[Code of Federal Regulations] [Title 49, Volume 1] [Revised as of October 1, 2006] From the U.S. Government Printing Office via GPO Access [CITE: 49CFR40.89] [Page 652] TITLE 49--TRANSPORTATION Subtitle A--Office of the Secretary of Transportation PART 40_PROCEDURES FOR TRANSPORTATION WORKPLACE DRUG AND ALCOHOL TESTING PROGRAMS--Table of Contents Subpart F_Drug Testing Laboratories Sec. 40.89 What is validity testing, and are laboratories required to conduct it? (a) Specimen validity testing is the evaluation of the specimen to determine if it is consistent with normal human urine. The purpose of validity testing is to determine whether certain adulterants or foreign substances were added to the urine, if the urine was diluted, or if the specimen was substituted. (b) As a laboratory, you are authorized to conduct validity testing. [65 FR 79526, Dec. 19, 2000, as amended at 66 FR 41951, Aug. 9, 2001]