Illegal muscle-building drug found in some U.S. pork exports
Colin Henstock was reviewing hundreds of U.S. Department of Agriculture records, looking for evidence that workers had excessively beaten or shocked pigs at a North Carolina slaughterhouse, when he stopped short at one item: Last year, Mexican authorities had rejected pork exports from the same slaughterhouse because samples were contaminated with clenbuterol, a drug that in recent years has become trendy among actors, models, bodybuilders and dieters despite the fact it can lead to tremors, seizures and worse.
"I had to double-check that I was actually seeing what I was seeing," said Henstock, investigations project manager for People for the Ethical Treatment of Animals.
But it was right there in black and white on one of the 273 pages that Henstock received from the USDA's Food Safety and Inspection Service (FSIS) in response to his Freedom of Information Act request: On April 1, 2022, Mexican food safety officials notified their U.S. counterparts that the country had rejected chilled bone-in pork shoulder picnics because of the presence of clenbuterol. The pork had come from a slaughterhouse in Tar Heel, N.C., owned by Smithfield Foods, which is part of the Hong Kong-based WH Group, the largest pork company in the world.
In a follow-up FOIA request, Henstock learned that the shipments came not just from the Smithfield plant, but also from a facility in Worthington, Minn., owned by Swift Pork. It's not clear from the FOIA documents that PETA forwarded to The Washington Post how much pork these shipments represent, but in a February 2022 export certificate, FSIS notes that nearly 44,000 pounds came from the Smithfield facility alone.
The same FSIS document certified that the plant's animals at the time were inspected and found to be "sound and healthy."
Swift, a brand under JBS Foods, the second-largest pork producer in the world, did not return emails and calls for comment. Jim Monroe, vice president of corporate affairs for Smithfield, noted in an email to The Post: "We do not use clenbuterol anywhere in our production system and we are very confident in our food safety controls." U.S. government data support Monroe's claims, too, finding no clenbuterol in animal samples dating back years; experts also say the amounts of the drug found in the Mexican exports are probably too low to cause toxic effects in humans.
In 1998, the U.S. Food and Drug Administration approved clenbuterol, with a prescription, for horses with respiratory issues, but the agency did not approve it for animal husbandry or for human use. But because the drug has been shown to have anabolic properties, leading to decreased body fat and increased muscle mass, it has become popular with bodybuilders, models and celebrities who want to sculpt their figures. The drug, which is not illegal to possess in the United States, is easily purchased online. In 2006, CBS suggested clenbuterol was "Hollywood's dirty little secret" for female stars who felt pressure to drop 15 pounds to earn a part.
Livestock producers in countries where the drug is legal to use in animal agriculture like it for many of the same reasons that celebrities and athletes do: They say clenbuterol helps promote lean muscle growth while reducing fat and the amount of food eaten, a win-win for ranchers looking for bigger profits.
"Although the Commission of the European Community banned the use of this drug in animal feeding, the benefits to be obtained by increasing the ratio of lean to fat in the carcass by dosing the animals with black market supplies . . . must be tempting, since there have been a number of outbreaks of clenbuterol-related poisoning in the last 3 years in Europe," wrote the authors of a 1995 study.
For humans, clenbuterol's side effects can be serious, if not life-threatening. One study reported that people who took high doses of clenbuterol for weight loss or bodybuilding - sometimes 100 times higher than a typical therapeutic dose for respiratory problems - were admitted to critical care units with heart rates up to 170 beats per minute. "The medical literature contains numerous reports of patients with symptoms ranging from agitation and rapid heart rate all the way to heart attack and cardiac arrest," noted the nonprofit organization National Capital Poison Center.
In a 1992 outbreak of clenbuterol poisoning in Spain, researchers interviewed 113 patients in and around Sabadell in Catalonia who had been treated for muscle tremors, muscle pain, increased heart rate and headaches. They found that 91 of the 113 people had gone to a hospital emergency room for evaluation. A urine analysis collected from 47 of the patients showed that all had traces of clenbuterol, ranging from 11 to 486 parts per billion. Every patient recovered.
In the same study, researchers tested liver samples from the restaurant and company canteen suspected of serving the tainted meat. In the samples that tested positive, the amount of clenbuterol ranged from 19 to 5,395 parts per billion.
By comparison, the tainted meat stopped at the Mexican border had lower amounts: The Smithfield sample had 7.22 parts per billion of clenbuterol, while the Swift sample had 16.51 ppb. Aside from the pork shoulders, it's not clear from the FOIA documents what other types of meat the Mexican officials tested given only one plant's shipment was identified. Experts say liver samples usually have higher amounts of clenbuterol because the drug tends to concentrate in the organ.
The amounts found in the Mexican samples would probably be "below what would have any significant physiological effect" in humans, said Matthew Fedoruk, chief science officer with the U.S. Anti-Doping Agency. But, he added, "it's really a case of what types of meat, how much meat you're eating, how the meat's been treated and a whole bunch of factors that might play into whether it has any effect to the individual that is unknowingly consuming the clenbuterol."
The U.S. and world anti-doping agencies have been monitoring clenbuterol for years. Athletes around the globe - boxers, Olympic athletes, soccer players and even a Tour de France winner - have tested positive for clenbuterol. Many have claimed they were not trying to gain a competitive advantage but were simply victims of contaminated meat. The World Anti-Doping Agency has prohibited clenbuterol in and out of competition; the U.S. Anti-Doping Agency enforces the WADA rules.
But because ranchers in some countries use clenbuterol in animal agriculture, whether it's legal or not, athletes can unknowingly consume tainted meat. Fedoruk says the U.S. Anti-Doping Agency advises athletes to avoid meat from unknown sources when competing in countries where clenbuterol can be used in animal feed; the agency, Fedoruk adds, will even advise athletes to keep a dietary log and consider alternative protein sources in high-risk countries.
"We specifically warn athletes about Mexico, Guatemala and China, but that's not an exhaustive list," Fedoruk said. Clenbuterol is prohibited from use in animal husbandry in Mexico.
The risks are "much lower" in the United States and Europe, he said, because even meat imported from, say, Mexico is "more stringently screened than the meat that might be available in those high-risk countries for domestic consumption." The agency also monitors USDA records and talks with experts to keep track of meat potentially tainted with clenbuterol.
"We haven't seen the illegal use of clenbuterol for animal husbandry in the U.S.," Fedoruk said. "It's not something that is used, because there are more affordable, available and safer alternatives to give livestock in the U.S.," including ractopamine.
Statistics from the U.S.'s food inspection service would appear to support Fedoruk's point. The National Residue Program screens beef and pork for beta2-adrenergic agonists, including clenbuterol, relying on a multipronged approach that includes random surveillance sampling and "inspector-generated sampling when they suspect that animals may have violative levels of chemical residues," according to the agency. Between 2013 and 2023, according to an FSIS spokeswoman, the National Residue Program analyzed more than 53,600 domestic beef and pork products for the presence of clenbuterol - and zero samples tested positive.
But Henstock finds little comfort in those numbers since, as he points out, tens of millions of hogs are slaughtered annually in the United States. Last year, according to USDA statistics, more than 125 million hogs were slaughtered.
"The public here should be aware that this incident happened and that our federal officials failed to detect it until the Mexican government detected it for them and alerted them to it," Henstock said.
It's not clear how the pork at the Mexico border became contaminated. FSIS conducted inquiries into the two facilities implicated in the tainted pork.
The meat from the Smithfield plant in North Carolina was from animals slaughtered on Feb. 2, 2022, according to the FOIA documents that PETA obtained. Smithfield contacted its live animal suppliers who said that clenbuterol is not used in its production system, and the company provided staff nutritionist and veterinary letters to support the claim. But the company was not able to provide "monitoring records to support [that] the animals they receive are free of clenbuterol," according the document.
Last year, FSIS also collected three samples from the Smithfield plant, one from Feb. 1, March 22 and March 28. All of them tested negative for clenbuterol, documents show. What's more, an agency spokeswoman said, the Smithfield facility has never had National Residue Program samples that tested positive for clenbuterol, before or after the contaminated meat found in Mexico. FSIS has not been able to identify the source of the tainted pork from the Smithfield plant.
Officials from the Swift plant in Minnesota performed a risk analysis, according to the FOIA documents, and "concluded that non-traditional hogs (i.e., hogs from fairs or shows) may have been inadvertently mixed in with the market hogs they received. The non-traditional hogs may have been fed clenbuterol."
FSIS has not yet been able to determine a "root cause" of the tainted pork from the Swift plant, the agency spokeswoman said.
Part of PETA's goal in releasing its FOIA documents to the public is to promote a vegan diet, which is considered to be better for the environment, not just for the animals, Henstock noted. But the group also cares about human health, he said, which is why PETA is not reassured by the USDA, whose mission includes not just protecting the food supply, but also promoting U.S. food producers.
The negative test results don't "change the fact that there was clenbuterol that Mexican authorities found in their meat," Henstock said, "and it doesn't necessarily guarantee that there aren't other producers out there giving it to their animals."
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