When pigs eat feed with a drug called ractopamine for a month, the drug builds up way more in their kidneys and liver—organs that clean and process toxins—than in their meat, fat, or blood. This means their body is working hard to get rid of it, so it doesn’t stay in the meat you eat.

When pigs are given a specific drug called ractopamine for a week, the drug shows up way more in their pee than in their meat or blood—so much so that testing their urine is the best way to tell if they’ve recently been given this drug.

When farmers stop giving pigs a drug called ractopamine, the leftover traces in the meat disappear quickly—so fast that by the time the pig is slaughtered, there’s hardly any left, and it’s under the safety limits set by regulators.

Pigs were fed a growth-promoting drug called ractopamine for 28 days, and even when they were slaughtered the same day the drug stopped, tests showed no dangerous levels of the drug left in the meat — so regulators say it’s safe to eat right away.

When guinea pigs were given a specific drug called ractopamine every day for a week, the drug stayed longest and in the highest amount in their lungs the day after they stopped taking it—much more than in their muscles, which had almost none.