(drug screen)
It is possible to detect the presence of alcohol, other drugs affecting the central nervous system, and drugs used to enhance athletic ability by a variety of tests. Body material such as urine, blood, exhaled air and hair can be analyzed by instruments capable of detecting minute concentrations of drugs or their breakdown products. Another commonly used type of test measures the physiologic effect of the drug, as for example when a law enforcement officer requires a suspect to walk on a straight line to detect alcohol intoxication.