The next burger you bite into may be more than you’ve bargained for.

Earlier this Tuesday, California-based upstart Clear Labs released another of its extensive food reports, this time specifically focusing on hamburgers. Using their own uniquely designed method of molecular analysis, the lab tested 258 samples of hamburger meat from 79 brands and 22 retailers. They found that 13.6 percent of the samples had noticeable quality flaws ranging from contamination to missing ingredients. These issues were only amplified in veggie brands, with 23.6 percent of the 89 vegetarian products tested revealing problems, including two samples containing trace amounts of beef DNA.

“Vegetarian products may not be perceived as a traditional food safety risk, but our findings suggest that vegetarian products are problematic from both a safety and quality perspective,” stated the report.

Hamburger Flaws

The lab found three broad problems in the burger samples: substituted or missing ingredients, contamination, and inaccurate nutritional information.

Sixteen products, or 6.6 percent of the samples, had ingredients like beef, pork and chicken that weren’t supposed to be there. Two products had added rye grain, while one contained artichoke. Fourteen samples, all vegetarian, had missing ingredients — in one particularly egregious example, a black bean burger product contained zero black bean. While these mistakes may seem innocuous enough, the report notes that many people actively avoid ingredients like pork and rye for religious and health reasons.

On the grosser end of the scale, about 1.6 percent had hygienic issues. Human DNA was found in one frozen burger product, while rat DNA was found in three. Germ contamination was higher, though still relatively small, at 4.3 percent. Some of the pathogens detected included E.coli, Yersinia enterocolitica, and Clostridium perfrigens.

Alarming as these discoveries might seem, both the report and outside experts note that there’s probably not too much to worry about. In the case of the human and rat DNA, it’s doubtful they represent any harm to customers, and they likely fall within the acceptable range of contamination established by regulatory agencies like the Food and Drug Administration (FDA). And according to Dr. Michael Doyle, director of the Center for Food Safety at the University of Georgia, the presence of these specific germs may not mean anything, in part because it’s impossible to tell whether they were even alive at the time of the testing.

“Finding the DNA of Salmonella or E.coli from a dead cell is not very helpful,” Doyle told the Genetic Experts News Service. “Secondly, the pathogens they find, such as Yersinia enterocolitica and Aeromonas hydrophila, are not of common concern in foods. In terms of Clostridium perfrigens, you usually need to have millions of cells in the food in order to cause illness. And it’s not uncommon to find low levels in meats, which contain some C. perfringens naturally.”

Of all the issues the lab detected, the most relevant one likely has to do with the nutrition we’re actually getting from our burgers. Forty-six percent of the samples contained more calories than advertised, with an average of 39.6 more calories per serving. Forty-nine percent of the samples also had more carbohydrates. And while fast food burgers had the lowest rate of other quality issues, they overwhelmingly undercounted their nutritional figures. Thirty-eight of the 47 fast food products tested had more calories than labeled, with 12 products containing at least 100 more calories per serving.

“Considering that FDA labeling requirements make it mandatory for most fast food restaurants to publish nutritional information on fast food menus, these discrepancies are potentially worrisome for customers who make decisions about what to order based on calorie counts and other available nutritional information,” stated the report.

Conceived as a guide for hamburger producers, the report authors believe their findings can push the industry to improve itself, specifically in establishing a clearer standard of consistency. “While several subsets of the industry have championed food safety, others such as vegetarian products have fallen behind,” the report concluded. “Similarly, end-product consistency continues to disparage public perception of the burger industry.”

And while these findings will have to be verified by other independent scientists, Doyle does believe the methods pioneered by Clear Labs have a clear role in the future of food safety. "Overall, I think this technology is going to be of great benefit with regard to detecting purposeful adulteration of foods or indicating the presence of ingredients not on the label that may impact human health such as allergens,” he said.