After accident with six deaths, NTSB chief underestimates the effects of marijuana on drivers

DETROIT — After a horrific traffic accident in Oklahoma two years ago that killed six high school students, the chairman of the U.S. National Transportation Safety Board (NTSB) is calling on parents to warn their teenagers about the dangers of driving after consuming marijuana.

Chair Jennifer Homendy made her appeal to parents on Thursday as her agency released the final report on the March 22, 2022 collision between a small Chevrolet Spark hatchback and a semi-trailer hauling gravel in the small town of Tishomingo.

After an investigation by its staff, the panel concluded that the accident was caused by the 16-year-old driver slowing down at an intersection and then accelerating at a stop sign because she was likely impaired by the marijuana use she had recently had and distracted by the five juvenile passengers in the car, the NTSB report said.

In an interview, Homendy also said that the cannabis problem is not limited to teens. As more states have legalized marijuana for recreational use, teens and adults tend to underestimate the risks of driving under the influence of drugs.

“There is a perception that in states where marijuana is legal, it is safe and legal to drive under the influence of marijuana,” she said.

In its report on the accident, the NTSB cited studies showing that marijuana reduces motor coordination, slows reaction time and impairs judgment of time and distance – all critical functions for driving.

According to the Insurance Institute for Highway Safety, it is currently legal for people 21 and older to use marijuana for recreational purposes in 24 states plus Washington, DC. Oklahoma does not allow recreational use, but like most states, it is legal for medical purposes. Driving under the influence of marijuana is illegal in all states and Washington, DC.

The NTSB, which investigates traffic crashes but has no regulatory authority, issued a safety alert Thursday urging parents to talk to young drivers about how marijuana can impair driving ability and how they can make responsible decisions to avoid driving while impaired or riding with impaired drivers.

Homendy said states that have legalized marijuana are lagging behind when it comes to making it clear to people that it is illegal to drive while under the influence of marijuana. More than half of Americans live in a state where recreational use of cannabis is legal, she said.

“Unfortunately, I believe that the state laws legalizing recreational and medical use of marijuana were actually passed before any consideration or action was taken on traffic safety,” Homendy said. “They’re way ahead on legalization, but way behind on traffic safety.”

She believes states need to collect more data on how marijuana legalization has affected road safety and start enforcing laws against driving under the influence of cannabis.

“To deter, appropriate enforcement measures must be taken,” she said.

A study of traffic accidents in Washington state, where recreational marijuana use is legal, showed that more drivers involved in fatal crashes tested positive for marijuana after marijuana was legalized, the NTSB said.

In Tishomingo, about 100 miles southeast of Oklahoma City, six high school students got into the four-person car for their lunch break, the NTSB report said.

At an intersection, the driver slowed to 1 mph but accelerated and did not stop at a sign. Instead, she accelerated and turned left in front of the gravel truck. The truck driver braked and steered to avoid the Spark, but crashed into the driver’s side at nearly 50 mph (80 kilometers per hour). All six teens died from multiple blunt force injuries.

Blood tests taken from the driver’s body found a concentration of THC of 95.9 nanograms per milliliter, the NTSB said. If such a level of THC, the main component of marijuana, were found in a living person, it would “indicate with a high degree of probability that the person had only recently used cannabis and therefore is likely still suffering from the acute, impairing effects of cannabis,” the report said.

However, the NTSB cautioned that blood samples from body cavities can sometimes be contaminated by other body fluids or by THC from other tissues, including the lungs, which can contain high concentrations.

In addition, the Oklahoma Highway Patrol found vaping mouthpieces and cannabis flowers in the car at the scene of the accident, the report said.

The NTSB recommended in the report that the Oklahoma State Department of Education develop a drug and alcohol abuse curriculum for local school districts that educates students about the risks of driving under the influence of cannabis. Currently, only Massachusetts and Rhode Island have such course requirements, according to the NTSB.

The agency also wants the Governors Highway Safety Association, a group of state highway safety officials, the National Conference of State Legislatures and the National Association of State Boards of Education to educate their members about the Tishomingo accident and the need for information about cannabis in schools and driver’s education classes.

In a statement, the safety association said that driving under the influence of cannabis is a growing safety risk and that state traffic safety authorities are committed to preventing driving under the influence of cannabis in any form.

“We need to make it clear to children well in advance that driving or using, smoking or inhaling marijuana impairs their performance and poses a risk to themselves and others,” Homendy said.