Federal rules allowing for an alternative to mandatory urine drug tests of truck drivers just took another step closer to becoming reality.

The Substance Abuse and Mental Health Services Administration (SAMHSA) of the Department of Health and Human Services has proposed new hair testing guidelines. SAMHSA published the guidelines in the Federal Register, starting a timeframe for public comments, ending Nov. 9.

This move follows the agency’s release of technical standards for hair and oral fluid drug testing of safety-sensitive workers. Since federal drug testing of truck drivers began in 1991, SAMHSA has set the technical protocols for drug tests. This includes driver urine tests as required by Federal Motor Carrier Safety Administration (FMCSA) regulations.

Once SAMHSA finalizes this proposal and introduces it into federal regulations, U.S. Department of Transportation (DOT) agencies, including the FMCSA, will need to develop their own rules for implementing mandatory hair drug testing.

Many contend that hair testing is more accurate than the current urinalysis tests. While urinalysis can reveal drugs used in the past one to three days, hair testing can uncover repeated drug use up to 90 days. For that reason, several motor carriers already use hair testing even though it comes at added expense.

However, until DOT accepts hair tests, motor carriers cannot share hair test results with other carriers or with the FMCSA Drug and Alcohol Clearinghouse. That means carriers that use hair tests must continue to conduct urinalysis tests to meet DOT requirements.

This latest SAMHSA proposal does not meet the outcome desired by some motor carriers because a hair test would need to be paired with a second test via urinalysis (or an oral fluids test when adopted by the agency) to confirm results. So, two tests would still be required, as is the case now for those carriers who voluntarily conduct hair tests.

The two-test approach was chosen by SAMHSA to overcome legal issues raised in hair testing lawsuits. Hair is subject to external contamination and can be affected by personal grooming, such as hair coloring, and hygiene practices. Those factors could influence hair test results, though washing, rinsing and decontamination techniques developed by drug testing labs may address them.

A more complex legal issue concerns natural hair color, or pigmentation. Studies have shown that hair color can affect the absorption and retention of certain drugs. Black hair and brown hair more readily retain evidence of drug use than red and blonde hair. The prevalence of black and brown natural hair color in certain ethnic groups has raised concern over effective discrimination in hair testing results.

Because of possible external contamination and the effect of natural hair color, SAMHSA proposes the second urinalysis test to confirm results. The only exception is testing for marijuana use which does not appear to raise these concerns, according to scientific research. In this case, SAMHSA would allow a hair test that is positive for marijuana use to stand by itself.

Finally, SAMHSA proposes allowing hair testing only for pre-employment and random drug tests. SAMHSA says that drugs require five to seven days to become evident in hair, so hair tests may not reveal current or recent drug use. Hair testing would therefore not be effective for post-crash or reasonable suspicion circumstances.

Critics say the SAMHSA proposal effectively negates the value of hair testing, which is to uncover the “lifestyle” drug user. Urinalysis and oral fluid testing only reveal recent drug use. Persons who take a urinalysis or oral fluids test to confirm hair test results would fail only if they were also a recent drug user. That result is no different than today, where urinalysis is the only test given. But a urinalysis or oral fluids test will not confirm evidence of long-term drug use. So, the opportunity to improve highway safety by eliminating the long-term drug user would be lost, according to critics.

SAMHSA requests public comments on all these issues, emphasizing its reliance on scientific research.