Would you eat a burger with human genetic material in it?

A new study of burger products finds that while the beef industry overall is well-regulated and has benefited from stringent testing, the patty that winds up in your bun is not always all it claims to be.

In a few products, human or rat DNA was found.

Clear Labs analyzed 258 samples ? including ground meat, frozen patties, fast food burgers and veggie burgers ? from 79 brands and 22 retailers. None of the manufacturers or retailers was identified.

The researchers found that 13.6 percent of the samples contained something they shouldn't or were missing something they should have had.

In some cases, other meats like pork were substituted for ground beef. Obviously that can be a problem for Jews, Muslims and followers of other religions that eschew consumption of pig products.

Rye, a cheap filler with a high gluten content, was found in samples of frozen chicken sliders and a veggie burger. Sunchoke (Jerusalem artichoke), which contains the carbohydrate inulin, known to cause gas and bloating, showed up in a frozen burger patty.

All of the 14 samples missing ingredients they were supposed to contain according to their labeling were vegetarian products.

The worst offender was a black bean vegetarian burger that was missing any trace of black beans.

The scientists discovered human DNA in a veggie burger. Rat DNA was detected in three samples, one each in a fast food burger, a vegetarian burger and ground meat. Clear Labs said that contamination probably fell within accepted regulatory range.

A total of 4.3% of all products tested positive for pathogenic DNA, and more than a quarter of those items were vegetarian products. The presence of pathogenic DNA in vegetarian products is especially alarming, because pathogens found in meat and fast food burgers that have been precooked are less likely to be alive.

The North American Meat Institute was unimpressed with Clear Labs' findings.

"A review of the company's procedures suggest collection methods prone to mistakes and a range of errors throughout the analysis process, said institute vice president Betsy Booren. "A look at the company's own promotional video featuring shots of overpacked freezers and technicians testing products using plastic forks and knives with paper towels would suggest cross contamination in the lab is a very good possibility.