Drug Testing Info
On one hand drug testing is bound by intricate chemistries, sophisticated technology and, rigid protocol. On the other hand, a quality drug testing program centers on human nature, the mindset of the donor, and the acumen and interpretive skills of the collector and/or test technician.
What follows is intended to offer an examination of various aspects of drug testing. It is intended to: a) offer a review of selected drug test modalities, b) provide a comparison of on-site drug testing versus laboratory based drug testing, c) examine various donor techniques intended to “beat” a drug test, and, d) provide a list of performance characteristics for a quality, on-site drug test product.
Drug Testing is a Four Step Process
Drug Testing is a four step process: collection, screening, confirmation and review.
Regardless of the location of the drug test or the analytical method used to determine the test result, a well run test program should adhere closely to all aspects of the four step process. Poor collection techniques and mistakes in chain-of-custody paperwork are the leading cause of dismissal of evidence in a court. Positive test results generated in the drug screening process are considered to be presumptive until confirmed via an alternative test method, usually an analysis performed on a gas chromatograph/mass spectrometer (“GC/MS”). Prescription drugs, cross reacting compounds, and interfering substances can cause false positives with drug screening tests (both on-site test products and laboratory analyzers). Whereas positive test results obtained in the confirmation step are considered to be conclusive and admissible in a court of law. Finally, before any sanctions are placed on a donor who tests positive, the test results should be reviewed by a medical review officer (“MRO”).
Drug Test Modalities
There are four drug testing methods: urine, saliva/oral fluid, hair follicle, and patch testing.
Urinalysis is the most common of drug testing methods. It has been studied extensively, has undergone challenges in the courts, and is considered to be the gold standard in drug testing. Urine testing is the most affordable of all methods, provides timely results, can analyze up to13 drugs and, its detection window is acceptable. The detection window is the length of time measured in days that a drug is detectable in ones system. Urinalysis can detect drugs from 2-30 days depending on the drug and the degree of use.
There is a great deal of interest in saliva testing as the test method avoids all of the nuances associated with proper urine collection. Oral fluid technology has also improved dramatically in recent years. However, when compared to urinalysis it is considered to be more expensive, offers a limited test menu (up to six drugs) and, it has a relatively small detection window (24 hours or less).
Since hair growth is nourished by the bloodstream, the ingestion of drugs of abuse is revealed by analyzing a small sample of hair. Hair follicle testing measures the drug molecules embedded inside the hair shaft. A hair follicle screen supported by a GC/MS confirmation requires approximately 100 hairs. A standard drug screen of hair 1.5 inches in length has detection window of approximately 90 days. The same sample size can be segmented into 30 day periods. Hair testing results cannot be altered with shampoos, bleaches or other external chemicals. Studies have indicated that laboratory based hair follicle testing is capable of detecting significantly more drug use than urinalysis.
On-Site Drug Testing Versus Laboratory Testing
Drug screening technology - whether performed at point-of-care with rapid technology or conducted in a laboratory on a state of the art chemistry analyzer - is generally considered to be immunoassay technology sometimes referred to as EMIT (Enzyme Multiplying Immunoassay Technique) technology.
Both modalities utilize a cut-off to determine if a test is positive or negative. A cut-off is the level or concentration of a particular drug measured in nanograms per milliliter (ng/ml) where the test is considered to be positive. Example: The cut off for marijuana (THC) is 50 ng/ml. If the concentration of THC in a particular urine sample is 51ng/ml or greater then, the sample is considered to be positive. Cut-offs are national standards and cut-offs are determined by The Substance and Mental Health Services Administration (“SAMHSA”).
The fundamental differences in rapid technology versus a lab based analysis centers on test availability and the types of test results. Both test methods are reasonably accurate. On-site testing provides near immediate test results (5-10 minutes) while it generally takes 18 to 48 hours to obtain drug test results from a laboratory. On-site drug test technology is considered to be qualitative (positive or negative) where a laboratory can provide quantitative test results (“quants”) or an actual measurement of the concentration of the drug present in the donor sample. Positive test results generated via either screening method are said to presumed or suspected positive and should be confirmed by another test method.
Drug testing laboratories will conduct an initial “validity test” to
determine if a sample has been tampered with or if the donor is trying
to mask (adulterate) a positive test result. Adulteration test strips
are also available for use in on-site drug testing programs.
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