| Drug test | |
|---|---|
| Diagnostics | |
To minimize opportunities for tampering, a direct line of sight between the observer and the specimen bottle must be maintained during collection of a urine sample. |
|
| MeSH | D015813 |
A drug test is a technical analysis of a biological specimen – for example urine, hair, blood, sweat, or oral fluid / saliva – to determine the presence or absence of specified parent drugs or their metabolites. Major uses of drug testing are to detect the presence of performance enhancing steroids in sport or for drugs prohibited by laws, such as cannabis, cocaine and heroin.
The following chart from LabCorp gives approximate detection periods for each substance by test type.[1]
The detection windows depend upon multiple factors – drug class,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.
| Substance | Urine | Hair | Blood / Oral Fluid |
|---|---|---|---|
| Alcohol | 6–24 hours[3] Note: Alcohol tests may measure EtG which can stay in urine for up to 80 hours | up to 2 days | 12–24 hours |
| Amphetamines (except methamphetamine) | 1 to 5 days[4] | up to 90 days | 12 hours |
| Methamphetamine | 3 to 5 days[5] | up to 90 days | 1–3 days[5] |
| MDMA (Ecstasy) | 72 hours | up to 90 days | 24 hours |
| Barbiturates (except phenobarbital) | 1 day | up to 90 days | 1 to 2 days |
| Phenobarbital | 2 to 3 weeks[6] | up to 90 days | 4 to 7 days |
| Benzodiazepines | Therapeutic use: up to 7 days. Chronic use (over one year): 4 to 6 weeks | up to 90 days | 6 to 48 hours |
| Cannabis | 2 to 7 days, up to >30 days after heavy use and/or in users with high body fat[7] | up to 90 days[7] | 2–3 days in blood, up to 2 weeks in blood of heavy users[7] However, it depends on whether actual THC or THC metabolites are being tested for, the latter having a much longer detection time than the former. THC (found in marijuana) may only be detectable in saliva/oral fluid for 2–24 hours in most cases. |
| Cocaine | 2 to 5 days with exceptions for certain kidney disorders | up to 90 days | 2 to 5 days |
| Codeine | 2 to 3 days | ||
| Cotinine (a break-down product of nicotine) | 2 to 4 days | up to 90 days | 2 to 4 days |
| Morphine | 2 to 4 days | up to 90 days | 1 – 3 days |
| Heroin | 1 to 4 days[8] | up to 90 days | 1– 2 days |
| LSD | 12 to 24 hours | Undetectable | 2 to 4 days |
| Methadone | 3 days | up to 97 days | 24 hours |
| PCP | 3 to 7 days for single use; up to 30 days in chronic users[9] | up to 90 days | 1 to 3 days[9] |
When an employer requests a drug test from an employee, or a physician requests a drug test from a patient, the employee or patient is typically instructed to go to a collection site. The patient or employee’s urine is collected at a remote location in a specially designed secure cup, sealed with tamper-resistant tape, and sent via express delivery service to a testing laboratory to be screened for drugs (typically SAMHSA 5 panel). The first step at the testing site is to split the urine into two aliquots. One aliquot is first screened for drugs using an analyzer that performs immunoassay as the initial screen. If the urine screen is positive then another aliquot of the sample is used to confirm the findings by gas chromatography – mass spectrometry (GC-MS) methodology. If requested by the physician or employer, certain drugs are screened for individually; these are generally drugs part of a chemical class that are, for one of many reasons, considered more abuse-prone or of concern. For instance, this is, due to their wide recreational use (much more than similar drugs), done to oxycodone and diamorphine, both sedative analgesics. If such a test is not requested specifically, the more general test (in the preceding case, the test for opiates) will detect the drugs, but the employer or patient will not have the benefit of the identity of the drug.
Employment-related test results are relayed to an MRO (Medical Review Office) where a medical physician reviews the results. If the result of the screen is negative, the MRO informs the employer that the employee has no detectable drug in the urine. However, if the test result of the immunoassay and GC-MS are non-negative and show a concentration level of parent drug or metabolite above the established limit, the MRO contacts the employee to determine if there is any legitimate reason – such as a medical treatment or prescription. If the test results are for other reasons, the testing laboratory will instead contact the physician who ordered the test.
On-site instant drug testing is becoming more widely used in those jurisdictions allowing it (such as some states of the USA) as a more cost-efficient method of effectively detecting drug abuse amongst employees, as well as in rehabilitation programs to monitor patient progress. These instant tests can be used for both urine and saliva testing. Although the accuracy of such tests varies with the manufacturer, some kits boast extremely high rates of accuracy, correlating closely with laboratory test results.
Hair analysis to detect drugs of abuse have been used by UK and Canadian courts, and hair testing for alcohol markers is now recognised in both the UK and US judicial systems. There are guidelines for hair testing that have been published by the Society of Hair Testing that specify the markers to be tested for and the cutoff concentrations that need to be tested. There are only a few UKAS ISO17025 accredited laboratories in the UK including Tricho Tech based in Cardiff and Alpha Biolaboratories based in Warrington, UK. Drugs of abuse that can be detected include Cannabis, Cocaine, Amphetamines and drugs new to the UK such as Mephedrone.
The hair follicle test is growing in popularity because it is less invasive than a urine screen, it is harder to falsify or tamper with the specimen, and the detection window is extended to roughly three months. Hair for testing can be collected from anywhere on the body, so the test can be utilized even when someone is bald or shaves their head. Because body hair grows at a different rate than head hair, some people have made the correlation that drug use can be detected in body hair for up to 12 months.
In contrast to other drugs consumed, alcohol is not deposited directly in the hair. For this reason the investigation procedure looks for direct products of ethanol metabolism. The main part of alcohol is oxidized in the human body. This means it is released as water and carbon dioxide. One part of the alcohol reacts with fatty acids to produce esters. The sum of the concentrations of four of these fatty acid ethyl esters (FAEEs: ethyl myristate, ethyl palmitate, ethyl oleate and ethyl stearate) are used as indicators of the alcohol consumption. The amounts found in hair are measured in nanograms (one nanogram equals only one billionth of a gram), however with the benefit of modern technology, it is possible to detect such small amounts. In the detection of ethyl glucuronide, or EtG, testing can detect amounts in picograms (one picogram equals 0.001 nanograms).
However there is one major difference between most drugs and alcohol metabolites in the way in which they enter into the hair: on the one hand like other drugs FAEEs enter into the hair via the keratinocytes, the cells responsible for hair growth. These cells form the hair in the root and then grow through the skin surface taking any substances with them. On the other hand the sebaceous glands produce FAEEs in the scalp and these migrate together with the sebum along the hair shaft (Auwärter et al., 2001, Pragst et al., 2004). So these glands lubricate not only the part of the hair that is just growing at 0.3 mm per day on the skin surface, but also the more mature hair growth, providing it with a protective layer of fat.
FAEEs (nanogram = one billionth of a gram) appear in hair in almost one order of magnitude lower than (the relevant order of magnitude of) EtG (picogram = one trillionth of a gram). It has been technically possible to measure FAEEs since 1993, and the first study reporting the detection of EtG in hair was done by Sachs in 1993.[10]
In practice, most hair which is sent for analysis has been cosmetically treated in some way (bleached, permed etc.). It has been proven that FAEEs are (surprisingly) not significantly affected by such treatments (Hartwig et al., 2003a). FAEE concentrations in hair from other body sites can be interpreted in a similar fashion as scalp hair (Hartwig et al., 2003b).
Hair Alcohol Testing was first commercialised in the UK by Trimega Laboratories.
Saliva / oral fluid-based drug tests can generally detect use during the previous few hours to 1–2 days. THC may only be detectable for less than 12.0 hours in most cases. On site drug tests are allowed per the Department of Labor.[11]
Detection in saliva tests begins almost immediately upon use of the following substances, and lasts for approximately the following times:
NOTE: Saliva tests are poorly sensitive to THC and detection times can vary considerably based on the cutoffs used. In some cases drug use may only be detectable for a few hours.
Adulteration products are readily available on the Internet to avoid oral fluid detection.
Sweat patches are attached to the skin to collect sweat over a long period of time (up to 14 days).[13] 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.[14]
Drug-testing a blood sample measures whether or not a drug or a metabolite is in the body at a particular time. These types of tests are considered to be the most accurate way of telling if a person is intoxicated. Blood drug tests are not used very often because they need specialized equipment and medically trained administers. These factors make it a more costly testing method.
Depending on how much marijuana was consumed, it can usually be detected in blood tests within six hours of consumption. After six hours has passed, the concentration of marijuana in the blood decreases significantly. It generally disappears completely after 30–90 days.
The different types of drug tests are done in similar ways. Before testing the sample, the tamper-evident seal is checked for integrity. If it appears to have been tampered with or damaged, the laboratory rejects the sample and does not test it.
Next, the sample must be made testable. Urine and oral fluid can be used "as is" for some tests, but other tests require the drugs to be extracted from urine. 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 and the sweat collection component is removed and soaked in a solvent to dissolve any drugs present.
Laboratory-based drug testing is done in two steps. The first step is the screening test, which is applied to all samples. The second step, 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, ELISA, and RIA are the most common). A "dipstick" drug testing method which could provide screening test capabilities to field investigators has been developed at the University of Illinois.[15]
After a suspected positive sample is detected during screening, the sample is tested using a confirmation test. Samples that are negative on the screening test are discarded and reported as negative. The confirmation test in most laboratories (and all SAMHSA certified labs) is performed using mass spectrometry, and is precise but expensive. False positive samples from the screening test will almost always 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 laboratories save positive samples for some period of months or years in the event of a disputed result or lawsuit. For workplace drug testing, a positive result is generally not confirmed without a review by a Medical Review Officer who will normally interview the subject of the drug test.
Anabolic steroids are used to enhance performance in sport and as they are prohibited in most high-level competitions drug testing is used extensively in order to enforce this prohibition. This particularly so in individual (rather than team) sports such as Athletics and Cycling.
Can occur at anytime, usually when the instigator has reason to believe that a substance is being abused by the subject.
In the case of life-threatening symptoms, unconsciousness, or bizarre behavior in an emergency situation, screening for common drugs and toxins may help find the cause, called a toxicology test or tox screen to denote the broader area of possible substances than self-administered drugs. The test is usually done within 96 h (4 days) after the estimated time of intoxication. Both a urine sample and a blood sample may be tested.[16] A blood sample is routinely used to detect ethanol/methanol and ASA/paracetamol intoxication. Various panels are used for screening urine samples for common substances, e.g. triage 8 that detects amphetamine, benzodiazepines, cocaine, methadone, opiates, cannabis, barbiturates and tricyclic antidepressants.[17] Results are given in 10–15 min.
Similar screenings may be used in to evaluate the possible use of date rape drugs. This is usually done on a urine sample.[16]
Urine drug test kits are available as on-site tests, or laboratory analysis. Urinalysis is the most common test type and used by federally mandated drug testing programs and is considered the Gold Standard of drug testing. Urine based tests have been upheld in most courts for more than 30 years, however, urinalysis conducted by the Department of Defense has been challenged for reliability of testing the metabolite of cocaine. There are two associated metabolites of cocaine, benzoylecgonine (BZ) and ecgonine methyl ester (EME), the first (BZ)is created by the presence of cocaine in an aqeous solution with a pH greater than 7.0, while the second (EME) results from the actual human metabolic process. The presence of EME confirms actual ingestion of cocaine by a human being, while the presence of BZ is indicative only. BZ without EME is evidence of sample contamination, however, the US Department of Defense has chosen not to test for EME in its urinalysis program.
A disadvantage of saliva based drug testing is that it is not approved by FDA or SAMHSA for use with DOT / Federal Mandated Drug Testing. Oral fluid is not considered a bio-hazard unless there is visible blood; however, it should be treated with care.
Spray (sweat) drug test kits are non-invasive. It is a simple process to collect the required specimen, no bathroom is needed, no laboratory is required for analysis, and the tests themselves are difficult to manipulate and relatively tamper-resistant. The detection window is long and can detect recent drug use within several hours.
There are also some disadvantages to spray or sweat testing. There is not much variety in these drug tests since they are not as popular as urine or saliva drug testing kits, a limited number of drugs that can be detected, prices tend to be higher, and inconclusive results can be produced by variations in sweat production rates in donors. They also have a relatively long specimen collection period and are more vulnerable to contamination than other common forms of testing.[13]
Hair drug testing can detect drug use over a much longer period of time,[18] which is often used for highly safety-critical positions where there is zero tolerance of illegal drug use.[19] Standard hair follicle screen covers a period of 30 to 90 days. The growth of hair is usually at the rate of 0.5 inches per month. The hair sample is cut close to the scalp and 80 to 120 strands of hair are needed for the test. In the absence of hair on the head, body hair can be used as an acceptable substitute.[18] Even if the person being tested has a shaved head, hair can also be taken from almost any other area of the body. This includes facial hair, the underarms, arms, and legs or even pubic hair.
The claim that a hair test cannot be tampered with has been shown to be debatable. One study has shown that THC does not readily deposit inside epithelial cells so it is possible for cosmetic and other forms of adulteration to reduce the amount of testable cannabinoids within a hair sample.[10]
Drug testing is more likely to catch cannabis users, since THC metabolites are fat soluble and have a longer duration in the body than those of other drugs which are widely considered more dangerous such as cocaine and heroin. This can potentially lead would-be cannabis users to switch to harder drugs, most of which generally have significantly shorter detection times and/or are less likely to be tested for.[20] It has also been noted that routine medical tests are subject to errors of the same type that threaten the accuracy of drug tests, but medical tests are neither random nor mandatory, and are usually performed in test panels that give the physician several results to interpret together, with unusual combinations generally resulting in retesting and a search for other corroborating evidence. Drug tests are not parts of such panels, and other evidence is often not available.[21] In 1985, the Centers for Disease Control sent urine samples to 13 unsuspecting laboratories and found that "laboratories are often unable to detect drugs at concentrations called for by their contracts." Wide ranges in accuracy across facilities were noted.[21] One study found that implementation of mandatory drug testing for truckers contributed to a 9–10 percent reduction in truck accident fatalities. The results of federally mandating drug testing were similar to the effects of simply extending to the trucking industry the right to perform drug tests, and it has been argued that the latter approach would have been as effective at lower cost.[22]
A study in 2004 by the Independent Inquiry into Drug Testing at Work found that attempts by employers to force employees to take drug tests could potentially be challenged as a violation of privacy under the Human Rights Act 1998 and Article 8 of the European Convention of Human Rights.[23] However, this does not apply to industries where drug testing is a matter of personal and public safety or security rather than productivity.
Mandatory drug testing entered American life through two separate historical routes. The first was through the common law system, employing precedents philosophically derived from the idiosyncratic rules governing the "king's forest" and the "king's highway". From these arcane precepts are derived the laws which allow legal authorities to detain and test persons under suspicion of driving under the influence of a psychoactive drug.[24]
The second route was more recently constructed and originated from an incident that occurred in the US Navy. After a plane crashed onto the carrier deck of the USS Nimitz in 1981, killing and injuring dozens of personnel, drug testing was instituted immediately. The results revealed a large substance-using cohort within the ranks of enlisted persons and officers. As a result of this single incident, the Secretary of the Navy instituted an intensive drug testing and regulation program. These interventions were then adopted by other branches of the service over a three-year period. From these actions was derived the concept of a "drug-free workplace". In consultation with his drug czar, Dr. Carlton Turner, President Ronald Reagan issued Executive Order 12564. In doing so, he instituted mandatory drug-testing for all safety-sensitive executive-level and civil-service Federal employees. This was challenged in the courts by the National Treasury Employees Union. In 1988, this challenge was considered by the US Supreme Court.[25] A similar challenge resulted in the Court extending the drug-free workplace concept to the private sector.[26] These decisions were then incorporated into the White House Drug Control Strategy directive issued by President George H.W. Bush in 1989.[27] All defendants serving on federal probation or federal supervised release are required to submit to at least three drug tests. Failing a drug test can be construed as possession of a controlled substance, resulting in mandatory revocation and imprisonment.[28]
The federal government sometimes drug tests arrestees who have not yet been convicted. The rationale for such testing is to identify particularly dangerous defendants, the assumption being that drug use is a predictor of other criminal behavior. Research has, indeed, consistently shown that the most frequent, serious offenders are also the heaviest drug users, and studies have shown that persons who tested positive for drugs at arrest were more likely to be rearrested and miss scheduled court appearances than those who did not test positive. One study found that the risk of rearrest in the early weeks after release was about four times higher for drug users than nonusers. There have been inconsistent evaluation results as to whether continued pretrial drug testing has beneficial effects.[29]
Testing positive can lead to bail not being granted, or if bail has already been granted, to bail revocation or other sanctions. Arizona also adopted a law in 1987 authorizing mandatory drug testing of felony arrestees for the purpose of informing the pretrial release decision, and the District of Columbia has had a similar law since the 1970s. It has been argued that one of the problems with such testing is that there is often not enough time between the arrest and the bail decision to confirm positive results using GC/MS technology. It has also been argued that such testing potentially implicates the Fifth Amendment privilege against self-incrimination, the right to due process (including the prohibition against gathering evidence in a manner that shocks the conscience or constitutes outrageous government conduct), and the prohibition against unreasonable searches and seizures contained in the Fourth Amendment.[30]
According to Henricksson, the anti-drug appeals of the Reagan administration "created an environment in which many employers felt compelled to implement drug testing programs because failure to do so might be perceived as condoning drug use. This fear was easily exploited by aggressive marketing and sales forces, who often overstated the value of testing and painted a bleak picture of the consequences of failing to use the drug testing product or service being offered."[31] On March 10, 1986, the Commission on Organized Crime asked all U.S. companies to test employees for drug use. By 1987, nearly 25% of the Fortune 500 companies used drug tests.[32]
According to the Canadian Human Rights Act, random and pre-employment alcohol and drug tests are not allowed in Canada.[33] The one exception to the ban on random drug tests in Canada is alcohol testing including breathalysers in situations where the safety of employees could be at risk if alcohol is consumed at work.[33]
The increasingly common practice of drug testing has led to an increase in the number of drug users looking for ways to beat the tests, and has spawned a number of myths and urban legends as a result. However, this does not stop users from getting creative in their attempts to somehow shorten the detection times and/or mask the contents of their fluid specimens, with varying degrees of success or lack thereof.
This legend is one of the oldest ones in the history of drug testing, and is only partly true. Consumption of vinegar will lower the pH of the blood and urine, and drugs that contain amine groups (such as amphetamines) will be cleared out somewhat faster as their water solubility increases due to protonation. Also, the reduced pH can potentially throw off the pH-sensitive enzymes in a particular type of bioassay (EMIT) often (but not always) used as the initial screening test, even for non-amine-containing drugs such as THC. Also, the effects of urine acidification on detection times (for any substance) are modest at best, often practically insignificant, and drinking vinegar is thus not very reliable as a standalone measure for beating a drug test.[34]
This legend has been around for at least a decade. Niacin, also known as Vitamin B3, is speciously claimed by some to "burn it out" of one's system when taken at high doses (250–500 mg per day). While some Internet (and other) sources often claim that it works wonders, there is no scientific evidence that it has any effect. Very high doses can also cause adverse side effects.[35]
This legend may have been (inadvertently) inspired by Narconon, a Scientology-based drug rehabilitation program that uses exercise, saunas, and high doses of niacin (and other vitamins) to detox. It is also part of L. Ron Hubbard's general Purification Rundown, which Scientology purports to remove pollutants as well as drug residues. However, there are currently no peer-reviewed scientific studies to back these methods up.[36]
Various (mostly internet) sources claim that human urine contains enzymes which, when ingested, can speed the breakdown of THC in the body. While Cytochrome P450 enzymes, which are partially responsible for breaking down THC (and other drugs), are found in trace amounts in urine, there is no scientific evidence to suggest that they can be made biologically available through ingestion.[37] It is possible that this myth is based on some cultures' beliefs that ingested urine contains strong healing and detoxification properties.[38][39]
This legend is technically true but highly misleading. According to a U.S. Army study, the amount of secondhand cannabis smoke needed to cause a false positive result (failure) is quite large indeed, and would require being sealed in an unventilated car or small room filled with marijuana smokers for several hours.[34] Hair testing, however, is a different matter, particularly with passive exposure to crack/cocaine, which can deposit onto hair and be readily incorporated into it.[34] Though for cannabis, typically only metabolites (produced by the body and thus not found in smoke) are tested rather than THC, so failure is unlikely to result from non-extreme passive exposure.[40][41]
While this was true in the past, newer versions of the EMIT bioassay are much less sensitive to ibuprofen (Advil, Motrin, etc.), and this has become relatively uncommon as of 1998, at least in the United States. However, abnormally high doses of ibuprofen can still potentially cause a false positive in some cases. Nonetheless, this no longer works as an alibi for THC since GC/MS can now distinguish between the two.[34]
Poppy seeds do contain trace amounts of morphine, but it would require about 100 poppy seed bagels to reach enough to cause a positive (failed) test result. Poppy seed-filled pastries (such as hamantashen), on the other hand, do in fact contain enough to potentially cause a false positive.[34] A 1996 episode of the highly popular sitcom Seinfeld may have helped perpetuate this urban legend.
An episode of MythBusters tested this legend, and found that as little as three poppy-seed bagels was enough to cause a positive result for the remainder of the day they were eaten (though participants tested clean the following day).[42] The results of this experiment are inconclusive, however, because a test was used with an opiate cutoff level of 300 ng/mL instead of the current SAMHSA recommended cutoff level used in the NIDA 5 test, which was raised from 300 ng/mL to 2,000 ng/mL in 1998 in order to avoid such false positives from poppy seeds.[43] In addition, one thing poppy seeds do not do is serve as an alibi for heroin: a unique metabolite (6-monoacetylmorphine) is produced from heroin use that is never produced from consuming any other substance, let alone poppy seeds. This, however, is only true when diamorphine is being tested for specifically; most tests do not test for heroin, but rather for opiates and opioids as a group. Modern tests can thus readily tease out whether it was heroin or not, should someone try to claim they merely ate poppy seeds.[42]
While this is technically true in some cases, more recent studies have shown that detection times of 30+ days are actually quite exceptional, even for chronic users subjected to tests with lower than normal cutoffs. Under the typical 50 ng/mL cutoff for THC in the United States, an occasional or one-off user would be very unlikely to test positive beyond 3–4 days since the last use, and a chronic user would be unlikely to test positive much beyond 7 days. Using a more sensitive cutoff of 20 ng/mL (less common but still used by some labs), the most likely maximum times are 7 days and 21 days, respectively. .[44] However, one must remember that every individual is different, and detection times can vary due to metabolism or other factors.
There have been many high-profile instances in which individuals or groups have refused to take drug tests. In 2009, a Belgian bodybuilding championship was canceled after doping officials showed up and the competitors fled.[45] Likewise, in 2010, Iranian super heavyweight class weightlifters refused to submit to a drug test authorized by the Iran Weightlifting League.[46] In 2000, an Australian Mining Company South Blackwater Coal Ltd with 400 employees, imposed drug-testing procedures, and the trade unions advised their members to refuse to take the tests, partly because a positive result does not necessarily indicate present impairment; the workers were stood-down by the company without pay for a week.[47] In 2006, Levy County, Florida volunteer librarians resigned en masse rather than take drug tests.[48] In 2003, sixteen members of the Chicago White Sox considered refusing to take a drug test, in hopes of making steroid testing mandatory.[49] In the United States federal criminal system, refusing to take a drug test triggers an automatic revocation of probation or supervised release.[50][51]
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