As part of an ongoing investigation into chemicals in our food supply, scientists found extremely high concentrations of a flame-retardant compound in a supermarket sample of brand-name butter.
It is the first documented case of serious contamination in food in the United States with a class of chemicals known as PBDEs, or polybrominated diphenyl ethers.
Commonly used in furniture and electronics, among other products, PBDEs are known to disrupt hormone function and have been associated with a range of health concerns, including cancer as well as reproductive, developmental, and neurological problems.
Since no federal agencies currently track levels of chemicals like these in food, there is no way to know how widespread this kind of chemical contamination is in butter or other products. But it clearly happens at least sometimes.
"This study and others mean that we are getting episodic contamination with persistent organic man-made chemicals, and that every so often, the level is much higher than the day-by-day ordinary levels," said Arnold Schecter, a public health physician at the University of Texas School of Public Health in Dallas. His group recently found traces of the hormone-disrupting chemical BPA in a wide range of canned foods.
Even though the Senate just approved a sweeping new food safety bill that would give the U.S. Food and Drug Administration more power to prevent people from eating tainted food, Schecter added, the bill focuses only on bacteria, not chemicals.
"I would feel much more comfortable with the food we're all eating if I knew the federal government was trying to do large, systematic and periodic sampling to figure out which contaminants are getting in, what their route is, and how we can decrease their amounts," he said. "From what I've read, there does not seem to be any consideration for chemical contamination in the new bill, which is very unfortunate."
For years, Schecter and colleagues have been measuring levels of hormone-disrupting chemicals in both our bodies and our food. As the researchers looked through some of their data recently, they noticed high levels of one type of PBDE flame-retardant in a pooled sample of 10 kinds of butter.
To follow up, the researchers went back to the original 10 butter samples, which they had collected over a few months from Dallas grocery stores. After testing each type of butter separately, results showed that nine of them contained low levels of PBDEs, consistent with what previous studies have found in various foods. (PBDEs often enter the food supply as dust that gets in through soil, water and air).
But compared to those untainted samples, one pat of butter contained more than 135 times more of a PBDE called deca-BDE, the scientists report today in the journal Environmental Health Perspectives. Levels of that chemical in the butter's wrapper were even higher, Schecter said, suggesting that contamination came from the packaging.
"We had never seen or read anywhere about PBDE-contamination of food at such high levels," he said. "We were really startled. This is entirely new to us."
After talking with representatives from the company that made the butter, Schecter suspects that an electrical incident was to blame. If there was a fire or overheating in machines that contain PBDE flame-retardants, the chemicals could have ended up in the paper and later migrated into the butter.
Schecter wouldn't name the manufacturer, but he hinted that its headquarters are located near the Minneapolis-St. Paul metro area and he said that the company had recently advertised that it was using new and improved wrappers for its butter.
Another sample of the company's butter was tested in this study, but that one did not show the same high levels of contamination.
"We don't know whether this was a one-in-a-million occurrence, or whether there was some kind of processing or electrical incident that maybe government agencies could track down and figure out how the chemicals got in there," Schecter said.
Chances are, said Mike McClean, an environmental health researcher at the Boston University School of Public Health, the new study did not find the only sample of contaminated butter out there.
"Think of all the butter in the United States, and if in just 10 samples, you find one, that is super-high," McClean said. "I don't think they stumbled upon an isolated incident. I personally think you could go take 10 samples of lots of different types of foods and probably find something similar."
Rather than make consumers wary of grocery shopping, McClean added, the findings point to the need for regulators to work on preventing and detecting chemicals in our food in the first place.
"We basically have all of these chemicals in our bodies just from being in an indoor environment and from eating," he said. "You're certainly not going to be able to control that by being careful about what kind of butter you buy."