If you eat meat in any country in the European Union, or even in China or Russia, you don’t have to worry about getting a dash of ractopamine with your pork or beef. All these nations ban the use of the growth-promoting drug.

But if you eat meat in the United States, buyer beware. Ractopamine may be unsafe for you. The drug is certainly unsafe for pigs and other farm animals dosed with it. It has caused hundreds of thousands of pigs to become lame or unable to walk without intense pain, or die.

Pork producers feed pigs ractopamine during the last few weeks before they are sent to the slaughterhouse. It alters the pigs’ metabolism so that 10 percent more of the food they eat turns into muscle. That translates into faster growth and leaner meat.

Eli Lily & Co’s Elanco Animal Health unit, the leading producer of ractopamine-based livestock drugs, said in a statement to Reuters last year that it remains confident in its products’ safety and the FDA’s approval process. The drug was originally approved by the FDA in 1999.

Beef producers are also flocking to ractopamine, according to Fortune magazine, after major meat packers refused to accept cattle doped with a similar muscle-building drug, Zilmax. Led by Tyson Foods and Cargill, the packers stopped accepting cattle treated with Zilmax in late 2013 after finding that the cattle were arriving at their slaughterhouses “hoofless” and in severe pain, according to a Reuters special report.

A March 2014 report from Texas Tech University and Kansas State University  found that during cattle’s lives “the incidence of death was 80 percent greater in animals administered [Zilmax].”

Since the major packers stopped accepting cattle treated with Zilmax, the drug’s manufacturer, Merck, has begun studies to show the drug is safe and can go back on the market. But the packers have so far refused to go along. Not only do they say it causes animals to suffer; it also would prevent meat sales to foreign nations that ban use of the drug.