Taking a walk may have deadly consequences, and the risk appears to be greater in those states that have legal adult use of recreational marijuana. The rate of fatal injury to pedestrians has grown faster than any other vehicle-related deaths for the years of rapid legalization of marijuana.

That rate increased 27 percent between 2007 and 2016, while other types of traffic deaths had decreased by 14 percent. While a direct relationship to marijuana use cannot be determined, other sources indicate that the use of marijuana is likely a factor when the driver of a vehicle is using cannabis.

Another probable major contributor to the alarming statistic is distracted driving and pedestrian mobility with cellphone use. The good news is that the report showed that, at least for the data available in 2017, the upward tick of fatal injury to pedestrians may not be continuing.

The state with the highest pedestrian fatality rate per capita for 2016 was New Mexico, and the state with the lowest was Nebraska. The state with the highest rate for the first half of 2017 was Arizona, and Hawaii was the lowest.

The majority of deaths have been on local streets. Nationally, less than 20 percent of pedestrian fatalities are at an intersection, with 72 percent being in travel lanes away from intersections and 10 percent on shoulders or driveways.

However, several states report high rates of fatal injury at intersections; New York, 33 percent; Oregon, 32 percent; Minnesota, 30 percent; Washington, D.C., 30 percent; Colorado, 29 percent; and Washington state, 28 percent. That three of these states and Washington, D.C., have a high rate of intersection death may or not be related to their having a longer history of legal recreational use of cannabis for adults. It will be important to continue to monitor the data to determine this.

The state of Washington undertook an extensive study of fatal injury related to impaired driving that spanned before, during and after adult usage of marijuana became legal.

The data demonstrate that if a driver involved in a fatal crash tests positive to active marijuana alone, and no other drugs or alcohol, they are more likely to have killed someone other than themselves at a significantly higher rate than someone testing positive for alcohol alone. The drivers positive for active marijuana alone, indicative of recent use within a few hours, were more likely to have inflicted fatal injury to pedestrians, bicyclists, other drivers or passengers.

Colorado reports an increased rate of fatal injury to pedestrians and bicyclists when the driver tests positive for only active cannabis. The contribution of a pedestrian having used marijuana and contributing to their own fatal injury is not known.

The impact of cannabis on driving performance requires extensive study, and the available research on humans is very limited. There is research demonstrating changes in the visual system with both chronic and acute marijuana use. If a driver does not see a pedestrian or does not see them accurately, this creates an increased risk for fatal injury.

The deficit in visual processing with marijuana use is the primary focus of our research. While our data is currently limited, others have identified deficits in the functioning of the eye’s retinal ganglion cells with chronic use. This was reported in the Journal of the American Medical Association last year.

The same group found dysfunction with acute use. Projects undertaken at the University of California, Berkeley in the 1970s found that the ability to recover from glare was diminished with acute use of cannabis. The horizontal peripheral visual field meridian was found to be reduced with acute marijuana use in a different study.

Visual deficits that are caused by marijuana use warrant further consideration as a means to determine functional impairment with cannabis use.

The innocent victims, pedestrians and bicyclists, deserve this attention. The topic of cannabis-impaired driving is complex and there are passionate opinions on both sides of the controversy. What is clear is that further and extensive research is warranted.