Ann Arbor has facilities for drug and alcohol detection and testing. This is usually done by obtaining a biological sample from the individual, such as the urine, hair, blood, sweat, or oral fluid / saliva. One can detect the drug or the alcohol directly, or infer its presence by the metabolites (breakdown products of a drug or the alcohol). This is used by law enforcement agencies, rehab clinics and in sports to prevent usage of performance enhancing drugs. Kits for detection may be available for sale. The accuracy of the result would vary with the time of the test and the time when the drug or alcohol was ingested, and the kind of test that can be used would also vary with the same. Labs can also do the test in Ann Arbor on being given a sample. For alcohol testing, breath-analyzers may be used. Experts such as toxicologists can provide scientific evaluation of DUI involving alcohol and drugs.