A new yearlong study in the Journal of the American Medical Association suggests that more electric scooter riders experienced injuries than bicyclists or pedestrians, according to the data taken from two emergency rooms in Los Angeles.

The most common injuries were fractures, sprains, and head injuries. Most e-scooter companies don't include a helmet with rental, though some, like Bird and Lime, let you request one by mail-order from within their apps.

Scooter companies like Bird and Lime have brought their on-demand scooters to cities all over the world, but there isn't a lot of data to show just how safe these vehicles are (or aren't).

Since the introduction of dockless electric scooters in the Westside region of Los Angeles early last year, emergency rooms have seen an uptick of patients who have suffered injuries while riding — most of the time without a helmet.

A new yearlong study published in the Journal of American Medical Association (JAMA) offers evidence to support the concerns of health officials who have pondered the effect that dockless electric scooters, like those offered by hot startups Bird and Lime, have on public safety.

After analyzing two local Los Angeles emergency rooms, researchers found scooter riders show up with injuries more often than bicyclists or pedestrians. The main reason? Forty percent of riders came in with head injuries. Fractures (32 percent), cuts, and sprains (28 percent) make up the rest of the types of injuries.

Only 10 of the 249 people who came in with scooter injuries were wearing a helmet when the accident happened. Most scooters can reach speeds of up to 17 miles per hour. That said, California recently passed a bill allowing riders over the age of 18 to legally forgo wearing one while riding.

For comparison, the same study saw 195 ER visits for bicycle-related injuries, and 181 visits for pedestrian injuries.

If you have been to a city with dockless scooters and saw riders zooming by, chances are you have had to dodge out of the way once or twice. Yet, only 8 percent of of the scooter-related injuries tracked by the study were among non-riders — someone hit while either not paying attention or turning a corner.

The study is the first of its kind to give a quantifiable estimate of the real-world effects of the scooters on the people who ride them.

A Lime spokeswoman said in a statement to USA Today that riders are "our number one priority." Lime has $1 million in liability insurance on each ride and has given away 250,000 free helmets worldwide, it says.

A spokesperson for Bird told BuzzFeed the study "fails to take into account the sheer number of e-scooter trips taken" and doesn't contextualize the findings with injuries from automobiles or motorcycles. Bird also gives away free helmets to its riders.

E-scooters are likely to have a role in how cities find solutions for traffic congestion — and these findings can be an asset for lawmakers looking to modernize policy to keep up with this trend while keeping the public in mind.

The Centers for Disease Control are planning on expanding upon this kind of research: a team has already been sent to Austin, Texas to investigate scooter crashes in the city.