Pit Bulls are no more or less dangerous than any other breed. It's how they're raised and the nature of their owners that are decide if they are or are not dangerous.
My huge dog is part lots of dogs... but a goodly part of that is pit, I know. She's strong and big... broke my leg the first time I tried to take her for a walk! But she is also loving and friendly to all who come through the front door. I do admit she's hesitant around men, but nowadays, who *wouldn't* be? It's also part of her past history. Adopted once a month every three months for 3 months in a row... and brought back as "hostile" each time. We brought her home wondering what the big foofarah was?! Her sister had been successfully adopted, but Lexy got left behind or brought back each time.
She is as protective and wary as the German Shepard and the Leonburgher dogs I used to have. But then, I give them (and my cats) lots of good food... and even more love and support than that. THAT is what makes the difference. And even tho she's part pit, part who knows what?... the CATS rule her and the house, and she knows it.
Human ignorance and cruelty... those are the biggest problems we have with ANY companion animals!