In the race to catch drug cheats, sports officials are turning to more sophisticated tests. Since cheaters are rarely caught red-handed, scientists devised a plan to catch them with the packaging – inside their bodies - by looking for residues of a plasticizer. But the chemical is so ubiquitous that it has clouded the results of these blood doping tests in the professional cycling world. Some experts – and Tour de France champion Alberto Contador, who was found guilty of doping Monday – say that these phthalate residues are so widespread that there is doubt about how they got into an athlete's body. But others say that spikes of these chemicals are a red flag for doping.