There are plenty of statistical studies out there that pit bulls specifically cause both a significant plurality of dog bites and significantly worse injuries than other dog breeds.
The word "pit" in "pit bull" refers specifically to a dog fighting arena where dogs are supposed to aggressively fight each other in a duel, possibly until one of them dies.
"pit bull" refers to a dog breed that was optimized for its performance (=more aggressive and dangerous) in the "pit".
For example:
https://blog.dogsbite.org/2016/10/table-retrospective-level-...
https://www.dogsbite.org/dog-bite-statistics-studies-level-1...