In 1987, a national testing laboratory found that 18.1 percent of all workers tested had positive results. By 1997, that figure was down to 5.4 percent. Experts debate whether this means drug use has fallen, or drug abusers simply avoid employers that test and instead apply at firms that do not. The majority of drug testing is done by sending an applicant to a collection site, where a urine sample is obtained and sent to a certified laboratory for analysis. Negative results are normally available within 24 hours.
Some employers use instant test kits that are similar in operation to a home pregnancy test.
New testing methods, such as hair testing and saliva testing are also being used. Some employers use a 10-panel test, which includes prescription drugs that are legal to possess and use. Employers can also test for blood alcohol levels. Although each drug and each person is different, most drugs will stay in the system about two to four days. For chronic users of certain drugs, such as marijuana or PCP, results can be detected for up to 14 days, and sometimes much longer.