On Sunday, “60 Minutes” aired an interview with Lance Armstrong’s teammate Tyler Hamilton, in which Hamilton accused Armstrong of using the banned drug EPO for blood doping. Athletes can “blood dope” by taking drugs such as EPO to unnaturally increase their red blood cell count, hoping to increase oxygen flow and boost energy and endurance. Among other claims, Hamilton told “60 Minutes” that Armstrong convinced a Swiss anti-doping lab to keep silent about his test results. Armstrong is currently under federal investigation, and he strongly denies all charges. The consequences of EPO use, though, are not merely legal.

Cyclists who use EPO might be interested to know that in 2009, Nuno Piloto and Helena M. Teixeira of the Institute of Pharmacology & Experimental Therapeutics at Coimbra University tested the effects of EPO on lab rats. How did it go? Not very well. In Week 8, one of the rats dropped dead. Piloto and Teixera found that chronic EPO doping increased the viscosity of blood, leading to heart failure and sudden death. Erythrocytosis, or the excess of red blood cells, can also cause seizures, heart attacks and pulmonary embolisms. Counter-intuitively, Piloto and Helena suspect that EPO side effects could cause sudden death even during periods of inactivity. Along with other scientists, they believe that EPO could have been responsible for the deaths of about 20 cyclists, though scientists did not have the knowledge to prove it at the time. “Athletes who abuse rhEPO seem to consider only the benefit to performance and ignore the short and long-term side-effects,” Piloto and Teixeira wrote. It seems athletes who illegally practice blood doping have more than the authorities to worry about.