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(CNN) — China’s ban on certain chemicals is being credited by Drug Enforcement Administration officials in a noticeable decrease in certain synthetic drugs in the United States.

Police encounters with six substances that were part of China’s 115-chemical ban have dropped dramatically (PDF) since it took effect in October, DEA numbers show.

Synthetic cannabinoids — commonly known as K2 or spice — stimulants similar to cocaine or MDMA and the notoriously dangerous synthetic known as flakka have fallen dramatically from they were last summer.

Flakka has all but disappeared from Florida, where it was wreaking havoc.

“We’ve definitely seen a significant decrease, especially of flakka,” Broward County Sheriff’s Lt. Ozzy Tianga said.

As a result, DEA officials say, they are optimistic that ongoing meetings with their Chinese counterparts can continue the trend. This month, 14 high-ranking DEA officials spent a week in Beijing and two other Chinese provinces, where they talked about how to work together to tackle the problem of Chinese chemists making and selling dangerous synthetic drugs in the United States.

DEA spokesman Russell Baer called it an “unprecedented dialogue between the two countries.”

China now faces a problem similar to one the United States has been struggling with: how to keep up with chemists who are constantly tweaking formulas to stay one step ahead of the law.

Tianga said he anticipated that new synthetics would show up in place of those banned, and officials have seen some of that, but the numbers have been nothing like last summer, when flakka use was at an alarming high.

“Overall, [synthetics have] significantly dropped since the ban — at the epicenter here in South Florida,” Tianga said. “But by no way are we out of the woods. There will be more molecular changes to substances that will be introduced to society.”

In Florida this summer, the Legislature approved and the governor signed a blanket ban of substances that have no practical use other than to get high.

Baer said the DEA is continuing to work with Chinese officials on a similar ban as they now battle a nationwide problem with synthetic fentanyl.

“They talked about continuing efforts to try to understand each other’s perspective of this problem,” he said. “Historically, we have not been able to talk about this stuff. We’ve now gotten to the point that China is listening to us and addressing some of the [drug] scheduling issues. They are their own country, and they have their own concerns. One [problem] people don’t understand is that China has an extensive commercial manufacturing program over there. These illicit substances … are a small part of that huge legitimate industry.”