Hair Drug Test Studies Prove the Method is Neither Fool-Proof nor Unbeatable

It has long been thought that a Hair Drug Test, also known as a hair follicle drug test, was the best way for companies and law enforcement agencies to evaluate whether or not an individual has been using drugs. Unlike blood tests, which can only determine whether drug use has occurred recently, hair drug tests have a long detection window. However, in recent times this form of testing has come under some fairly serious scrutiny.

What’s the Problem?

Recent studies have shown that hair follicle testing is not quite as reliable as it was thought to be. Some of these studies researched the correlation between a subject’s THC ingestion and the contents of his or her hair samples. Others addressed the issue of contamination, which can pose a serious challenge when determining the reliability and legitimacy of test results.

Unreliable Data

One study performed in Germany looked at the contents of its subjects hair samples after one month of controlled THC or non-psychoactive THCA use, producing surprising results. Researchers discovered that very few THC metabolites were present in the samples, despite the fact that the subjects had been consuming THC or THCA over a prolonged period of time. As a result of this study, researchers now believe that only the consumption of vast amounts of THC or THCA results in conclusive positive results on hair follicle tests.

Contamination Issues

Contamination of hair samples occurs on a surprisingly frequent basis. For instance, the residue from second-hand smoke can end up contaminating the sample, leading even non-users to test positive for THC. Contamination has also been proven to occur through sweat and sebum contact, proving that the test is far from fool-proof.

What Are the Implications?

The result of recent experiments on the efficacy of hair follicle testing has been to cast doubt on sample reliability, leading in some cases to dismissal or acquittal. Both workplaces and law enforcement agencies have, as a result, been returning to urine sampling and blood testing to determine substance use.

It’s not a safe bet to assume that hair follicle testing will be off the table for good, though. Research is continuing into external contamination, surface versus core metabolites, and other relevant factors. However, far more research into the subject will be needed before hair tests can regain their reputation for accuracy and infallibility.