In an open letter Cavic, who took silver in the 2008 100m butterfly, says he's not calling a Phelps a drug cheat but went onto the state the American's 'recovery rate was nothing short of science fiction'.
"Doping has been a problem and it's only getting worse. I, too, don't know what to tell my son, nor would I wish that my son ever be half as good as I was knowing what he'll face tomorrow," Cavic wrote in an open letter posted on his Twitter account.
"I could recall Lance Armstrong getting tested 3x in one day, and never failed once, but that's not the problem. At the moment, we're not able to detect new drugs and advanced methods of doping. Why you're seeking reform now that you're retired, and never before supported blood passports, is beyond all of us, perhaps even convenient.
I'm not suggesting you're a cheat, you've gradually improved your times throughout your career, but your recovery rate is nothing short of science fiction....We all just wish we could understand it. Anyway, I really do hop that you'll sticks with this because in case our sons go pro some day, I;d like to think you made a difference. #nevertoolate"
