Carfentanil, an opioid said to be 100 times more powerful than fentanyl, has been tied to at least 700 deaths in numerous states. Worst hit include Michigan, Florida, and Ohio, according to data compiled by US authorities. Carfentanil was originally intended to sedate large animals, such as elephants, and is known to be 10,000 times more powerful than morphine, according to the DEA.

Even a minute trace of carfentanil can be deadly because it can be absorbed through the skin or inhaled as an airborne powder. Drug dealers often mix carfentanil with heroin and other opioids and sell it to unsuspecting users, according to the DEA. Profit is a likely motive, since the powerful opioid is relatively inexpensive.

Carfentanil production has been tied to China, which recently promised a crackdown on the export of the drug. This would follow China’s action on fentanyl, which continues to stream into the US because Mexican cartels are producing it and shipping it north.