Drug testing has become a big part of occupational medicine in recent years. Many employers have started drug-free workplace programs, either by choice or because of government regulation. Drug testing is often used for preemployment screening because it is not considered a medical exam and so it is permissible under the Americans with Disabilities Act.

Procedures and regulations differ according to the specimen being tested. The most important legal distinction is whether the test is regulated by the U.S. Department of Transportation (DOT). DOT has been the leading agency for drug testing. There are elaborate rules governing how the test is done and how the results are used. The very large volumes of tests done every year allow the DOT to discover and respond to legal and technical problems quickly. The simplest and best way to operate a drug testing program is to follow DOT procedures for unregulated as well as regulated testing.

It is wise to use DOT-certified laboratories for all testing as well. These laboratories do large volumes of drug tests so they can be quite inexpensive. They are carefully regulated and the system is designed to prevent false positives: this means that any equivocal results are interpreted in favor of the person being tested. Despite the fact that they do millions of tests per year, any documented false positive drug test is carefully investigated by federal agents.

Hospital labs and those that do general clinical work do very poorly by comparison. Drug testing is an evidence-gathering procedure, not a medical test. It is the chain-of- custody and evidentiary procedures that favor the regulated labs, not their medical expertise.

Urine testing is the most common sampling technique and is the backbone of the DOT system. There is a 23-step system for gathering the sample that deals with acceptable techniques for ensuring that the specimen is not tampered with by the donor or the collector. It has been said that only the federal government could require 23 steps to tell someone to pee in a jar. However, this elaborate system ensures that the specimen may be used as legal evidence without being an undue invasion of the individual donor’s privacy. There are also provisions for other types of testing if the individual is medically unable to provide a urine specimen.

Blood testing is the preferred method for medical management of drug problems. Most emergency rooms have access to rapid screening for drugs when treating a known overdose or a coma of unknown etiology. Blood levels are used for setting medication doses in order to keep within therapeutic range. Blood tests are sometimes used as evidence for making medical care decisions: “Is the Alzheimer patient taking his digoxin?”

Unless it is being done at the patient’s request or under a specific court order, blood testing for drugs can be legally problematic. It is more invasive than sampling urine, breath, or hair. Most people resist having blood drawn purely for evidence and most doctors are hesitant to force the issue. If there is a clear legal process, such as an agreement that the county hospital emergency room (ER) will draw blood alcohols on all drivers who are taken into custody, then the physician should follow the procedure. If there is not an established legal procedure, then the doctor is wise to do only those blood tests that are medically necessary.

Evidentiary breath testing is the preferred method of testing for alcohol where it is available. This is not the old Breathalyzer test. It is a new technology that is very accurate. It is just as reliable as blood alcohol testing, but it is noninvasive so legal refusal is more difficult.

The evidentiary breath tests are also DOT regulated. This is the system used for screening truckers, pilots, etc. for illegal alcohol use or intoxication. There are a limited number of brands of machines that are authorized for this program, and the technicians doing the tests must have specific training. Because of these safeguards, the evidentiary breath test is accepted as accurate medical evidence in court.

Hair testing is the new technique for drug screening. It is new and relatively untried. The technical procedures are designed to remove contaminants, such as hair dye and shampoo, and environmental contamination, such as passive smoke, from the hair before it is tested for drugs. The biggest disadvantage of hair testing is that many people find it hard to believe that such contaminants can be removed. The other disadvantage is that many people object to having hair pulled from their bodies, leaving a small bald spot.

The greatest advantage to hair testing is that it detects drug use for the last several months instead of a few hours or days, like urine testing. Some large corporations have gone to hair testing for preemployment screening because it is more effective. A regular drug user may be able to abstain for a few days or a week in order to get a good job. Few drug addicts can stay clean for three to six months just to pass a hair test.

For-cause drug testing is a special issue, regardless of what specimen is being tested. Most screening tests only cover the five federally prohibited drugs: cocaine, marijuana, heroin, amphetamines, and PCP. If the employee is acting intoxicated, it may be necessary to test for legal drugs and alcohol as well. In addition, the physician or nurse may have a duty to evaluate the patient for life- threatening conditions, such as severe head trauma and diabetic ketoacidosis. Most law enforcement personnel assume that the smell of ketones on the breath means alcohol intoxication. A medical professional should realize that diabetes and starvation can cause the same odor and that trauma, seizures, and heart attacks can easily occur when someone is drinking.