Cannabis drug testing is possible using urine, saliva, hair and nail clipping samples. All of these drug tests vary in their windows of detection so recent or chronic cannabis use can be established. In addition, it is possible to identify the ingestion of cannabis as opposed to environmental exposure to the drug.
Cannabis drug testing using urine
Urine drug testing for cannabis involves a donor providing a sample of their urine, which is then analysed for particular substances. A fully-contained screening pot is used to collect the sample, which can be used by both men and women. This method is ideal for on-site testing thanks to it being quick, accurate and providing an immediate result. Urine drug testing is known as a ‘narrow-window’ form of testing as its period of detection is only a few days, although this can depend on the particular substance taken. Drugs including cocaine, MDMA and methamphetamine can be present in urine for roughly 3–5 days, but cannabis can stay in urine for as long as 28 days after chronic use.
AlphaBiolabs has a home drug testing kit that can analyse 14 drugs and their metabolites. The urine drug test kit costs £18.
Cannabis drug testing using oral fluid
Oral fluid drug testing involves analysing a sample of saliva and is another quick way to determine recent cannabis use. The entire test takes just 20–30 minutes and involves placing an absorbent collector inside an individual’s mouth for a few minutes to soak up sufficient saliva. This is another ‘narrow-window’ form of testing and its period of detection is approximately 30–60 minutes after ingestion – up to 48 hours – although, again, this can depend on the particular substance taken.
Cannabis drug testing using hair
Hair drug testing is used to provide a more comprehensive overview of a person’s cannabis use and can determine a history of drug intake for up to 12 months. By segmenting head hair samples into monthly 1 cm sections, a month-by-month profile of cannabis use can be attained. Analysis of small segments can help establish a positive hair test in a narrow timeframe, but unlike saliva and urine tests, hair strand analysis cannot show recent drug history. It can take between 7–10 days for the hair containing the drug to grow above the scalp.
Hair strand analysis also permits the detection of environmental exposure to cannabis. If an individual has been in an environment heavily laden with smoke, for example, each hair sample is chemically washed three times to remove or reduce any drug present prior to analysis. If a donor admits to being surrounded by cannabis smokers, the washing solution could be used to back up any test results.
Cannabis drug testing using nail clippings
Cannabis can be detected in nails because when it is consumed, its metabolites circulate in the bloodstream. These substances pass from the blood vessels below the nail into the keratin fibres as the nail grows.
Approximately 10 mg of nail (either fingernail or toenail) is required in total and they need to be collected as close to the nail bed as possible. Unlike hair drug testing, nail drug testing won’t give a historic segmented pattern of drug use, but it will give an overview of up to 6 months.