Study Finds Rat DNA in Beef Patties, No Black Beans in Black Bean Burgers

As 21st-century humans, we regularly shovel all kinds of food into our greedy faces without any clue about its provenance. It's crazy, if you think about it—the burger you are about to bite into had quite the journey before it landed in your hands. And along that journey, it's anyone's guess as to where that meat has been.

While we've all been eating burgers in ignorant bliss, a new report suggests that mystery meat really lives up to its name. San Francisco-based Clear Labs recently published a survey studying the ingredients in a variety of kinds of burgers purchased in Northern California, and found some unpleasant surprises, like rat DNA in patties of all kinds and meat in veggie burgers. Yum!

Clear Labs took a look at 258 burgers purchased at stores and fast food restaurants, looking at ground meat, frozen patties, and veggie burgers from 79 brands and 22 retailers. After analyzing the burgers, they found all kinds of problems with unexpected ingredients and contamination. In addition to two cases of meat in supposedly vegetarian burgers and three cases of rat DNA various patties, they found that 4.3 percent of products had pathogenic DNA, one black bean burger contained no black beans, and one burger even contained human DNA.

That might not be as bad as it sounds. Clear Labs notes that while the presence of human and rat DNA might be unpleasant, it probably isn't harmful. The rat DNA—found in one fast food burger, one vegetarian burger, and one sample of ground meat—likely came from rat feces, and the human DNA from hair. Both, Clear Labs notes, may fall within an acceptable regulatory range.

And those who try to skirt any sort of contamination by going the vegetarian route are in for an even more unwelcome surprise. Nearly a quarter of veggie burgers didn't contain the ingredients that their labels claimed, compared to just under 14 percent of all burgers sampled. It wasn't just veggie burgers that fudged their ingredients, though—one beef burger contained pork, another bison, and yet another chicken. One sample of ground lamb contained beef.

The report notes that this type of contamination could be problematic for people who follow certain diets for religious reasons, like avoiding pork in accordance with halal or kosher restrictions.

But overall, 4 percent of burgers tested contained pathogens that could cause foodborne illness. Out of those 11 burgers, four were vegetarian.

Clear Labs works with food companies to help them clean up their supply chains, so hopefully contamination issues improve in the future. But who knows—maybe we like the taste of rat DNA.