A number of high-profile positive tests in the United States, among them Amir Khan's conqueror last December Lamont Peterson, have led to fears that doping is widespread.
Much closer to home, British heavyweight Larry Olubamiwo admitted to using 13 banned substances and claimed a "large minority, if not majority, of boxers are doping".
But Mitchell, who will challenge for British rival Ricky Burns' WBO lightweight title in Glasgow on September 22, denies the sport has a problem.
"It's a myth more than anything, it's not a massive thing over here," the 27-year-old said.
"I don't know about America, but here it's a not a problem. I know a lot of fighters over here and it doesn't happen. But America's a different place.
Promoter Frank Warren questions the rapid rise through the weight divisions by fighters based in the US.
"If Ricky or Kevin were Americans they would be fighting at light-welterweight or welterweight now," he said.
"I don't see how the guys in America can go through the weight divisions like they do. It doesn't happen like that in Europe, so who knows?
"The fact of the matter is over here there are strict drug testing standards.
"Every boxer is tested prior to the fight and on the night. Fighters know what's at stake."
Burns will be making the second defence of his world crown and Mitchell is full of respect for his opponent.
"Ricky's a great fighter but people have a habit of overlooking him. They think he's good, but he isn't great," he said.
"He got beaten earlier in his career but that can happen to anyone. He's really come on so much since then.
"As a fighter his defence is unbelievable. He always does enough. He doesn't go mad and over the top. If you overlook him, you're in trouble."