40.159—What does the MRO do when a drug test result is invalid?

(3) After explaining the limits of disclosure (see §§ 40.135(d) and 40.327 ), you must determine if the employee has a medical explanation for the invalid result. You must inquire about the medications the employee may have taken.
(4) If a negative result is required (i.e., pre-employment, return-to-duty, or follow-up tests), follow the procedures at § 40.160 for determining if there is clinical evidence that the individual is an illicit drug user.
[65 FR 79526, Dec. 19, 2000, as amended at 73 FR 35972, June 25, 2008; 75 FR 49863, Aug. 16, 2010]