14 percent of Washington drivers with kids in the car test positive for marijuana

A roadside survey of over 2,000 drivers from across the state found that 1 in 7 adults tested positive for THC while transporting a child.

Drivers were asked at stop signs if they would be tested for alcohol and cannabis.

Less than 1 percent of drivers with children tested positive for alcohol.

But those with THC: 14 percent.

Staci Hoff is with the Washington Traffic Safety Commission and co-authored the study. She said kids act as a deterrent to drunk driving, but not for marijuana use.

"There was no difference between drivers transporting children and those not transporting children," she said.

The study was conducted by the Insurance Institute for Highway Safety from 2014 to 2015 in six counties, and published in the Journal of Studies on Alcohol and Drugs.

It made no judgment on drivers' impairment -- just whether alcohol or THC were found in their systems. THC can be detected in a person's system for weeks after use, depending on the test used. The study collected breath, blood and oral fluid samples.

It found that those with THC said they don't believe it's a risk to their driving.

"It's pretty safe to say that there is some elevated level of risk associated with driving after recent marijuana use," Hoff said.

With ride shares and transit, Hoff said there's no reason to drive high — especially with kids.