In the coming months, a few shoppers will encounter a new and unfamiliar phrase when looking at packages of pork: “Produced without the use of ractopamine.”

It’s the brainchild of David Maren, founder of Tendergrass Farms, which sells pork products from pigs raised the “all-natural” way, on pasture.

Maren first heard about ractopamine years ago, when he was just getting into this business. Maren was talking with his cousin, who raises pigs the conventional way, in big hog houses.

“At one point I mentioned to him something like, ‘Well, I know you use hormones to raise your pigs, and that’s why they grow so fast,’ ” recalls Maren. “And he said, ‘No! Hormones are illegal in pork production in this country. We don’t use hormones and we never have.’ “

Then his cousin added, “We do use ractopamine.”

Maren had never heard of this drug. “It’s not something that I hear anybody talking about,” he says.

This is odd, he says, because ractopamine is a very big deal in the pork industry. Most pigs in America get this drug, because it’s extremely effective. It’s a “beta agonist” and has effects that are similar to adrenaline. It gets a pig to put on more muscle, instead of fat, and also put on weight more quickly. That’s money in the farmer’s pocket: According to some experts, it adds two or three dollars of income per pig.

The Food and Drug Administration says that ractopamine is safe. The agency approved its use in pigs in 1999.

But the drug still arouses some controversy. Safety regulators in the European Union, China, Russia and a variety of other countries have not approved the drug. They say there’s not yet enough evidence to prove that pork produced using ractopamine is safe to eat.

Apart from any human health concerns, there have been many reports of animals suffering when they get too much of the drug.

There are pigs that don’t get any ractopamine. Organic pork producers definitely don’t use it. Natural pork producers probably don’t — although Maren says that there’s so little awareness of ractopamine use that many big buyers of “all-natural” pork don’t even bother to ask about it.

And consumers don’t get any information about all that on pork labels. It’s never mentioned.