(a) Except as provided in paragraph (b) of this section, employers subject to this part shall use only laboratories certified under the DHHS “Mandatory Guidelines for Federal Workplace Drug Testing Programs,” April 11, 1988, and subsequent amendments thereto.

(b) Employers subject to this part may also use laboratories located outside the United States if—

(1) The Department of Transportation, based on a written recommendation from DHHS, has certified the laboratory as meeting DHHS laboratory certification standards or deemed the laboratory fully equivalent to a laboratory meeting DHHS laboratory certification standards; or

(2) The Department of Transportation, based on a written recommendation from DHHS, has recognized a foreign certifying organization as having equivalent laboratory certification standards and procedures to those of DHHS, and the foreign certifying organization has certified the laboratory, pursuant to those equivalent standards and procedures.