There are more than 12,000 prescription drugs and 100,000 over-the-counter drugs in use today. Many of these cause side effects which can be dangerous on the job. For example, antidepressant drugs such as Prozac and Zoloft can cause drowsiness, dizziness, blurred vision, and tremors. These drugs are used by millions of Americans. Over-the-counter antihistamines, used by millions without prescription, have the following listed side effects -
"drowsiness, sedation, dizziness, faintness, disturbed coordination, lassitude, confusion, restlessness, excitation, tremor, seizures, headache, insomnia, euphoria, blurred vision, hallucinations, disorientation, disturbing dreams/nightmares, schizophrenic-like reactions, weakness, vertigo, hysteria, nerve pain, and convulsions. Overdoses may cause involuntary movements. Other problems have been reported."(Gale Encyclopedia of Medicine).
Performance can also be impaired without any substance use at all. Fatigue is estimated to cause over 100,000 highway accidents with 1,500 deaths per year. Distraction due to back pain is a leading cause of workplace accidents. Emotional and financial distress can also cause temporary impairment.
Drug testing looks for evidence of use of a small number of illegal drugs, and ignores the hundreds of thousands of other possible causes of impairment. Drug testing does not look for people who are impaired, it looks for people who use the "bad" drugs.
On the other hand, a positive drug test does not mean that the person is impaired, or even that the drug itself is present in the body. Many drug tests search for metabolites - waste products of drugs - rather than the drug itself. Metabolites of alcohol are detectable for about 24 hours. Intoxicating effects of marijuana wear off in 4 to 8 hours, but its metabolites can be detected for up to a month after use
There is no good evidence that drug testing improves work performance, measured by absenteeism, tardiness, productivity or on-the-job accident rates. Courts have often ruled against drug testing because the employer could not show a connection between testing and job performance. Accurate drug tests are expensive, and inaccurate drug tests lead to legal and other problems. Since drug testing is not clearly related to performance, it is seen by many employees as an invasion of privacy. Because of this it can lead to employee relation problems including difficulty in hiring, increased grievance rates, and deteriorating labor-management relations.
All of the difficulties with drug testing are solved if we simply test for what we claim to be interested in – actual current alertness or its opposite, impairment. This is called “impairment testing”, “alertness testing”, or “direct performance testing”. These tests are simple and come in many forms.
All of the difficulties with drug testing are solved if we simply test for actual current alertness. True impairment testing is inexpensive, effective, and non-controversial.
“Impairment testing is the practice of determining which workers in safety sensitive positions put themselves and others at risk by directly measuring workers' current fitness for duty. Urine testing, in contrast, attempts to determine which workers have used specific substances .... impairment testing improves safety, is accepted by employees, and is generally superior to urine testing.”
United Kingdom Department of Trade and Industry
“Obviously, people who are responsible for others' lives should be held to high standards of job performance. But urine testing will not help employers do that because it does not detect impairment. If employers in transportation and other industries are really concerned about the public's safety, they should abandon imperfect urine testing and test performance instead. Computer assisted performance tests already exist and, in fact, have been used by NASA for years on astronauts and test pilots. These tests can actually measure hand-eye coordination and response time, do not invade people's privacy, and can improve safety far better than drug tests can.”