A survey by the California Office of Traffic Safety (OTS) has definitively proven that if you want to come up with scary numbers about drug and alcohol use among drivers, the best time to question them is on a Friday or Saturday night during roadside police checks.

Around 14% of the drivers tested at sites in nine state jurisdictions showed positive results for drugs―legal and otherwise―nearly double the number (7.3%) for alcohol. Marijuana was the drug of choice, showing up in 7.4% of participating drivers. The tests analyzed for nearly 50 drugs, including cocaine, opiates, amphetamines and barbiturates. 

The findings prompted OTS Director Christopher J. Murphy to warn: “These results reinforce our belief that driving after consuming potentially impairing drugs is a serious and growing problem.”

The study’s conclusion was less adamant about its findings, offering them up as merely a starting point for future studies. The “baseline California prevalence estimate for alcohol and drug use among nighttime weekend drivers and can be compared with results of future surveys to examine patterns of change in drug and alcohol use in that population.”

The National Highway Transportation Safety Administration has reported that 30% of California drivers killed in accidents in 2010 tested positive for legal and/or illegal drugs.

The population tested and surveyed by OTS was not a statistically valid representation of the state’s drivers: 61% were male, 39% female; 44% were in the 21-34 year age group, 24% were 35-49; 59% identified themselves as white, 11.1% as Asian, 8.8% as African-American, and 23.7% as other. Forty-five percent of all drivers were identified as being of Hispanic/Latino descent.

Just over 26.1% of the drivers initially approached were in Modesto, followed by Ontario (14%), Gardena (11.9%), Chula Vista (10%), Redding (9.7%), Anaheim (9.6%), Eureka (8.2%), Fresno (5.9%) and San Rafael (4.7%).  

Around 81% of the 1,699 eligible drivers pulled over voluntarily agreed to participate in the federally funded study. Ineligible drivers included those who spoke a language other than English or Spanish, or were too intoxicated.

A safe ride home was arranged if the driver had a blood alcohol concentration of .05 or higher. Participants remained anonymous and the study makes no mention of traffic tickets or incarceration. Around 84.3% provided a breath sample, 80.9 filled out the survey and 77.3% surrendered oral fluid. 

Officers used a passive alcohol sensor devise (PAS) and preliminary breath test (PBT) to do the initial testing. Participants were then offered $20 for an oral fluid sample. They filled out a questionnaire about past use of illegal, prescription, and over-the-counter drugs, and when the most recently took them.

–Ken Broder

To Learn More:

More Californians Driving High than Drunk on Weekends, Study Says (by Wesley Lowery, Los Angeles Times)

Survey of California Drivers Shows Fourteen Percent Testing Positive for Drugs (Office of Traffic Safety) (pdf)

Results of the 2012 California Roadside Survey of Nighttime Weekend Drivers’ Alcohol and Drug Use (Office of Traffic Safety) (pdf)