WASHINGTON, D.C. — So-called "recreational' use of marijuana may have been legalized in some states, but the drug remains forbidden for safety-sensitive transportation employees — including school bus drivers — federal officials said.

In the November elections, Colorado and Washington state passed initiatives to allow recreational marijuana use. However, it is still an illegal drug under federal law.

On Monday, the Department of Transportation's (DOT) Office of Drug and Alcohol Policy and Compliance issued a notice to clarify that those state initiatives will have no bearing on the DOT's regulated drug testing program.

Medical review officers will not verify a drug test as negative based on learning that the transportation employee used marijuana recreationally in those states that allow such use, DOT officials said.

The agency also reiterated that the same holds true for transportation employees in states that have passed "medical" marijuana initiatives.

"It remains unacceptable for any safety-sensitive employee subject to drug testing under the Department of Transportation's drug testing regulations to use marijuana," Jim Swart, director of the Office of Drug and Alcohol Policy and Compliance, said in the notice.

Marijuana is still a Schedule I drug under the Controlled Substances Act. The DOT's Drug and Alcohol Testing Regulation — 49 CFR Part 40 — does not allow the use of Schedule I drugs for any reason.

Swart said in the clarification notice that his office had gotten several inquiries about whether the state marijuana initiatives would impact the DOT's drug regulation for safety-sensitive transportation employees, which also includes pilots, truck drivers, train engineers, subway operators and ship captains, among others.

"We want to assure the traveling public," Swart said, "that our transportation system is the safest it can possibly be."