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Hair raising results

By Dr. Doug Voss

Skyrocketing insurance rates driven by nuclear verdicts have led trucking companies to place an even greater emphasis on shoring up their safety performance.  According to Broughton Capital, LLC, insurance rates are responsible in part for a three-fold increase in trucking company bankruptcies during the first half of 2019 as compared to the same period in 2018.  Safety is a matter of life and death on the road and also threatens your company’s survival.

Maintaining a drug-free driver workforce is key to safety performance.  Many carriers use more stringent hair follicle drug tests in addition to the federally recognized urinalysis to help ensure driver sobriety.  Last summer, Freightwaves published an article based on research by the Trucking Alliance, which indicated that as many as 300,000 current drivers would not be on the road if they were forced to pass a hair test.  Using 151,662 paired pre-employment urine and hair drug screenings from fifteen (15) different trucking companies, some of whom are Arkansas-based, their results indicated that 949 (0.6%) applicants failed the urine test and 12,824 (8.5%) failed or refused the hair test. FMCSA classifies refusal to submit to a drug or alcohol screening as a failure. This yields a hair test failure rate 14.2 times larger than urine. The safety implications of this are astounding but so are the potential operational impacts when the Federal Drug and Alcohol Clearinghouse gets up to speed. 

Dr. Cangelosi and I conducted two rounds of research related to these findings.  First, we determined whether or not the sample was representative of the broader U.S. driver population by comparing sample drivers’ state of licensure to the number of truck drivers employed in each state as provided by the Bureau of Labor Statistics (BLS).  A perfect, positive correlation would equal 1.0. We found a highly statistically significant correlation of 0.88 with the analogous BLS driver pool.  Given a 1% margin of error and a 99% confidence level, we determined that the sample was representative and of sufficient size.  This supports the notion that 300,000 current drivers would be unable to pass a hair follicle drug screen. 

Some critics argue against hair testing because they claim it is biased against certain ethnic groups based on hair type differences.  Our second round of research examined whether or not this is the case.  Three carriers in the sample independently provided us with over 70,000 paired urine and hair test results as well as the identified ethnic background of drivers who took the tests.

We utilized two methods to uncover possible disparate impacts resulting from hair testing.  First, we subjected urine and hair pass/fail rates to the federally recognized 4/5’s rule (CFR Title 29 – Uniform Guidelines for Employee Selection Procedures), which assumes disparate impact if any ethnic group does not pass at a rate of at least 80% of the rate of the ethnic group with the highest passing rate.  Second, we utilized a well-established statistical method called chi-squared difference tests to assess whether significant differences exist between ethnic groups within each type of drug test. 

Results in each test met the required 4/5’s Rule threshold, which indicates equal treatment of ethnic groups for both urine and hair testing.  Chi-squared results indicate ethnic groups have significantly different pass/fail rates for both urine testing as well as hair testing.  In other words, ethnic groups are significantly different irrespective of testing procedure.  Given these findings, we were unable to uncover evidence of disparate impact among ethnic groups resulting from the use of hair tests.  Factors other than testing methodology seem to underly ethnic groups’ pass/fail rate differences.

Nobody wants to get the call that their driver has been involved in a reportable safety event.  Hair testing is a powerful tool that can help prevent such incidents or lessen your potential liability when they occur.  Ask yourself, how many of your drivers could be included in the 300,000 that would be unable to drive if forced to pass a more stringent drug test?  The answer may be hair raising.


Dr. Doug Voss is a professor of logistics and supply chain management at the University of Central Arkansas. Voss also serves on the Arkansas Trucking Association Board of Directors. His research partner, Dr. Joe Cangelosi, is a professor of marketing at the University of Central Arkansas.

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