It is pretty commonly known that labs do lead in dog bites. Here is a very recent study in CO:
But, there are also more labs as pets than other breeds, nearly 3 times as many as the next breed registered (chihuahuas) according to this article.
The difference - if a lab bites you, it is probably pretty survivable, single bite and move away. If a pit bull bites, it is probably not going to end well.
This lab was a SERVICE DOG....how often do trained SERVICE DOGS bite THEIR CLIENT. He was trained for Trig. Period.