The findings made headlines when they came out recently—more Americans failing workplace drug checks than at any time in the last decade.
Quest Diagnostics’s report in September that workforce drug use had reached a 10-year high came from an analysis of more than 10.5 million drug tests that the company conducted for employers in 2015. Most of those tests used urine or saliva. But 200,000 tests were performed on hair, and those tests showed the greatest increase, the report found.
But those findings might not be what they appear. Hair testing for drug use, available for decades, is a developing science. The tests are offered by a number of private testing companies, and approved by the FDA, but the federal governmentdoesn’t currently recognize hair as a reliable sample for federally regulated programs. And studies over the years have indicated that hair can absorb drugs in the environment and may show higher concentrations in dark-colored hair, leading to possible racial bias.
However there are signs that the tests are coming into the mainstream. The Department of Health and Human Services is in the process of evaluating hair testing (alongside saliva testing) as a potential addition to the federal employee screening process. It expects to release guidance by the end of this year. That could mean that many federal agencies, military members, organizations receiving federal grants, and large government contractors could be adopting hair testing in the future.
Meanwhile, a case awaiting a ruling at the Federal Court of Appeals for the First Circuit rests on whether hair testing is racially discriminatory, a question that is sure to come up in HHS’s ongoing deliberations about the technique.
The hairy details
Hair testing has been widely available since the 1980s. Testing labs take about 120 strands of straight hair, or a cotton-ball-sized sample of curly hair, to do the analysis. After washing, the hair is dissolved in solvents. The resulting liquid is analyzed using gas chromatography and mass spectrometry to identify any drug metabolites that may be present.
The premise is that as new hair cells form in the hair follicle, they absorb molecules of substances circulating in the blood. Those molecules get embedded into the hair cells, creating a permanent, chemical record that stays in the hair as it grows out of the skin.
Drug molecules can appear in the follicle within minutes of ingestion, and remain detectable for up to 90 days in most cases. Testing companies thus market the test to employers as offering more information than urine tests.
“Employers are interested in hair testing as a kind of lifestyle test,” said Barry Sample, a pharmacologist and head of science and technology for Quest. More employers are using the test, Sample said, because of the opioid epidemic.
But the hair test doesn’t do these tasks as well as it needs to, according to two lawsuits on behalf of Boston police officers fired between 2001 and 2006 after drug testing on their hair turned up positive for cocaine.
The plaintiffs denied that they used cocaine in state and federal lawsuits filed in 2012. In the state case, which involves six officers, the plaintiffs argued that the test is not accurate enough to alone determine drug use. Last month, the Massachusetts Appeals Court ruled for the officers’ reinstatement, upholding an earlier decision that “the risk of a false positive test was great enough to require additional evidence to terminate an officer.”
The federal lawsuit, on the other hand, contends that hair testing is subject to possible racial bias. The case was heard by the Federal Court of Appeals for the First Circuit last month and is now awaiting a ruling.
“The hair test cannot distinguish between ingested drugs and environmental exposure,” said Ivan Espinoza-Madrigal, executive director of the Lawyers’ Committee for Civil Rights and Economic Justice, which is representing the officers in the federal lawsuit.
Like cigarettes, smoked drugs such as marijuana, crystal meth, and crack cocaine can contaminate the air—and hair—around them, according to a report from the Substance Abuse and Mental Health Services Administration (SAMHSA). The report also points out that close contact with a drug user could also contaminate hair.
Labs are supposed to take steps to prevent that kind of contamination, said Sabra Botch-Jones, a forensic toxicologist and researcher at Boston University School of Medicine. Pre-washing the hair is “supposed to take away external contaminants or anything that would affect or impede analysis,” Botch-Jones said.
She added, however, that decontaminating a hair sample can be tricky, since cleaning procedures can vary depending on which drugs are being tested for. “You don’t want to perform so many wash steps that you destroy what you’re looking for.”
And sometimes, it might be impossible to wash drug residues from hair.
“You can wash it off, if it’s fresh,” said David Kidwell, a chemist and researcher who has been a paid consultant on court cases, including the Boston police case. “But if it sits there awhile, you can’t. Cocaine, in particular, degrades into the hair to the point where the hair can look like a drug user’s hair.”
The role of melanin
And different hair types bind drugs differently, some studies have found, due to the concentration of melanin, the pigment that darkens hair.
A 1998 study, for example, found that people with dark hair retained more cocaine in their hair than people with lighter hair colors. In that study, although all subjects had received the same dose of cocaine, “the non-Caucasians in this study had between 2 and 12 times as much [cocaine] in their hair as did Caucasians.” Another study, of hair samples mixed with cocaine in the lab, found that dark hair did bind more cocaine than light hair, but African-American hair was roughly the same in this regard as brown/black hair on white individuals.
A 2010 study concluded that “melanin content plays an important role in the degree of incorporation of morphine, codeine and their metabolites into hair.” That’s also true for amphetamines, suggested a 2012 study.
And African-American hair may be more likely to be damaged in such a way that the melanin is accessible.
“The cuticle [the outer part of the hair shaft] of African-Americans’ hair tends to be more damageable, and more damaged,” Kidwell said. “They put stuff on their hair, like emulsifiers and humectants, that allow the drugs in the environment to penetrate the hair more easily, especially if they’re making their hair straight with heat or chemicals.”
In the case of the Boston Police Department, more than four times as many black officers tested positive via the hair test, from 1999 to 2006, as did white officers—a figure that indicates “we can be almost certain that the difference in outcomes associated with race over that period cannot be attributed to chance alone,” the appeals court wrote in a 2014 decision on the case. However, the police department pointed out that no Asian-Americans on the force had ever had a positive test.
That decision sent the case back to the trial court, which ruled against the officers. It has now returned to the appeals court.
Sample said he is familiar with research finding hair testing to be discriminatory.
“I’m not sure I buy that,” said Sample. “I don’t believe those studies represent real-world conditions,” he said, pointing to the fact that many studies weren’t done on intact hair.
Sample acknowledged the melanin issue but said, “That’s not really an ethnic bias, but a hair-color bias, affecting dark hair. And it’s only for certain drugs, like cocaine.”
He insisted that the hair test does not discriminate. And a number of other court cases have found similarly, allowing hair testing to stand in job terminations and revocations of parole.
The question of the test’s accuracy is likely to take on even more relevance, however, as HHS considers whether to accept hair samples for federal drug testing programs. Public comment on the proposed rule by SAMHSA concluded in June 2015, and a final rule is forthcoming.
The technology of hair testing has dramatically improved, according to a presentation made by drug testing expert J. Michael Walsh to the group in 2013. “The methods have improved significantly over the last 25 years,” he told meeting attendees, according to a transcript of the presentation. “Lab performance has improved, the ability to detect small or minute amounts of drugs has improved with enhanced technology, and the criteria for what constitutes a positive test has also changed dramatically.”
Still, later in the presentation, he acknowledged high on the list of outstanding “scientific concerns” the issues of environmental contamination and hair color bias.
Some attorneys and scientists suggest that hair testing might best be used for clinical purposes, not forensic ones. Kidwell said that while hair testing might be useful in research, it’s less useful in deciding whether someone should get or keep a job.
“It’s best to use hair as a screening test and then follow up with urine testing,” he said. “And don’t take punitive measures based on hair testing.”