Dr. Gary A. Smith, who directs the Center for Injury Research at Policy at Nationwide Children's Hospital in Columbus, Ohio, told NBC News no one studies how many grownups are hurt or killed on amusement park rides.
Last week, a woman, Rosy Ayala-Goana, died after she fell from the Texas Giant roller coaster at the Six Flags Over Texas amusement park.
"We don't have a really good system for catching all of these [injuries]," Smith said. "Many of these go unmonitored and unaddressed."
Smith published a study this year tracking kids younger than 18 who are hurt on roller coasters, carnivals and kiddie rides.
He found about 4,400 children are hurt on such rides each year, though only about 67 require hospitalization, and suspects a similar number for adults would be found if anyone conducted such a study.
To do so they would have to review data from U.S. emergency department reports, Smith said.
The International Association of Amusement Parks and Attractions says about 297 million people safely rode 1.7 billion rides in the United States in 2011, NBC reported in May.
A 2005 report by the Consumer Product Safety Commission showed 52 deaths were linked to amusement rides between 1990 and 2004. A spokesman told the network no later figures were available.