Hair testing became popular pretty recently. Back in 1960s and 70s they tested hair for the presence of toxic heavy metals like lead or mercury. The technology was still developing and wasn’t sensitive enough to detect such organic substances as drugs. Later on it was established that pollutants from the blood eventually enter into the hair shaft and stay there until the hair is cut off. This brought an idea of testing the hair structure to determine the presence of drugs – whether or not a person was exposed to certain organic substances in the past. The first hair drug test was performed around 1979: a group of scientists performed a chain of tests of heroine users. Radioimmunoassay showed correlation between the concentrations of morphine along the hair shaft with the time of rug usage. Nowadays, this technology reached new level and is being routinely used to detect a repetitive drug exposure as an alternative to urine and blood drug testing – these tests provide only short-term information on the history of drug use, whereas hair drug testing not only goes back several months, but also can differentiate between single drug exposure and chronic usage. This testing method is currently very popular in forensic science, occupational and traffic medicine, clinical toxicology and in sports. Considered as a fool-proof test, it eliminates all the possibilities of a topical drug application, not only because anything that can be applied to the hair would contain any illicit toxins, but also hair is being tested for the drug metabolites and not the toxins themselves, which would be possible only by consuming the substances internally. Also, the inner structure of the hair that “traps” the metabolites inside leaves no other way of drugs entering the system. Make sure to get a hold of detox shampoo if you are to face a hair drug test in the nearest future.