Incidents of drugged driving that resulted in a death in Iowa are on the rise, state law enforcement officers have told a local media outlet.

In 2017, Iowa State Patrol reported 40 deaths in drug-related collisions as compared with just 22 in 2014, reports KCRG. That would be a nearly 82% increase.

Law enforcement believes the boost in drug-impaired crashes and fatalities over the three-year span is linked to its not-too-distant neighbor, Colorado. That state legalized marijuana in 2014 and officers say they see more drugs coming into Iowa from Colorado, notes the report.

In addition to marijuana, Iowa State Patrol is finding illicit pill use on the roadways as well. 

If an officer stops a motorist who passes a Breathalyzer but still seems impaired, sometimes a drug-recognition expert is called in to determine the cause. These experts use a series of techniques to assess is a driver is abusing drugs or high on marijuana, notes KCRG.

For example, experts are trained to check a driver's eyes in different light conditions, their heart rate, as well as search for drug residue on their hands.

Rapidly changing state laws regarding marijuana are having an impact on roadway safety. Presently, some form of marijuana use is legal in the majority of states. There are only 14 states where marijuana use is completely illegal, according to DISA, a workplace drug testing service.

In Iowa, drunk driving still surpasses drugged driving. More than 370 people lost their lives in alcohol-related crashes in the state between 2014 and 2017 alone, reports KCRG.