As the presence of electric scooters continues to grow in U.S. cities, so do the safety risks that come with them.

The number of e-scooter-related emergency room visits in the U.S. has surged by nearly 450% from 7,700 in 2017 to 42,200 in 2021, according to a recent report from the U.S. Consumer Product Safety Commission. And those estimates likely represented an undercount, the federal agency added.

The vehicles can become safety hazards for many reasons, such as when they obstruct sidewalks when parked, are used by riders who are inexperienced, distracted or impaired, and when colliding with cars or pedestrians on sidewalks or roadways, according to a report published by the National Academies of Sciences, Engineering, and Medicine and the Transportation Research Board.