LA CROSSE, Wis. (WKBT) -

A new and extremely dangerous opioid is causing concern among emergency physicians in our area.

Carfentanil is a synthetic opioid approximately 1,000 times stronger than heroin, and 10,000 times more potent than morphine. According to the Associated Press, 12 Chinese businesses have said they would export the drug to the U.S.

This new drug is being mixed-in with other opiates, such as heroin, because it is often times a cheaper alternative.

"This is what they use to sedate and use for pain control for very large animals. So this has been around for a very long time, we've never used it in humans because it was too potent and the margin of error is just too small,” said Gundersen Health System Emergency Physician Chris Eberlein, MD.

Despite the dangers, carfentanil is not a controlled substance in China. It is legally manufactured within the country and sold online. The U.S. is pressing China to blacklist the drug, but Beijing has yet to act.