Penn research reveals drug-tainted milk finds its way to consumers

For dairy farmers in Peru, who may own only three or four cows, each pint of milk their animals produce represents precious income. When one of those cows is given antibiotics to treat an infection and its milk must be discarded for several days until the drug clears its system, the farmers can find themselves in a financial bind.

Over seven months in 2012 and 2013, Laurel Redding, a graduate student in Penn’s VMD/Ph.D. program in the School of Veterinary Medicine and the Perelman School of Medicine, traveled around Cajamarca, an important dairy-producing region in Peru’s northern highlands, to try to shed light on what has the potential to be an important public health issue.

“In many parts of low- and middle-income countries, the majority of the population is employed on small farms,” she says. “But we really don’t know a ton about antibiotic use on those farms.”

In dairy cows, antibiotics can prove extremely useful for preventing and treating infections, leading to improvement in overall health and productivity. Yet their use promotes the rise of resistant strains of bacteria on farms, putting workers at risk of contracting difficult-to-treat infections. And if drug-tainted milk makes its way to consumers, allergies, toxicity, and antibiotic resistance can result.

Working with the nonprofit organization Foncreagro, Redding surveyed dairy farmers, veterinarians, and others involved in the dairy industry to find out how widespread antibiotic use was, how educated farmers were about using drugs in their animals, and how much of those drugs were making their way into the milk and milk products consumed by people in the area.

“The takeaway message from my study was kind of a good news-bad news situation,” Redding says.

The good news was that overall, antibiotic use on the farms was relatively low. She also found that the farmers knew about the risks of using these drugs.

The bad news was that the farmers often ignored these risks and continued selling milk from treated cows to milk processing companies. Redding’s research revealed that, of the farmers treating their cows with antibiotics, 92 percent continued selling the treated cows’ milk.

She says a system of incentives and penalties levied on both farmers and milk companies could help reduce these rates, making for a healthier system for both producers and consumers of milk.

Another strategy, which has worked elsewhere, would be forming a cooperative that would engage many farmers in jointly selling their milk.

“Because you have more farmers contributing, there is more accountability,” Redding says. “I would love to try to do an intervention like that in Cajamarca.”