If athletes are willing to take these risks, and many are, then why should the world of competitive sport stop them? Anyone that doesn’t want to risk their health does not have to take performance enhancing drugs. But those that are willing to put their health at risk in exchange for improved performance should be free to decide what to put into their bodies.
Additionally, the adverse health impacts of doping pale in comparison to the risks athletes are forced to take every day, risks that are permitted in the rule book. American football players suffer concussions that can cause dementia later in life,
rugby players wear out their knees and shoulders to the point that they cannot hold their children after retirement, 
and cliff divers risk their lives every time they compete. Put into perspective, the adverse health effects of doping are relatively manageable compared to the risks that come from competing at the highest level. If sport was serious about athletes’ safety, it would look at existing rules that put players at risk, not worry about doping.