CHICAGO (CBS) — What federal agents call “a whole new level” of synthetic marijuana and methamphetamine, some with potentially deadly side effects, are being found in packages and letters coming through the international mail facility at O’Hare.

“Our CBP officers have found these shipments arriving from China and Europe, manifested as various chemicals, white powders, or natural plant materials,” Steven Artino, acting director of CBP Field Operations in Chicago said in a statement.

“These unpredictable chemical combinations are sending some users to the hospital and others to the grave,” he said.

Federal narcotics regulations are being broadened to cover these substances, even as chemists in Europe and Asia work to concoct and sell new variations over the internet, hoping to circumvent narcotics classifications, according to U.S. Customs and Border Protection.

In recent months, chemists in Chicago have identified three new imported synthetic marijuana and methamphetamine compound derivatives, a release from CBP said..

“We are seeing a whole new level of synthetic highs coming to America,” William Wagner of the Chicago CBP Laboratory said in a statement.

“Our CBP chemists have tested hundreds of samples and uncovered emerging trends in the increase in variations of synthetic marijuana, bath salts and other synthetic drugs.”

Many of these synthetic compounds can be 100 to 800 times more potent than the original, according to Wagner. “Upon ingestion, side effects can include elevated heart rates, paranoia, vomiting, severe agitation and hallucinations. It is simply unsafe to take these unknown drugs.”

(Source: Sun-Times Media Wire © Chicago Sun-Times 2012. All Rights Reserved. This material may not be published, broadcast, rewritten, or redistributed.)