In 2000, the Razor scooter landed on the U.S. toy market and took off. The foot-powered scooter, which offered a smooth, speedy ride and was maybe even a little cooler than a bike, sold more than 5 million units in six months and was named Spring/Summer Toy of the Year by the Toy Industry Association.

But around that same time, non-fatal emergency room visits by kids associated with their beloved toys also spiked, according to a new study.

Since 1990, non-motorized scooters like the Razor and dozens of other ride-on toys currently on the market have been a driving force behind a big increase in the number of injuries that are severe enough to send kids to the emergency room.

A first-of-its-kind study by researchers at the Nationwide Children’s Hospital found that between 1990 and 2011, more than 3.2 million kids were estimated to have been sent to the ER for toy mishaps. And the rate of injury increased by 40 percent in that time.

The growth was mostly attributed to those foot-powered scooters, the authors contend.

“Much of the increase in the overall toy injury rate after 1999 is due to foot-powered scooters,” Gary Smith, the study’s senior author and director of the Center for Injury Research and Policy at Nationwide Children’s Hospital, said in a statement.” In fact, I will say that I’ve never seen anything like it in my career.”

The study, which was published in the Journal of Clinical Pediatrics on Monday, is the first to look at toy-related injuries using nationally representative data. It used ER visit data from the National Electronic Injury Surveillance System that tracks consumer product-related injuries treated in thousands of U.S. hospitals.

About half of the injuries occurred in children who were younger than 5 years old, and they were more likely to be injured by exploratory and practice play toys than older children. Children who were younger than 3 years old were also more likely to accidentally ingest or choke on toys.

But among kids 5 years and older, they were most likely to sustain injuries from playing with ride-on toys and toy weapons than younger kids. And about 77 percent of the ride on toy injuries were due to falls.

Ride-on toys — which include scooters, tricycles and toy wagons — not only lead to cuts and scratches but also broken, fractured, or dislocated limbs.

“The frequency and increasing rate of injuries to children associated with toys, especially those associated with foot-powered scooters, is concerning,” said Smith, a professor of pediatrics at Ohio State University. “This underscores the need for increased efforts to prevent these injuries to children. Important opportunities exist for improvements in toy safety standards, product design, recall effectiveness, and consumer education.”

The risks can be managed, however.

According to the study’s authors, in the years after ride-on toys such as scooters zoomed to the top of Christmas wish lists in the United States, greater public awareness of the injury risks helped bring down the injury rate after the sudden spike around 2001.

But since 2005, some of that progress appears to have eroded and the number of ride-on toy related injuries has been rising once again.

Rebecca Mond, director of federal government relations for the Toy Industry Association, said the new study further highlights the need for a continued partnership between manufacturers who are responsible for product safety and parents who supervise their children at play.

“Parents can really be assured that toys sold on U.S. shelves are safe,” Mond said in an interview. “It’s important for us as parents to also pay attention to our children when we’re playing and pay attention to age grading for toys and making sure that our children are safe when they are riding on these scooters.”

Razor USA, the company that makes the popular Razor scooter, recommends that its scooters not be used by anyone under the age of 8 without parental supervision. They also recommend using helmets and knee and elbow pads at all times.

In a statement, Katherine Mahoney, the vice president of marketing at Razor noted that the study did not compare the Razor scooter to other “competitive” ride-on toys like bikes, in-line skates and skateboards.

“That these results would skew toward scooters being associated with ‘more’ injuries is not surprising – but the point is that when compared to other competitive ride-on products, scooters are actually less risky and, even so, the rate of injuries associated with the use of a scooter is not statistically different today than it has been for years,” Mahoney said.