Drug test

A drug test is a process using some kind of biological matter taken from an individual to determine previous drug use. It's a matter of much controversy; many have argued that it is an invasion of privacy, and the accuracy and effectiveness of some tests are also in question.

General information
Drug tests can be divided into two general groups. The first group is the kind most people are familiar with. This type of testing involves the donor giving a sample of some bodily fluid or hair to an employer, doctor, law enforcement official, or a medical testing center. This is normally a sample of urine, blood, hair, or saliva/ oral fluid. After collection from the donor, the sample is sealed with a tamper-evident seal and sent to a laboratory for analysis. The primary advantages of this type of test are accuracy, legal defensibility, and the ability to customize tests for a particular demographic group. The disadvantages are typically costs associated with the need for collection sites (urine, blood), and the delay in receiving results (up to 4 days.)

The second type of drug test is an on-site (workplace, school, washroom, or at-home) drug test that does not require a laboratory. These types of tests provide the advantages of lower cost and availability of results within minutes. Furthermore, if on-site tests, such as oral fluid-based or saliva tests are used, the problem of "beating the tests" (otherwise known as sample adulteration or substitution) can be virtually eliminated. On-site tests provide qualitative results, and when supplemented with laboratory-based confirmation tests, can be defended in a court of law.

This article will focus primarily on the first type of test, but will refer to the latter when appropriate.

The NIDA 5
Drug testing in the United States basically began in the late 1980's with the testing of certain federal employees and specified DOT regulated occupations. Drug testing guidelines and processes, in these areas exclusively, are established and regulated (by the Substance Abuse and Mental Health Services Administration, formerly under the direction of the National Institute on Drug Abuse or NIDA) require that companies who use professional drivers, specified safety sensitive transportation and/or oil and gas related occupations, and certain federal employers, test them for the presence of certain drugs. These test classes were established decades ago, and include five specific drug groups. They do not account for current drug usage patterns. For example, the tests do not include "synthetic opiates", such as oxycodone, oxymorphone, hydrocodone, hydromorphone, etc., compounds that are highly abused in America:


 * 1) Cannabinoids (marijuana, hashish)
 * 2) Cocaine (cocaine, crack, benzoylecognine)
 * 3) Amphetamines (amphetamines, methamphetamine, speed)
 * 4) Opiates (heroin, opium, codeine, morphine)
 * 5) Phencyclidine (PCP)

While SAMHSA/NIDA guidelines only allow labs to report quantitative results for the "NIDA-5" on their official NIDA tests, many drug testing labs and on-site tests also offer a wider or "more appropriate" set of drug screens which are more reflective of current drug abuse patterns. As noted above, these tests include synthetic pain killers such as Oxycodone, Oxymorphone, Hydrocodone, Hydromorphone, benzodiazepines (Valium, Xanax, Klonopin, Restoril) and barbiturates in other drug panels (a "panel" is a predetermined list of tests to run). The confirmation test (usually GCMS) can tell the difference between methamphetamine and ecstasy, and in the absence of detectable amounts of methamphetamine in the sample, the lab will either report the sample as negative or report it as positive for MDMA. What the lab reports to the client depends upon whether MDMA was included in the panel as something to be tested for.

Gamma-hydroxy-butyrate (GHB) was not routinely tested for in the early 1990s, but due to increasing use, some labs have added it as an optional test. GHB is rare in pre-employment screening, but is commonly checked for in suspected cases of drug overdose, date rape, and post-mortem toxicology tests. Ketamine (Special K) may or may not be tested for, depending upon the preferences of the entity paying for the test, though testing for it is uncommon. In general, the greater the number of drugs tested for, the higher the price of the test, so many employers stick to the NIDA 5 for financial reasons.

Other drugs, such as meperidine (Demerol), fentanyl, propoxyphene, and methadone are not commonly tested for in most pre-employment situations. These drugs are more likely to be included in tests for certain demographic groups (such as healthcare workers, drug rehab patients, etc.)

Hallucinogens other than cannabis and PCP, such as mushrooms (psilocybin), LSD, and peyote (mescaline) are rarely tested for.

Detection periods
The following chart gives approximate detection periods for each substance by test type. The ranges depend on amount and frequency of use, metabolic rate, body mass, age, overall health, and urine pH. For ease of use, the detection times of metabolites have been incorporated into each parent drug. For example, heroin and cocaine can only be detected for a few hours after use, but their metabolites can be detected for several days in urine. In this type of situation, we will report the (longer) detection times of the metabolites. 
 * NOTE 1: Oral fluid or saliva testing results for the most part mimic that of blood. The only exception is THC.  Oral fluid will likely detect THC from ingestion up to a maximum period of 18-24 hours.
 * NOTE 2: Urine can not detect current drug use.  It takes approximately 6-8 hrs. post-consumption for drug to be metabolized and excreted in urine.  Similarly, hair requires two weeks, and sweat, seven days.

Urine drug screen
Also known as urinalysis, this procedure requires that one provide a sample of urine. Either a test card is used on site for immediate results (see "General" section), or the sample is sent away to a lab to undergo gas chromatography/mass spectrometry (also known as GCMS), high performance liquid chromatography or immunoassay analysis. Sample substitution or adulteration have become a significant issue in the United States due to the prevalence of synthetic and/or drug-free urine and a wide range of adulterants on the internet. Some people attempt to defeat a urine test by drinking copious amounts of water, however, a sufficiently diluted sample may be rejected due to its clear color. Samples that are too clear may be flagged and tested for specific gravity. If the sample fails the specific gravity test, the sample is rejected and the dilution is reported to the entity that ordered the test. Some diuretics and herbal extracts, such as goldenseal, are marketed as a quick "detox" from controlled substances, but their efficacy is questionable. Some types of urinalysis can even detect the use of these "detox" products. One of the methods to test for adulterants is to add some amount of an actual drug to a small portion of the sample and then retest that portion. If a masking agent is present in the urine, the resulting drug test will have a negative result despite the fact that a drug was added. This situation is also usually reported to whomever ordered the test.

Hair drug screen
Hair testing is quite accurate and can go back 6 months or longer, showing any controlled substances used in a sort of timeline. As hair grows out, any drugs used are encased in the hair shaft, so the longer the hair, the longer back in the individual's drug history the lab can detect. Most legitimate testing facilities, however, only use hair within about 3-5 cm of the scalp, and discard the rest. This limits the detection history to about 90 days, depending upon the rate of growth of the individual's hair. Some people attempt to circumvent this through shaving their heads. In the absence of the required amount of hair on the scalp, body hair can be used as an acceptable substitute. Additionally, for pre-employment hair testing, the inability to obtain a sample may be grounds for not hiring the individual.

Saliva drug screen / Oral fluid-based drug screen
Saliva / oral fluid-based drug tests can generally detect use during the previous few days. Saliva or oral fluid based drug tests are becoming more prevalent because of their convenience and the fact that they can not be adulterated. Furthermore, on-site oral based tests in particular enable the implementation of random testing programs, proven to be the most effective type of drug screening. Oral fluid based tests are as accurate as urine and can be obtained from quality suppliers in the United States. Testing is usually performed by employers, for either pre-employment, random, post-accident, reasonable suspicion, or return-to-duty testing. Oral fluid based testing most closely mimics results found with blood and is preferable for detecting on-the-job drug use or in post-accident applications in this case because the degree of intoxication can be approximated based on the amount of substance in the blood. The Victorian Police in Australia are also using random saliva-tests to detect drivers under the influence of amphetamines and cannabis. South Australian police were also given the power to drug-test drivers from 2006.

Detection in saliva tests begins immediately upon use:


 * Marijuana and Hashish (THC): 1 hour after ingestion, for up to 14 hours
 * Cocaine (including crack): From time of ingestion for 48 to 72 hours
 * Opiates: From time of ingestion for 48 to 72 hours
 * Methamphetamine and Ecstasy (MDMA, "Crank," "Ice"): From time of ingestion for 48 to 72 hours
 * BZD: From time of ingestion for 48 to 72 hours

Sweat drug screen
Sweat tests are patches attached to the skin to collect sweat over a long period of time (10-14 days). These are almost exclusively used by child protective services, parole departments, and other government institutions concerned with drug use over long periods, when urine testing is not practical. The patches have security features that keep them from being covertly removed and then reapplied without the knowledge of the testing agency. At the end of the test period, the patch is removed by a social worker or parole officer and sent to a lab for analysis. If the person has used any drugs during the period that the patch was in place, they will test positive for that drug. This type of testing has fallen out of favor with government agencies due to documented problems with certain drugs.

Drug testing methodologies
Once the sample arrives at the lab for analysis, the different types of drug tests are tested in very similar ways. Before testing the sample, the tamper-evident seal is checked for integrity. If it appears to have been tampered with or was damaged in transit, the lab rejects the sample and does not test it.

One of the first steps for all drug tests is to make the sample testable. Urine and oral fluid can be used "as is" for some tests, but other tests require the drugs to be extracted from urine beforehand. Strands of hair, patches, and blood must be prepared before testing. Hair is washed in order to eliminate second-hand sources of drugs on the surface of the hair, then the keratin is broken down using enzymes. Blood plasma may need to be separated by centrifuge from blood cells prior to testing. Sweat patches are opened up and the sweat collection component is soaked in a solvent to dissolve any drugs present.

Laboratory-based drug testing is done in a two-tiered fashion using two different types of detection methods. The first is known as the screening test, and this is applied to all samples that go through the lab. The second, known as the confirmation test, is only applied to samples that test positive during the screening test. Screening tests are usually done by immunoassay (EMIT for urine and blood, and ELISA for hair). The screening tests are typically less sensitive and more prone to false positives and false negatives than the confirmation test. Once a suspected positive sample is detected during screening, the sample is flagged and tested using the confirmation test. Samples that are negative on the screening test are discarded and reported as negative. The confirmation test in most labs (and all SAMHSA certified labs) is performed using mass spectrometry, and is extremely precise but also fairly expensive to run. False positive samples from the screening test will be negative on the confirmation test. Samples testing positive during both screening and confirmation tests are reported as positive to the entity that ordered the test. Most labs save positive samples for some period of months or years in the event of a disputed result or lawsuit.

Pre-employment drug testing
This is by far the most common type of drug test used by businesses. It has the advantage of being inexpensive, since only one test per employee needs to be paid for by the company. Furthermore, since most pre-employment drug testing is urine-based and subject to sample adulteration or substitution, the effectiveness of this approach has been questioned by federal legislators.

Random drug testing
This is the most controversial type of drug testing regimen. Some also note that it is also the most effective method to deter drug use. It is usually used by corporations, drug rehab centers, prisons, and more recently, schools. This method may also be used on teens by their parents, or mandated to be performed on teens at school. The point of a random drug test is deterrence, as the threat of detection is much higher vs. other testing methods. Companies use various ways of determining who gets tested, ranging from drawing names out of a hat, to using more defensible methods such as robust random number generators. The goal of this test is to discourage drug use among employees, inmates, or students by not telling anyone who or when they are to be tested in advance. However, critics claim that random testing introduces a presumption of guilt, and is a violation of privacy if the user is not actually intoxicated during working hours. In addition, random testing is more likely to catch cannabis users, since THC metabolites have a longer duration in the body than those of more harmful and addictive drugs.

Post-incident drug testing
This is not a very commonly administered test compared to the other two, but the financial ramifications of not testing employees after an accident (or other incident) on the job makes this test worthwhile for most businesses. The point of this test isn't necessarily to cause the employee to lose his or her job, but rather to protect the company from liability in the event that the individual is under the influence at the time of the accident. If drugs or alcohol are detected in any major quantity, the argument can be made in court that the individual was intoxicated on the job, and for that reason, the company should not be held liable for injuries sustained by the employee. This argument, however, can only reasonably be made if blood or oral fluid / saliva testing is used. Urine, hair, or sweat based testing can only detect past drug use. Depending upon the facts of each case, this may help a company avoid litigation completely or may do nothing to help their case. DUI testing would also fall into this category. Another time this type of test may be used is if an employee shows up for work intoxicated, has alcohol on his or her breath, or appears to be impaired in some other way. The goal of these tests is to protect the entity from litigation, so they are only given on an as needed basis.

United Kingdom
The legal position of drug tests on the UK is not clear. A recent study by the independent Inquiry into Drug Testing at Work found that attempts by employers to force could be challenged as a violation of privacy under the Human Rights Act 1998 and Article 8 of the European Convention of Human Rights. However, this may not extend to industries where drug testing is a matter of safety rather than productivity.