In case you haven’t noticed, there’s a public transportation revolution currently underway. Yes, apps like Uber and Lyft have made on-demand ride-hailing a reality, but more personal options like e-bikes and electric scooters are now crowding the sidewalks of many cities around the globe. They can be incredibly convenient, but are they safe? A new study suggests that there are some pretty serious health risks associated with these new transportation options.

The research, which will be published in the journal Injury Prevention, examined the rate of injuries from e-bikes and electric scooters over a period of 17 years from 2000 to 2017. The data shows that injuries from these types of electric “vehicles” are common, but it’s the types of injuries associated with scooters and e-bikes that are perhaps the most interesting aspect of the research.

As CNA reports, individuals who were injured while riding an e-bike were more likely to suffer internal injuries. These types of injuries can be quite serious, and the rate of hospitalization for people injured while riding an e-bike was higher than that of scooters. Accidents on e-bikes were also more likely to involve a pedestrian, suggesting that since e-bikes often move at higher speeds, there’s a greater risk of collisions with moving objects (and people).

But that doesn’t mean that electric scooters are in the clear. In fact, the data shows that individuals who were injured while riding an electric scooter were significantly more likely to sustain a concussion as a result. As we’ve learned more and more about the potentially long-lasting effects of head trauma in recent years, our understanding of concussions has grown. Put simply, they are to be avoided at all costs. On top of that, accidents on electric scooters were also more likely to result in broken bones.

None of this should be enough to scare you off of taking advantage of these kinds of transportation options, but it’s worth keeping in mind and it’s a nice reminder to be safe out there.