Some of the world's biggest restaurant chains have taken major steps to voluntarily limit the use of antibiotics in their supply chains. Customers trying to understand these new policies might need to acquire a taste for trust.

McDonald's announced plans for changes in its chicken supply a year ago in the United States and Europe. Subway pledged to serve only meat and poultry raised without antibiotics by 2025 in its U.S. restaurants. Panera Bread, which has served chicken raised without antibiotics since 2004, and Chipotle Mexican Grill, which stepped back from its original "no antibiotics ever" after encountering pork-supply shortfalls, have been chain-restaurant trendsetters.

The moves come in response to a public-health problem-antibiotic-resistant illness in humans has been declared a global crisis by the World Health Organisation-as well as increasingly vocal calls from consumers to get antibiotics out of supply chains.

Into the quest for fewer antibiotics in our fast food comes Domino's Pizza Group, the independent British branch of the international pizza-delivery giant. The company last month told the media, in response to a campaign from a group of large investors, that it has stringent limits on antibiotics usage.


Domino's suppliers in the U.K., explained spokeswoman Nina Arnott, "use antibiotics only when necessary to treat disease" and while "under strict veterinary supervision."

That might sound like a common-sense approach but it stands in marked contrast to the way most meat and poultry suppliers routinely treat animals with medicine to defend against illness and encourage growth. It was also unusual that Domino's Pizza Group chose to quietly disclose the change in response to the investor campaign, rather than making the shift to meat from animals raised without antibiotics part of its consumer marketing.

The decision by Domino's to regulate its British supply chain is exactly the kind of policy advocates would embrace, and it would appear to be a much higher standard than the practices at its American counterpart. Just last year, a coalition of nonprofits that includes the Natural Resources Defense Council gave Domino's in the United States a failing grade for lacking any clear policy on antibiotics, although the company says it disagrees with the grade.

The sudden shift points to thorny question: When a food company pledges to follow self-imposed supply rules, how can the people opening a pizza box really know that the pepperoni is different?

Even for companies that are more assertive in touting new, cleaner products at their restaurants, information as to how they plan to get there and who will make sure they're doing what they promise can be murky at best. No single regulatory authority monitors these claims. The level of outside verification and the information made available to customers varies widely from chain to chain. When the policies cross borders, auditors don't necessarily follow. A major fast-food chain making a claim about antibiotic use is, for the most part, asking customers to simply take the company's word for it.

"Claims are subtly different at the retail chains, and there's no public verification process of the producer claims," said David Wallinga, a senior health officer at NRDC. The U.S. Department of Agriculture has a program, Certified Responsible Antibiotic Use, for poultry, but it doesn't cover other animals. Since the USDA program allows for veterinarian-supervised, limited use of medically important antibiotics to treat disease, it is less restrictive than many of the corporate commitments made thus far.

"There really are as many ways of doing this sort of thing as there are people doing it," said Martin Cooke, international head of corporate engagement at World Animal Protection, an animal welfare group.

Some companies fill the regulatory void with auditing. Panera, for example, uses SAI Global to perform proprietary audits on producers. Chipotle has an auditing system, although the company did not respond to requests to discuss its auditor. For its U.S. restaurants, Subway uses a franchisee-owned purchasing cooperative to verify supplier practices. Domino's Pizza Group said only that it has close relationships with-and regularly reviews-suppliers and has "robust approval processes," but it wouldn't elaborate.

In the U.S., McDonald's said that it will use the USDA's Process Verified Program to assure that medically important antibiotics are not used in its chicken supply chain. That program allows the company to set its own processes, checkpoints, and requirements but has the USDA verify that they're being implemented. In Europe, however, McDonald's relies on an internal verification system.

What it means to limit or eliminate antibiotic use by food suppliers isn't always clear. These corporate policies cover a wide variety of drugs used for a smattering of reasons, with no universal regulatory standards. Does a pledge to do away with antibiotics cover all drugs in the category or just those deemed important to human health? Can antibiotics be used in any circumstance, aside from treating disease? Many animals in the global food supply are routinely fed antibiotics as a preventative measure or to produce bigger animals on less feed, practices that are loudly criticized by public health advocates.

Europe has already banned antibiotics for growth promotion, and the European Parliament may soon vote to ban routine use for disease prevention. In the U.S., however, compliance with FDA guidelines on these practices remains voluntary. Sales of antibiotics for use in animals still accounts for 62 per cent of medically important antibiotics (PDF) in the U.S. and 44 per cent in Britain (PDF), according to the latest counts, even while research clearly links agricultural overuse (PDF) to increasing drug resistance for humans.

Domino's U.K. operation is that nation's largest pizza chain, according to data from Euromonitor, and it provides no information about antibiotics on its website. There was no press release or other marketing effort to laud its policy, leaving some observers flummoxed. "It is curious that they're not more public about their point of view on it," said Aaron Allen, a restaurant consultant and analyst at Aaron Allen & Associates. "There's nothing to show how they got to where they're at."

In response to questions from Bloomberg, Domino's Pizza Group said in an email that it works with "a small number of large and well-established suppliers," naming two specific suppliers:

• Tulip sells mostly pork to customers such as Chipotle and said that "critically important antibiotics are only used as a 'last resort.'"

• Glanbia Cheese Ltd. is a major mozzarella seller in Europe and sources milk from farms in Wales that adhere to the Red Tractor Farm Assurance standards, which allow only for antibiotics to treat sick animals. Cheese made without following the standard "will result in a failed antibiotic test at arrival on our site and render the farmer liable for the cost of disposal of the entire tanker of milk," said Pete Brain, director of quality assurance at Glanbia.

Domino's Pizza Group declined to discuss its supply chain in more detail. The problem for the pizza chain and other chains is stitching together multiple suppliers who follow a stricter policy. Duncan Fox, a Bloomberg Intelligence analyst focused on consumer food, noted that it would be dangerous to rely on only one provider for a vital pizza ingredient such as cheese. "If they have a problem in the factory," he said, "then your whole supply chain is gone wrong."

Even as Domino's and other large food chains move toward stricter standards, there's little evidence of a decline in overall agricultural use of antibiotics. A December 2015 report from the Food and Drug Administration found antibiotics sales for farm animals still on the rise in the U.S., up 22 per cent from 2009 to 2014. Global use, meanwhile, is expected to rise 66 per cent by 2030.

"How companies are managing these risks are very pertinent information for investors," said Grace Hetherington of ShareAction, which coordinated a recent investor campaign against overuse of antibiotics alongside Farm Animal Investment Risk & Return, a nonprofit group. "What's the point of having that policy," she asked, "if you can't prove how you're implementing it?"