There are also many synthetic sex steroids. Synthetic androgens are often referred to as anabolic steroids . Synthetic estrogens and progestins are used in methods of hormonal contraception . Ethinylestradiol is a semi-synthetic estrogen. Specific compounds that have partial agonist activity for steroid receptors , and therefore act in part like natural steroid hormones, are in use in medical conditions that require treatment with steroid in one cell type, but where systemic effects of the particular steroid in the entire organism are only desirable within certain limits. 
On September 20, 2007 Floyd Landis was stripped of his title as winner of the Tour de France , and was subjected to a two-year ban from professional racing after a second test showing an elevated T/E ratio. Landis won the 17th stage of the tour; however, tests taken immediately after the stage victory showed a T/E ratio of 11:1, more than double the 4:1 imposed limit (recently lowered from prior limits of 8:1 and 6:1). On August 1, 2006, media reports said that synthetic testosterone had been detected in the A sample, using the carbon isotope ratio test CIR . The presence of synthetic testosterone means that some of the testosterone in Landis’s body came from an external source and was not naturally produced by his own system. These results conflict with Landis's public speculation that it was a natural occurrence.  Landis originally denied the charges, but in 2010 Landis admitted to doping during much of his career,  but continued to adamantly deny taking testosterone that would have led to the positive test in the 2006 Tour de France.