According to a roadside survey conducted in Washington State, 14.1% of drivers with children in the car–nearly one in seven–tested positive for THC, the principal psychoactive compound in marijuana. The results are published in the latest issue of the Journal of Studies on Alcohol and Drugs.
The study involved data analysis from a roadside survey of more than 2,000 drivers age 21 and older conducted in Washington State in 2014 and 2015, after the legalization of recreational marijuana sales. During both daytime and nighttime hours, researchers asked drivers at stop lights and stop signs to volunteer for the study. They obtained breath, blood, and saliva samples from the volunteers and noted if children were present in the car. Additionally, they surveyed the drivers about their attitudes regarding substance use.
The study showed that when drivers had a child in the car, it seemed to affect their choice to drive while impaired by alcohol (that is, have a breath alcohol concentration over 0.08%). No study volunteers with a child in the car had breath alcohol concentrations above 0.08%. However, nearly 1% of those without children in the car were above this legal limit.
The presence of a child in the car did not appear to coincide with whether drivers had THC in their system. More than 14% of drivers with a child in the car tested positive for THC, but so did 17.7% of drivers without a child in the car, which is not a statistically significant difference.