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14% Drivers with Kids in the Car Tested Positive for Cannabis

MedicalResearch.com Interview with:
Angela Eichelberger, Ph.D.
Senior Research Scientist
Insurance Institute for Highway Safety

MedicalResearch.com: What is the background for this study?

Response: Dr. Romano and Dr. Kelley-Baker have previously studied the problem of child endangerment in alcohol-related crashes. In the United States, each year, about 200 children die and another 4,000 are injured while being driven by a drinking adult.

For this study, we wanted to take the opportunity to look at the prevalence of alcohol and cannabis use among drivers who participated in a roadside survey in Washington State. To our knowledge, this is the first study to examine cannabis use among drivers transporting a child.

MedicalResearch.com: What are the main findings?

Response:  About 1 in 7 Washington drivers with children in the car recently used cannabis. We tested drivers’ blood and/or saliva for THC, the psychoactive component of cannabis. It was surprising that drivers with and without children were about equally likely to test positive for THC (14.1% vs. 17.7%). This is a different pattern than we see with alcohol. Drivers transporting children were significantly less likely to test positive for any alcohol (0.2%), compared with drivers not transporting children (4.5%).

The study also shows us that some drivers did not recognize the risk of impairment. Although most of the drivers transporting children said cannabis was “very likely” to impair driving (62.0%), some drivers said it was “not likely at all” to impair driving (6.1%).

MedicalResearch.com: What are the limitations of the study? 

Response: We don’t know how many of these drivers may have been impaired, because THC presence in blood or saliva doesn’t tell us whether someone is impaired. Also, this data was from one state (Washington), and the results may not generalize to other states, where drivers may have different patterns of alcohol and cannabis use. The surveys took place during Friday daytime hours and Friday and Saturday evenings, so the results may not be representative of other days and times.

MedicalResearch.com: What should readers take away from your report?

Response: The possibility that some of the drivers in this study were impaired is of concern. The study shows us that some drivers did not recognize the risk of impairment, yet laboratory studies have shown that cannabis use has the potential to impair driving skills.

Consumers need to know that cannabis products can be impairing. If someone is feeling the effects of cannabis, they should not drive. Different products and methods of ingestion may have different effects. For example, it takes longer to feel the effects of edible cannabis products, compared with smoking. Driving after consuming any potentially impairing substance, legal or illegal, prescription or not, puts the driver and others at risk.

MedicalResearch.com: What recommendations do you have for future research as a result of this work?

Response: Having children present seems to prevent a driver from consuming alcohol and driving. However, this research indicates that drivers consuming THC may be just as likely to drive, regardless if children are present. This suggests a need to take a look at situations beyond alcohol impairment that may put children at risk.


Eduardo Romano, Tara Kelley-Baker, Staci Hoff, Angela Eichelberger, Anthony Ramírez. Use of Alcohol and Cannabis Among Adults Driving Children in Washington State. Journal of Studies on Alcohol and Drugs, 2019; 80 (2): 196 DOI: 10.15288/jsad.2019.80.196

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Last Updated on April 26, 2019 by Marie Benz MD FAAD