How Does an MRO Review an Adulterated or Substituted DOT Drug Test?

Under 49 CFR 40.145(a) and (b), the MRO treats a laboratory report of an adulterated or substituted specimen the same way as a confirmed positive for a drug or drug metabolite and follows the same verification procedures, including contact with the employee. In the verification interview, the MRO explains the laboratory findings, addresses technical questions the employee raises and offers the employee the opportunity to present a legitimate medical explanation.

Under 40.145(e), the employee has the burden of proof. For an adulterated specimen, the employee must show that the adulterant entered the specimen through physiological means. For a substituted specimen, the employee must show that he or she did produce or could have produced urine through physiological means meeting the substitution criteria in 49 CFR 40.88(b). The information is presented at the interview, and the MRO may extend the time by up to five days when there is a reasonable basis to believe the employee can produce relevant evidence. Under 40.145(f), the MRO and the employer are not responsible for arranging, conducting or paying for studies or examinations.

If the explanation does not present a reasonable basis for a legitimate medical explanation, the MRO reports a verified refusal to test because of adulteration or substitution. If it may present a reasonable basis, the MRO directs the employee to obtain a further evaluation within the five-day period from a referral physician acceptable to the MRO. The final choice of physician is the employee's, and any additional drug tests must be performed in an HHS-certified laboratory. If the MRO finds a legitimate medical explanation, the MRO cancels the test and informs ODAPC in writing. Otherwise, the MRO reports a verified refusal to test.

Under 40.145(h)(1)(ii), an assertion that personal characteristics such as race, sex, weight, diet or working conditions caused a substituted result does not, in itself, constitute a legitimate medical explanation.

Refusals are covered in What Counts as Refusing a DOT Drug Test?. Split specimen requests are covered in How Does a Split Specimen Test Work after a Positive DOT Drug Test?, and explanations an MRO cannot accept in What Explanations Can an MRO Not Accept for a DOT Drug Test Result?.

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