At my radio station last Sunday I received an API report regarding the statistics for mortality due to dog bites. The dogs cited for the highest incidents of deadly bites were the Rottweiler and the Pit Bull between the years 1991-1998.
Remember that breeding means everything in the domestic dog. If a "breeder" (and anyone with two dogs of opposite sex can call themselves that) is intending his breeding stock to produce tough, pain resistant and tenacious progeny, that "lineage" will predominantly produce such dogs. Even those who "fail" the test during young adulthood still carry the genetic predisposition for the behavior.
Is the Pit Bull dangerous? From the wrong "breeder", the likelihood increases. From a "true" breeder of the AKC recognized varieties of "Pits" (the true breeder showing in conformation and breeding to the Standard for temperament and type), it is highly unlikely that you will find a "dangerous" dog! Rescuers in this breed claim that the "sound" Pit Bull should never demonstrate aggression toward Humans.
This breed can be a charming and challenging companion, but only in the "right" hands. NEVER purchase a Pit Bull puppy from just anyone, especially NOT from newspaper ads! Be sure to meet both the dam (mother) and stud (father) of the litter and determine their friendliness. Once you have your pup, enroll in puppy kindergarten and obedience training with your dog as soon as you can. This is NOT a breed that belongs in the "average" home. It requires a firm, humane, constant leadership and lots of obedience instruction.