Military members are nearly twice as likely to use synthetic marijuana as the natural version. But until now, the synthetic drug - six to 10 times more potent than the weed itself - was much less likely to be detected because the Navy didn't routinely screen for the drug.
That all changed last month when Navy laboratories began randomly testing for synthetic marijuana during drug screenings.
Navy officials hope the effort - part of its zero-tolerance policy for drug use - will have a significant impact.
"We are widening our fishnet to detect more drugs of choice," said Lanorfeia Parker, the deputy director of the Navy's alcohol and drug abuse prevention program.
The Department of Defense estimates that 1 percent of military personnel may be using synthetic marijuana, or "spice," compared with 0.64 percent of all military personnel - and 0.43 percent of active-duty personnel - using ordinary marijuana.
In the past, commanders wishing to screen for the drug had to make a special request, and the Navy would send those urine samples to a Department of Defense lab for testing, Parker said.
Now, by including the synthetic screen as part of automatic, random testing conducted by the Navy's three main laboratories, the service hopes to make the drug far less enticing for sailors.
"We do know it is being used, and we know that the civilian sector is seeing more use, as well," Parker said. "Because of the prevalence, we have to take action to incorporate it into our standard panel."
The Navy first acknowledged spice, often known by the brand names Spice or K2, in its drug policy in 2010, citing the "emerging popularity of designer drugs."
But it wasn't until March 2012 that the Armed Forces Medical Examiner System created a definitive test for the synthetic substance, because its chemical mix often changed. During that interval, use of the drug increased among the rank-and-file, Parker said: "A lot of sailors moved to synthetic because they believed we weren't testing for it."
Since then, the Navy has dismissed hundreds of sailors in its crackdown on spice, including 11 aboard the amphibious assault ship Wasp who were discharged as a group in November 2012 for using the drug.
In mid-December, Navy labs got their own ability to test for spice along with other drugs.
Parker said the Defense Department provided the Navy with a million cannabinoid test kits and that they'll be used randomly during drug-testing.
"This is just the start," Parker said.
"As we continue to progress, we are hoping to increase the number."