More and more companies are choosing hair tests over urinalysis for drug screening, according to Western Washington University. Hair tests give a drug history that dates back several months. While you may be able to mask the cocaine in your urine, you cannot change the chemical composition of your hair to hide your cocaine use.
The site of the hair sample used in a cocaine test shows differences in trace element and drug concentrations depending on the site. When you go for a cocaine hair test, a lab technician will remove a section of hair about the width of a pencil. The specimen is typically obtained from the back of the scalp. First, the technician will section off a small segment of hair and gently tug to remove any dead hairs. Next, she will cut the hair as close to the scalp as possible. Once removed, the hair is washed before it is tested.
Cocaine is detectable in urine for up to four days, but a cocaine hair test uncovers your history of use for three months. Streetdrugs.org reports that workplace cocaine hair testing found 10 times as many users as urine testing. During the first six months of 2009, three in 1,000 applicants tested positive for cocaine using a urine test. With hair testing, the number of applicants with positive results rose to 32 out of every 1,000.
Cocaine accumulates in the hair, explains the Department of Pediatrics at the Hospital for Sick Children in Toronto, and manifests as metabolites. Metabolites are the remaining by-products after your body processes ingested cocaine. If a cocaine hair test finds these metabolites in your hair, the test result comes up positive. The July 1992 issue of the Journal of Clinical Pharmacology notes that if your hair is exposed to crack smoke, the hair sample may become contaminated.
A study conducted by National Institute on Drug Abuse and published in the Journal of Pharmacology and Experimental Therapeutics in May 2005 demonstrated a cocaine-melanin correlation. Melanin is a pigment that imparts color to hair and skin. Clinical studies involving humans and rats showed “findings of greater cocaine in pigmented than nonpigmented hair.” This finding makes cocaine hair testing controversial, as it has the potential to discriminate against people greater amounts of hair pigmentation.
Newborns suffer the effects of maternal cocaine use, according to the Department of Pediatrics at the Hospital for Sick Children in Toronto. An article in the 1997 issue of Biology of the Neonate explains that components of cocaine cross the placenta to the fetus. A neonatal hair test for cocaine provides information about maternal cocaine use spanning a longer period of time than a urine test can verity. Some babies do not have a sufficient amount of hair to perform a cocaine hair test.