Choosing the right testing method for drug and alcohol use is essential to achieve a fair outcome in a courtroom, workplace, or any other situation where parental custody, child safety or future employment might be at stake.
Today, hair, blood, urine and oral fluid (saliva) tests are the most common, trusted methods for analysis of drug and alcohol use. Understanding the advantages, disadvantages and relevance of each method requires awareness of the accuracy, window of detection and collection method for each.
To help you choose the correct test for your situation, we’ve compared the advantages and disadvantages of all four types of test below.
Useful for cases where an individual is accused of long-term substance use, hair tests show drug and alcohol use over months with absolute accuracy. A sample of hair is cut from the scalp, or elsewhere if the donor is bald – preferably by a trained collector. Hair tests are being increasingly used before candidates begin employment.
Detects: Alcohol consumed 3 - 6 months ago; drugs used 7 days – 12 months ago
Tests for: All drugs. Some of the most common include:
- Cocaine group: Benzoylecgonine, Cocaine, Cocaethylene, Norcocaine
- Opiates group: 6-Acetylmorphine, Codeine, Dihydrocodeine, Morphine, Heroin
- Methadone group: Methadone, EDDP
- Tramadol group: Tramadol, Desmethyl Tramadol
- Amphetamine group: Amphetamine
- Benzodiazepines group: Diazepam, Nordiazepam, Lorazepam, Nitrazepam, Oxazepam, Temazepam
- Cannabinoids group: THC, Cannabinol, Cannabidiol, THC-Carboxylic Acid (THC-COOH)
- Mephedrone group: Mephedrone, Methamphetamine group: Methamphetamine, MDMA, MDA, MDEA, MBDB
- Ketamine group: Ketamine, Norketamine
- Alcohol markers: ETG, FAEE (Ethyl-Myristate, Ethyl-Oleate, Ethyl-Stearate, Ethyl-Palmitate)
Accuracy: 100% accurate, providing the context for the collection of the sample is known and the chain of custody for the sample is secure
Advantages: Able to detect usage over long periods, difficult to subvert test; non-invasive collection method
Disadvantages: Cannot indicate accurately amount of drugs used or test acute intake.
Oral fluid (saliva) testing
Commonly used in pre-employment and workplace testing, including to confirm results of other tests. Sampling is simple and does not require trained collector.
Detects: Drug and alcohol use over past 0 – 2 days
Tests for: All Drugs
Accuracy: Very accurate; offers the first sign of drugs after use. Most drugs are detectable for up to 6 hours, and some will remain for up to one day.
Advantages: Simple collection method; low risk of tampering
Disadvantages: Low volume samples make retesting difficult; donor anxiety can make collection difficult
Best used when an individual has a history of substance use. Tests must be taken regularly over weeks, and be supervised to prevent donor tampering with (diluting) their sample. Commonly used for pre-employment and workplace testing.
Detects: Drug and alcohol use over past 0.5 – 5 days
Tests for: All drugs
Accuracy: Highly accurate, but restricted time window makes it possible to escape detection by delaying test after consumption. Methods for avoiding detection are well publicised.
Advantages: Able to assess acute drug intake; cost-effective test method and large specimen volume allows for retesting. On-site ‘dipstick’ testing available for most common drugs.
Disadvantages: Samples can be tampered with by diluting water; medical condition or shy bladder can prevent donor producing sample
A well-respected method requiring special medical equipment and a trained collector. Detects substances currently in donor’s system.
Detects: Immediate drug and alcohol use
Tests for: Alcohol and all drug types
Accuracy: Liver Function Tests (LFTs) accurately confirm excessive alcohol consumption by indicating liver damage. Carbohydrate Deficient Transferrin (CDT) indicates excessive alcohol use but can generate false positives. Method is used to confirm other bodily indicators of alcohol use.
Advantages: Established, effective method for assessing substance use in-the-moment
Disadvantages: Invasive collection method, requiring special equipment and a trained phlebotomist
In addition to choosing the most appropriate test method, selecting the right laboratory to perform your substance test is essential. Without doing so, the accuracy of any test result can be put into question – invalidating the test as a form of evidence.
More than two decades ago, the team at Cansford Laboratories pioneered hair testing in the UK. Today we lead our sector, delivering accurate results in under 3 days – exceeding industry standards for both speed and reliability.
To find out more about hair testing – including the process, costs and test accuracy – download our free 20-page ebook, ‘The complete guide to hair testing for drug & alcohol’.
Image from Pixabay, CC0 public domain