Drug testing detects the presence of drugs and drug metabolites in the body using drug test cutoff levels to determine whether or not a person consumed drugs. Drug testing may be used to detect illicit drugs (e.g. cannabis, cocaine, ecstasy, meth), as well as over the counter and prescription medication (e.g. morphine) not permitted while driving, or in specific workplaces.
For workplace and roadside drug testing, the standard procedure involves an initial screen and if the results are positive, a confirmation test. Depending on the resources available and the time constraints, screening can be performed in the laboratory or on-site using rapid tests. Hence arise the questions: when should employers, law enforcement agencies use in-lab drug testing and when should they use an instant drug test? What differences are there between initial and confirmatory testing? Read on to find the answers to commonly asked questions regarding drug testing.
The standard drug testing process involves an initial screen for drugs in body fluids (such as oral fluid, urine), followed by a confirmatory test in case of positive results.
Rapid drug tests are also known as instant tests because you get your results immediately on-site. With the rapid drug test, the results are negative or positive. A positive result for any of the tested drugs is considered presumptive as it only indicates the possible presence of the drug or metabolites in the specimen, but does not quantify the concentration of drugs. Presumptive positive specimens are sent to a laboratory for further testing (confirmation testing) and take an additional 2-3 days.
Rapid drug tests are lateral flow tests based on the immunoassay method. The immunoassay method is based on the interaction between the target and its corresponding antibody. More details on the lateral flow technology can be found in the upcoming Synens white paper.
In most cases, the results from rapid drug tests are being read by an officer or a safety manager at the point of collection. Visual interpretation is subjective and can lead to human error interpretation. To prevent misinterpretation, Synens uses electronic analyzers for more reliable on-site results analysis, the D1 handheld analyzer.
When a sample (e.g. oral fluid, urine) is sent to the laboratory, it undergoes an initial screening process to make a distinction between positive and negative samples. Laboratories ensure that the results provided are accurate and reliable. If the initial screening reveals the presence of a drug or a metabolite, the sample is examined in more detail to identify the drug and its concentration (confirmation testing).
It seems obvious that the main difference between a laboratory drug test and a rapid drug test is time-related, but another difference regards money considerations. The rapid drug test is quick and therefore gives much faster results, while laboratory screening tests might take more time due to more detailed-oriented screening methods and other previous engagements. Lateral flow tests are also less expensive than laboratory screening, as the latter has additional costs added to the total price of analysis. Thus, lateral flow tests, such as the OM90 drug test kits, are both cost and time-effective alternatives for drug screening.
A confirmatory drug test is a second test conducted after one or multiple drugs have been detected during an initial drug screening test. The presence of the drugs indicated by a positive screening result must be confirmed in a laboratory. Confirmatory testing requires collecting a second sample that is sent to the laboratory in the pre-defined time period – generally the day after -. The laboratory is using chromatographic methods in combination with mass spectrometry such as Gas Chromatography-Mass Spectrometry (GC/MS) or Liquid chromatography-tandem MS (LC-MS-MS) to confirm the presence of the drug in the collected sample and determine its concentration.
Thus, using GC-MS or LC-MS/MS, it is possible to determine if the driver/employee has consumed illegal substances, what substances and in what concentration were they present in the analysed sample. The methods are highly accurate and sensible, making the results, under professional expertise, eligible in court, if necessary. The toxicologist expert is the one responsible for interpreting analytical results for the organization requesting the drug testing service or the organization's designated Medical Review Officer.
Nowadays, all laboratory screening and confirmation assays must be calibrated against appropriate standards and by following laboratory protocols. Laboratories must respond to common quality assurance and quality control criteria that are capable of being accredited by an external body.
Drug screening tests use cut-off levels to determine whether a specimen tests positive or negative for the use of a specific or multiple drugs.
In drug testing, the cut-off level is the concentration, above which an individual tests positive for taking drugs. It is measured in nanograms per millilitre (ng/ml). A drug test cut-off level is a threshold. If the concentration of a drug is above the cutoff level, it is a positive result. If it is below, it is negative. Note that a negative result does not mean “no drugs”. It merely means that if any drugs are present, they are below the cut-off level. In other words, the drug/metabolite can be present at a concentration below the defined cut-off level.
Refer to Synens Window of Detection for Drugs Whitepaper for further details on cutoff levels
Most laboratories and many point-of-care tests (POCTs) use the cut-off concentrations established by the government, mandatory guidelines or program requirements for non-regulated employers. The proposed cut-offs are the best approach and compromise taking into account the scientific information regarding the pharmacokinetics and pharmacodynamics of the drugs, the cross-reactivity with other compounds, the technologies limitations and the number of false-positive. Synens thus customizes its drug testing panels to its client’s requirements to be more sensitive.
There are two cut-off levels panel. One cut-off level panel is for screening and one is for confirmation. Screening and confirmation testing are performed using different methods, hence they have different sensitivity and specificity. Confirmation drug testing is more sensitive. The cut-offs levels of the confirmation tests are lower than the point-of-care drug tests in order to make sure that the compound is correctly identified.
Screening Cutoff Level (OM90)
Recommended Confirmation cutoff levels
Recommended Confirmation cutoff levels
An on-site drug test only provides a preliminary screening result (initial testing). In other words, any positive result from an on-site drug test is considered presumptive only. In case of presumably positive results, a more specific alternative methodology must be used in a laboratory in order to obtain a confirmed analytical result.
Many employers test their employees for drug use, especially in safety-sensitive industries like construction and manufacturing, in order to create and maintain a safe workplace. As an employer or human resources representative, you have the right to require workers in safety positions to come to work sober and unimpaired as outlined in your Workplace Drug & Alcohol Policy. In workplace drug testing, employers generally choose one or more of the following times to drug test:
Screening can help protect employees from injury and improve productivity. Companies with employees in safety-sensitive positions may wish to carry out random screening after the employees have been hired. Some employers like to conduct random screening for workers who drive, operate heavy equipment or work on hazardous construction sites.
The technical term for roadside drug testing is “preliminary test”. Driving while under the influence of any drug is forbidden and carries serious penalties and a mandatory period of disqualification from driving. Roadside or preliminary testing enables the police and customs officers to rapidly and efficiently establish whether the driver was driving whilst under the influence of drugs. The police generally undertake preliminary testing by using oral fluid lateral flow tests. Law enforcement agencies can also carry out a urine test, but this is less commonly used. Only a doctor or trained technician can undertake the urine drug screen.
The results for onsite checks by law enforcement agencies need to be in as quickly as possible. Hence, law enforcement agencies (police officers, customs) use lateral flow tests (e.g. OM90 drug test kit) to detect illicit drugs or prescription drugs. Some prescription medications can indeed impact driving.
Roadside drug testing procedure is specific to the state/territory screening is performed in. Generally, the procedure for roadside testing for meeting or exceeding the prescribed concentration of drugs is as follows:
Testing is mandatory in the case of a road traffic accident involving death or injury. A police officer can require a driver to take a preliminary drug test if the officer reasonably suspects that one of the following applies:
Did you know that the detection times are longer in urine than oral fluid? Police officers perform oral fluid drug testing, as it detects recent drug use. In workplace testing, the purpose of rapid drug tests is to prevent employees from undertaking safety-sensitive tasks while impaired. An oral fluid test is then more suitable as the recent use of drugs may imply effects. The choice of the matrix or sample depends on the desired detection times.
To better understand detection time and how to choose the right drug test, Synens dedicated a white paper on the subject of detection times that help you choose the right drug test. Synens details the drug detection times and the factors that affect the window of detection for drugs in urine and oral fluid. The window of detection is the interval of time between first positive detection and last positive detection.
The first real drug screening process was initiated by the U.S. Department of Defence (DOD) during the early 1970s3 to deal with the problems of marijuana and heroin use by soldiers in Vietnam. Most of the urine samples were tested by the Addiction Research Foundation, Toronto, Canada, under the supervision of Dr B. M. Kapur.
In Southeast Asia, cannabis and opium poppies were common agricultural crops. Heroin was strong, easy to get and taken by smoking, rather than by needle, and inexpensive. The combination of war and substance availability turn a number of American soldiers in Vietnam onto heroin and marijuana.
In June 1971, the U.S. military announced that they would begin urinalysis of all military service members returning from Vietnam. American soldiers in Vietnam would not be permitted to board a plane home until they passed a urine drug test. If they failed the drug test, the soldiers would be forced to stay in Vietnam until they pass the urine drug test.
The urine samples were analysed in laboratories using various methods such as Radioimmunoassay or Gas Chromatography-Mass Spectrometry (GC/MS). The use of either method of immunoassays (e.g. radioimmunoassay) and Gas Chromatography was widely and generally accepted for urine drug testing. At the time, and up to 1985, there was no consistent program for the use of GC/MS in the Quality Control (QC) of Gas Chromatography (GC) confirmations between laboratories. Most of the GC/MS effort had been on THC, with no effort on other drugs5. In the 1970s, there was no consistent quality control protocol or program followed in any Drug Testing Laboratory to support the GC methods for drugs except cannabis.
(1). EWDTS Guidelines. “European Guidelines for Workplace Drug Testing in Oral Fluid”.
(2). SAMHSA Guidelines and Resources. “The Oral Fluid Mandatory Guidelines”.
(3) Spiegel, Alix. ‘What Vietnam Taught Us About Breaking Bad Habits’. NPR, 2 January 2012.
(4). Robins, LN. “The Vietnam Drug User Returns”. Special Action Office for Drug Abuse Prevention, Series A, Number 2, Appendix B, Pages 102, May 1974.
(5). Review of urinalysis drug testing program. Report by a panel of army and civilian experts in toxicology and drug testing legal issues. 12 December 1983.
https://prhome.defense.gov/Portals/52/Documents/RFM/Readiness/DDRP/docs/28 Einsel Commission Report.pdf