(a) The regulations in this part provide a means to minimize the use of intoxicants by merchant marine personnel and to promote a drug free and safe work environment.

(b) These regulations prescribe the minimum standards, procedures, and means to be used to test for the use of dangerous drugs.

(c) As part of a reasonable cause drug testing program established pursuant to this part, employers may test for drugs in addition to those specified in this part only with approval granted by the Coast Guard under 49 CFR part 40 and for substances for which the Department of Health and Human Services has established an approved testing protocol and positive threshold.