Drug testing

Various methods of drug testing can be used to determine whether drugs or alcohol are present in a person's system. The main focus of most drug testing is to identify people who misuse alcohol or use drugs inappropriately.

Trends in substance use
An estimated 19.5 million Americans use illegal drugs, with marijuana use widespread and on the rise. Cocaine and heroin abuse remain tremendous problems in many communities. Methamphetamine abuse is a growing concern, partly due to its lower cost and longer-lasting effects. In the United States, 10 percent of men and 3.5 percent of women are considered alcoholics.

Effects of substance abuse in the workplace
People who use alcohol or other drugs heavily and those who become dependent experience the most significant adverse effects of substance use. Even casual use can have negative effects, however. Recently, much attention has been directed toward the effects of substance abuse in the workplace -- especially for occupations that involve public safety.

More than 70 percent of people who use illegal substances are employed. In the United States, alcoholism is responsible for 500 million lost work days every year. Workplace violence, accidents, low productivity, frequent unexplained absences and the rising cost of workers' compensation and disability insurance are often blamed on substance abuse. In total, substance abuse costs an estimated $100 billion or more every year.


Types of drug testing
Blood and urine testing
Simple blood and urine tests can detect many substances, including alcohol and barbiturates. Urine testing is the most common screening test due to the simplicity of collecting urine samples. In fact, urine tests are the standard for government drug-testing programs. Urine testing can be used to detect a variety of drugs, including amphetamines, cocaine, opiates (heroin, morphine, codeine), phencyclidine (PCP), barbiturates, benzodiazepines and marijuana. It's generally the best way to test for commonly abused drugs, such as marijuana, opiates and stimulants.

Sweat testing
Sweat can be used to monitor drug use over an extended period of time. With sweat testing, an adhesive patch on the skin collects sweat for a period of days or weeks. The patch resembles a small adhesive bandage. To prevent possible fraud, the patch can't be reattached if it's removed. Lab analysis of the sweat sample can show amphetamine, opiate and cocaine use. Cocaine -- even when taken in amounts as small as 1 milligram -- may be detectable as soon as one to two hours after use, peaking within 24 hours. Research also shows that sweat contains residue from alcohol, amphetamine, cocaine, heroin, morphine, methadone, methamphetamine and PCP.

Hair follicle testing
After a person ingests a drug, it travels through the bloodstream. Some of the drug is deposited into the hair follicles. Each time a drug is used, it's permanently recorded on the person's hair in chronological order. Hair follicle testing can identify if drug use is increasing, decreasing or remaining the same.

To conduct the test, 60 to 120 strands of hair about 1 ½ inches long are needed. The strands are usually taken from the scalp, but hairfrom any area can be used. After the strands are washed to remove any external contamination, the hair is turned into liquid and chemical screening tests are done. If the screens are positive, a confirmation test is done. Initial results are normally available within 24 to 48 hours, and the confirmation test takes another 48 hours. Since human hair normally grows about half an inch per month, it's easy to tell about how long ago each drug was taken.

Hair follicle testing may be preferred over urine testing because urine samples may be altered. On the down side, hair sample testing is more expensive than urine testing. The legality of this type of testing is also under debate.


Drug test results
Many factors can potentially influence drug test results -- especially urine tests -- including:
the person's age
the person's organ function (The concentration of urine can vary, which may impact the results of certain tests.)
any medications the person may be taking
how certain drugs are metabolized
natural substances in food
fraud (The person may attempt to substitute urine or alter urine samples -- possibly by drinking lots of water, taking diuretics or swallowing interfering substances.)
Results can also be influenced by the timing of the test. With urine tests, for example, "first morning urine" often reveals the most evidence of drug use. Cocaine, opiates, amphetamines and barbiturates can be detected through urine tests for about two to four days after use. This time frame may vary depending on the amount and frequency of use, the accumulation of drug within fat and other body tissues, as well as the use of a longer-acting vs. shorter-acting drug. For occasional users, marijuana may be detected for four to six days after use. After repeated use, marijuana may be detected for 20 to 50 days.

Because false-positive results are possible, a more specific test known as gas chromatography-mass spectrometry testing is often used to confirm positive results. Since the tests don't differentiate between casual users and people who are addicted or impaired by drug use, a doctor or substance abuse professional may be consulted to interpret test results, explore possible reasons other than abuse for positive test results, or evaluate the person and give treatment recommendations.


Recommendations
The American Medical Association (AMA) supports the appropriate use of drug testing, rehabilitation and treatment. Drug testing is an important part of many pre-employment exams, especially for people whose occupations may affect the health and safety of others. For current employees, the AMA and other health organizations recommend urine testing if there's reasonable suspicion of substance abuse. Random urine sampling can help promote a more drug-free workplace, but routine drug screening of all employees isn't encouraged.
Federal regulations clarify the details of certain drug and alcohol testing programs, such as documentation of testing steps as required by the U.S. Department of Transportation and other state and federal programs. As research continues, the drug testing process will continue to evolve.