What is drug testing?

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Drug testing is the screening of human body fluids, primarily blood, urine, and saliva but also hair, to identify the presence of illicit drugs, including marijuana, phencyclidine, methamphetamine, and cocaine. Drug screens also detect the presence of frequently abused prescription drugs, such as amphetamines or opiates. Additional screens for alcohol, hydrocodone, barbiturates, benzodiazepines, and other drugs may be used by federal agencies, and federal contractors use urine screens only, based on the provisions of the Drug-Free Workplace Act of 1988.
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Drug Screening Basics

Many organizations testing for drugs use a drug panel that tests urine for multiple drugs. Drug screens often test for the metabolites of substances, or the chemical results that are found within the body after the drug is processed. A positive urine test is followed by a confirming test for the specific drug. For example, the metabolite for marijuana is tetrahydrocannibinol (THC). If the first test is positive for THC, then a confirming test for delta-9-tetrahydrocannabinol-9-carboxylic acid is performed, confirming (or denying) marijuana use. The opiate screening will test for opiate metabolites, and a confirming test will test specifically for the opiate drugs codeine or morphine.

Government and private employers are major users of drug testing methods, and many private firms have created their own drug testing programs. The American Management Association estimated in 2004 that nearly two-thirds (62 percent) of employers in the United States use drug testing.

Drug screens are used for six primary reasons. The first reason is to prescreen potential job candidates for drug use. The second reason is to randomly test workers as a deterrent to drug use on the job and to identify safety hazards in persons in high-risk occupations. Third, tests may be performed if there is a reasonable suspicion that a specific person is abusing drugs. Fourth, tests may be ordered subsequent to an employee accident, and fifth, upon the return to work of an employee involved in an earlier accident. Sixth, employers will use a follow-up test to recheck an employee following a positive drug screen. Employers will often use toxicology screens to test an employee before a promotion or to test an employee during that employee’s annual physical examination.

One key reason for the implementation of drug testing in the twentieth century was to deter workplace drug use, and screening appears to be working. According to the US Substance Abuse and Mental Health Services Administration (SAMHSA), the number of positive drug tests at worksites around the United States plummeted from 13.6 percent in 1998 to 3.6 percent in 2009. However, according to Quest Diagnostics and the analysis of over ten million workplace drug test results, the positivity rate for urine drug tests (6.6 million) had increased for the first time in years by 2013 and had increased once again to 4.7 percent in 2014.

Any positive test for drugs is often followed by a more sophisticated test, one that uses gas chromatography/mass spectrometry (GS/MS) to test for specific substances. If this test is positive too, it will be given to a physician knowledgeable about drug abuse for further review.

Law Enforcement Drug Screening

Law enforcement officials test for drugs among persons involved in automobile and other vehicle accidents to determine if alcohol or drugs may have been a factor in causing the accident. Law enforcement often uses drug screens to test persons who have been arrested to determine if that person was under the influence of drugs at the time the alleged crime was committed. Incarcerated persons are subject to drug screening, as are those who are on probation or parole. A positive drug screen for a person on probation or parole often means he or she will be sent back to jail or prison, because a positive drug screen is usually a violation of the terms of probation or parole.

Drug courts throughout the United States manage the cases of persons convicted of drug offenses, and drug testing is an integral part of the program. It is estimated that more than one thousand courts have drug courts to manage drug offenders.

Drug testing also may be sought by law enforcement because some drugs are known to escalate the risk of violence. As a result, a person in custody for committing a violent act may be tested for recent drug use, especially for the use of a drug, such as methamphetamine or cocaine, that is linked to violent behavior. According to research by SAMHSA (2002–2004), among adolescents age twelve to seventeen years, all of whom had engaged in violent behavior in the past year, 69.3 percent had abused methamphetamine, 61.8 percent had abused cocaine, and 61.4 percent had abused hallucinogens in the past year. Marijuana was found to be used by nearly one-half (49.7 percent) of the adolescents deemed violent.

Other Reasons for Drug Testing

Competitive athletes are barred from using drugs such as anabolic steroids, which are known to increase muscle mass and endurance but which also have many serious health effects. Also, athletic organizations use drug screening to ensure that high school, college, and professional athletes remain drug free because drugs affect athletic performance and can provide an unfair advantage in competition.

In 2015, it was announced that the Electronic Sports League, one of the largest leagues in competitive video gaming, would be forming guidelines to institute a testing program for players involved in these e-sports. This decision came after it was revealed that some professional gamers had taken drugs such as Adderall to sharpen their focus during competitive gaming tournaments.

A 2002 ruling by the US Supreme Court (Pottawatomie County v. Earls ) allows schools to test students who are not athletes, through random drug tests. Schools that adopt such programs believe that random testing can deter students from abusing drugs and also believe that testing allows for the identification of students with drug problems, who would benefit from counseling.

Pain management doctors may test their patients to ensure they are taking only the drugs that are prescribed to them and not taking any additional drugs of abuse. Some people who are prescribed drugs such as opiates, amphetamines, and benzodiazepines divert (mostly sell) their drugs to others. In this case, a negative test for the prescribed drug is problematic, indicating that the person is not taking the prescribed drug. Pain management doctors also want their patients to take only scheduled drugs that are prescribed; doctors are alerted if the test reveals the presence of nonprescribed drugs of abuse. Some pain management doctors require patients to sign a contract that they are willing to be tested randomly for drugs. If the patient refuses to sign the contract, the doctor will not provide treatment.

Persons admitted to emergency rooms with an altered mental state are often tested for drugs to help medical professionals determine whether the behavior is likely caused by drug abuse or by mental illness. One complicating factor is that some mentally ill persons also abuse drugs. It should be noted, however, that few mentally ill persons are violent. However, research has indicated that the abuse of alcohol and drugs escalates the risk for violence among people with mental illness.

Substance abuse treatment facilities may require drug screening to ensure that patients in the facility are not using drugs that they have acquired illicitly, that is, drugs brought to the facility by visitors or others. Child protection workers may request drug screening to verify that former addicts who had abused or neglected their children in the past are no longer using drugs of abuse. Sometimes young children are tested for drugs, particularly if it is known that a parent has abused drugs in the past. Investigators may test the child’s hair or urine for traces of drug use. If drugs are found in the body fluids or hair of a child, the child may be removed from his or her home. Additionally, small children sometimes ingest drugs carelessly left out by drug abusers; these children are at risk of cardiovascular or neurological symptoms, even death.

Pros and Cons of Testing Methods

Although urine is the most common fluid screened, organizations do seek other means for screening for drugs; each screening method has advantages and disadvantages. For example, because hair grows about one-half inch per month, testing of the hair can determine the presence of drugs from several months prior to the test. In contrast, screens of the urine can detect drugs used within hours or days only, with some exceptions. As a result, if recent abuse of drugs is sought, then tests of the urine or blood are preferable; if information on long-term drug abuse detection is sought, then hair testing for drugs may be preferable.

Another factor in determining what test to use is the speed at which the test results are needed. Urine and blood test results usually can be obtained rapidly. In contrast, hair must be sent to a specialized laboratory for analysis. Oral fluid testing, often referred to as saliva testing, can be done on-site, although this test is not as commonly used as urine or blood testing.

The reliability of a given test is another factor. For example, hair testing can be affected by the use of hair bleaches and dyes by the person providing a sample. Up to 60 percent of drugs may be removed through such processes. The drugs least affected by the use of cosmetic substances for the hair include cannabis (marijuana and hashish) and opiates. Urine testing and blood testing are highly reliable, although false positives can occur with urine testing. In addition, often there is no first-hand observation of the collection of urine for testing, as is with testing of the blood, hair, or oral fluids. As a result, some people deliberately attempt to alter urine test results by, for example, submitting the urine of another (likely drug-free) person.

The invasiveness of a given test is sometimes a consideration in choosing the type of test. Saliva testing is considered noninvasive because it requires that the person simply spit multiple times into a special container. Hair testing is noninvasive because it requires cutting only a few strands of hair close to the scalp. Urine testing is not considered invasive but it can be embarrassing if the examiner listens outside the door. Conversely, blood testing is the most invasive form of blood testing because it requires the penetration of the skin with a needle to collect the blood.

Drug Positives and False Positives

In most cases, a person who tests positive for a drug most likely used the drug. Positive drug screens may lead to job termination or to not being hired for a job. Some people may test positive for a drug, especially with a urine screen, even if they have not used the drug in question.

It also is true that a person will test positive for a drug that they have been prescribed. A person being treated for attention-deficit hyperactivity disorder, for example, will test positive for amphetamine use. While tests can determine the presence of, in this case, amphetamine, tests cannot determine if the person is using the drug lawfully.

Some medications may cause a false positive on a urine screen. For example, nonsteroidal anti-inflammatory drugs (NSAIDs) may give a false positive for the use of marijuana. NSAIDs may also give a false positive urine result for barbiturates, a type of controlled drug that is included in some drug screens. The use of a Vicks inhaler may give a false positive result in the urine for an amphetamine. The use of sertraline (Zoloft), a commonly used antidepressant, may give a false positive for benzodiazepine. Other antidepressants, such as bupropion, desipramine, and trazadone, may give a false positive result for amphetamine use.


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