While it is a prescription or over-the-counter drug in 22 countries, chondroitin is regulated in the U.S. as a dietary supplement by the Food and Drug Administration. In Europe, chondroitin sulfate formulations are approved as drugs with evidenced efficacy and safety demonstrated by clinical trials in people with osteoarthritis. Adebowale et al. reported in 2000 that of 32 chondroitin supplements they analysed, only 5 were labeled correctly, and more than half contained less than 40% of the labeled amount. With the introduction of GMP regulations for dietary supplements in 2008, chondroitin sulfate preparations are subject in the US to mandatory labeling standards as well as testing requirements for identity, purity, strength, and composition. United States Pharmacopoeia (USP) testing standards for the identification and quantification of chondroitin are well-established.