The Centers for Disease Control and Prevention are urging electric scooter riders to wear helmets and get proper training after a recent study showed just how dangerous they can be.

Over a three month period in 2018, 271 people were hurt in some type of incident. Drivers suffered head injuries in half of those crashes and 15 percent were considered traumatic.

The popularity of e-scooters from billion-dollar companies like Uber, Lyft, Lime and Bird have created a new health scare, according to the Centers for Disease control.

According to the CDC, since the surge in popularity, there has been an increase in emergency room visits for fractures, dislocations and head trauma.

“A high proportion of e-scooter related injuries involved potentially preventable risk factors, such as lack of helmet use, or motor vehicle interaction,” a preliminary summary of the study said.

The median age for people injured was 29. The majority of injuries occurred on the street, with 29% connected to first-time riders and 18% involving motor vehicles.

According to the CDC study, the most common wound after head injuries involved upper extremity fractures at 27%, followed by lower extremity fractures at 12%.

Half the people interviewed said a “surface condition like a pot hole or crack in the street” may have caused their injuries. Just over one-third of people in the survey said they would use a dockless electric scooter again.