drug and 38 per cent tested positive for alcohol.

The most common drugs found in the blood of the drivers were:

• Depressants.
• Stimulants.
• Cannabis.

Fatal crashes involving drugs tended to occur during daylight hours throughout the week while alcohol-related collisions tended to happen on weekends and late at night, the researchers found.

A second study presented this week at the International Council on Alcohol, Drugs and Traffic Safety in Oslo analyzed early results of a roadside survey of 1,500 drivers who tested positive for drugs or alcohol in British Columbia in June.

About 10 per cent of drivers tested positive for drug use and eight per cent tested positive for alcohol, Douglas Beirness, the group's senior research and policy analyst, found. Cannabis and cocaine were the most common drugs.

Awareness campaign urged

"Illegal, prescription and some over-the-counter drugs can have serious effects on a variety of mental and motor abilities," Beirness said.

"As many of these abilities are critical to the safe operation of a motor vehicle, there is a real need for an impaired-driving awareness campaign that is inclusive of both alcohol and drugs," he added in a release.

A federal law that came into effect in July 2008 gave police new powers to conduct mandatory roadside tests on drivers suspected of being impaired by drugs.

A third study presented by Amy Porath-Waller, senior research and policy adviser with the Canadian Centre on Substance Abuse, analyzed assessments conducted by police with the aim of identifying key signs and symptoms to predict the types of drugs used by suspected drug-impaired drivers.

Indicators related to the eyes seemed be particularly informative in accurately assessing drug impairment, Porath-Waller found.

Drug-impaired driving arrests last year rose to 1,394 from 441 the year before, according to Statistics Canada. Of the nearly 89,000 incidents of impaired driving in 2009, about two per cent were for drug-impaired offences, the agency said.

The centre has a legislated mandate to reduce alcohol- and other drug-related harms and receives funding from Health Canada.