Why did Marijuana (THC) show up negative?
In some cases, when the donor has used marijuana, a hair drug test, including HairConfirm, may be unable to detect the THC metabolite due to the fact that the metabolite was unable to bind with the hair shaft. This can be caused by the type/quality of the marijuana smoked/ingested, or by what it has been mixed with, e.g. tobacco. As a result, the result for marijuana may be negative. This is only the case with THC and not with the other illicit drugs (COC, Heroin..etc). In most cases with adults it takes smoking 5-6 full joints in order for enough of the drug to “stick” to the hair to show a positive- this is an average number. If the amount consumed by the individual was less than that it might not show up in a drug test.
