You have no way of knowing where the meat in most hamburgers really comes from

US Department of Agriculture/Flickr

If you buy hamburger meat to grill for the holiday weekend, take a look at the label. You may be surprised at what it doesn't tell you.

There's no way for a consumer to know where the meat in their hamburger comes from. 

It's not just that the information isn't printed on the label. Very few producers grind meat from individual cows — it's just too expensive. And at least for the foreseeable future, there's no test scientists can run that can backtrace meat once it's been ground.

Scientists can determine where an individual piece of meat comes from using a technique called isotope analysis, looking at the specific fingerprints of carbon, hydrogen, and nitrogen atoms to see where a cow lived.

"But that has to be pure, it cannot be burger," Mansour Samadpour, a scientist at IEH Laboratories who tests food products including hamburger meat, told Tech Insider.

And a hamburger isn't just a mix of meat from a couple of cows who shared the same field.

Chances are good that the meat in your hamburger comes at least from a couple of different slaughterhouses across the US, if not from different countries.

US Department of Agriculture/FlickrThat's because hamburger makers target their mixes to hit specific ratios of lean and fatty meat. Individual cows don't usually come in the ratios consumers want to buy, like 80% lean meat.

"The hamburger maker is looking for a precise amount of fat content," Michael Moss, a journalist who wrote a Pulitzer Prize–winning piece on the meat industry, told Tech Insider. "They're throwing pieces of meat in the grinding machine and keeping very careful track of the percentage of fat."

In order to balance lean and fatty cuts and try to source the cheapest meat, hamburger makers don't just rely on a network of American slaughterhouses, Mansour adds. They also use imported meat, particularly from Australia, New Zealand, and Uruguay.

But US Department of Agriculture rules don't require hamburger producers to tell customers where the meat in any individual package may have come from. And many brands avoid explaining how they source their meat, although some do choose to do so.

The National Cattlemen's Beef Association, the main beef industry group in the US, "supports voluntary labeling efforts that are industry led and consumer driven," spokesperson Chase Adams told Tech Insider in an email.

Adams also pointed Tech Insider to a blog post from the industry group Beef Checkoff, which confirms that the meat in one hamburger can come from many different sources. The post notes that regulators have the same quality standards for domestic and imported meat, so "the number of cows whose lean trim is used doesn't represent the safety of your food."

Beyond safety, there are other reasons why consumers might want to know where their burger comes from, like supporting the American economy or reducing carbon emissions from shipping goods long distances.

But without labeling, they're out of luck. "It leaves consumers absolutely in the dark about the sourcing of the meat in a hamburger," Moss said.

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