Below is an excerpt from our new ebook, “Are You Ready for Hair Follicle Drug Testing?”
AUGUST 4, 2016 – As more trucking companies look to reduce drug use among their drivers, hair follicle testing is becoming an increasingly popular way of screening candidates. The reason, is that unlike urinalysis, which shows only two to three days of drug use, hair testing typically goes back a full 90 days. This provides a clearer picture of a driver’s drug history and can allow companies to make more informed decisions about who they allow behind the wheel.
As the body breaks down drugs in the bloodstream, it produces something called metabolites. Metabolites are essentially a genetic record of the person’s drug use, providing clear evidence of the drugs they’ve ingested. These metabolites are absorbed from the blood into the hair follicles where it is passed into the growing hair strands. They remain in the hair until it’s cut, providing detectable evidence of drug use long after the substances have left the body.
To perform a standard hair follicle drug test, the hair is cut as close to the roots as possible – typically from the back of the head in a place where it’s not readily noticeable. Approximately 90-120 strands are needed for the test.
If the person doesn’t have enough hair on their head, or the hair isn’t long enough, the hair can be cut from elsewhere on the body. In general, hair can be taken from anywhere as long as it’s at least an inch-and-a-half long. Common locations include the chest, armpit and leg.
Even if the hair is longer than needed, typically only the first inch and a half from the root is tested. Although each person’s hair grows at a different rate, this provides about a 90-day history of past drug use. Because body hair grows at a much slower rate, samples taken from other parts of the body may show up to 12 months of drug use.
Once the hair is collected and cut to the appropriate length, it will be washed thoroughly to remove any external contaminates. Once clean, the hair can be tested for drug exposure and metabolites.
There is some concern that exposure to second-hand marijuana smoke, for example, will lead to a positive test result – even if the individual didn’t smoke the drug themselves. However, because hair tests look for the presence of metabolites, in addition to exposure, a positive test result couldn’t be achieved through second-hand smoke alone. These metabolites are only produced when the drugs are present in the person’s bloodstream.
To read more about hair follicle drug testing, and its implications for the transportation industry, download the full ebook here.