June 1, 2012
Dangerous Fat-Soluble Chemical Being Found In Meat, Peanut Butter and Fish
A common flame retardant chemical is showing up in a variety of store-bought foods including meat, peanut butter and fish. The discovery of the chemical HBCD adds to growing evidence that our food supply is full of unwanted chemicals, including flame retardants.
The study also draws yet more attention to growing concerns about a ubiquitous class of poorly regulated chemicals that, according to growing evidence, may be harmful to our health, the environment and wildlife. Despite all the potential risks, flame retardants are also possibly ineffective at resisting fires in many situations.
"What we're seeing are chemicals that can cause endocrine disruption, that can cause nervous system damage, that can cause reproductive damage, that can cause developmental damage, that can cause cancer in some cases," said Arnold Schecter, a public health physician at the University of Texas School of Public Health in Dallas, who has been systematically uncovering a wide range of chemicals in supermarket foods. "To me, what I see as the big picture is the fact that, now that we're looking, we’re finding them in many of the foods we're looking at -- not all of them, but in large numbers of them."
HBCDs are a group of brominated flame retardants that appear frequently in home insulation materials. They are more common in Europe than in the U.S. or Canada but in previous work, Schecter found the chemical in the breast milk of American women as well as in various foods sold here.
A study found that pregnant women in Northern California have the highest flame retardant exposures reported to date among pregnant women worldwide. It also describes some of the first evidence from humans that certain flame retardants may interfere with thyroid hormone signaling during pregnancy, which is critical to fetal brain development.
Evidence that a substance is persistent and bioaccumulative, when considered with the potential for environmental release and the potential for toxicity to organisms, provides an indication that the substance may enter the environment under conditions that may have harmful long-term ecological effects.
Release of HBCD into the environment may occur during manufacture, processing, transportation, use, improper handling, improper storage or containment, product usage and disposal of the substance or products containing the substance.
There are dozens of chemicals that manufacturers use to try to reduce the flammability of all sorts of products, including furniture, electronics, baby car seats and carpets. Based on their chemical structures, flame retardants can fit into one of several categories, and some categories have raised more health concerns than others.
So far, two classes of flame retardants -- brominated and chlorinated -- have sparked the most worry, Schecter said, partly because they accumulate in human tissues and partly because they last for a really long time. After exposure, the human body can take up to 219 days to break down just half of a dose of some of the most persistent versions.
Recent studies suggest that we are constantly exposed to a variety of flame-retardants. House dust is full of the chemicals, which easily leach out of treated foam in furniture and other household objects. Studies have found these chemicals in animals as well as in human blood, urine and breast milk. One group of flame retardants called PBDEs, which are commonly used in the United States, appear in breast milk at higher levels in America than they do in Europe, where PBDEs are being phased out.
UC Riverside scientists have done research using rat tissue that shows that PBDEs disrupt mechanisms that are responsible for releasing hormones in the body. Moreover, their work has shown that like polychlorinated biphenyls (PCBs), whose manufacture in the U.S. was discontinued in 1977, PBDEs alter calcium signaling in the brain -- a critical mechanism for transmitting information between and within brain cells, for learning and memory, and for regulating the release of hormones in the body.
PBDEs mobilize into the indoor air and household dust from household goods, resulting in humans and pets getting exposed continuously to these toxicants. Over time, PBDEs, PCBs and similar organic toxicants leach into the environment when household wastes decompose in landfills or are incompletely incinerated. They are now found in air, water and soil as well as in wildlife and supermarket foods. When people ingest food contaminated with PBDEs, it adds to their body burden over their lifetime.
To get a more detailed picture of which forms of HBCDs show up most often in our food supply and which foods carry the highest loads, he and colleagues bought 36 types of food from Dallas supermarkets. They picked foods that had tested positive in their previous work, including fish, turkey, peanut butter, bacon, and beef. The list was heavy on fat-containing foods because HBCDs are fat-soluble.
In the new study, levels turned out to be highest in canned sardines, fresh salmon, peanut butter and tilapia, the researchers report today in the journal Environmental Health Perspectives. Other foods that tested positive at lower amounts included canned chili and sliced ham, turkey, chicken and other deli meats.
Individually, none of the foods had high enough levels of HBCDs to be of concern. But that doesn’t necessarily mean there’s nothing to worry about.
"The levels are lower than levels that any government agency that we know of has suggested as a do-not-exceed or dangerous or reference dose -- that’s the good news," Schecter said. "The thing that isn't good news is that we are finding so many different toxic chemicals in food."
"What concerns me is that the limits that are recommended not to be exceeded that government agencies put out are usually reviewed one at a time from animal studies or cell culture studies or human epidemiological studies," he added. "I don't think we have a good feel for what the toxicity is of these mixtures of chemicals found in our food and in our bodies."
The new findings are useful, considering we know relatively little about HBCDs, said Heather Stapleton, an environmental chemist at Duke University in Durham, N.C.
It's impossible to completely avoid flame retardants, she said. But to reduce chemical exposures, she recommended frequent hand-washing. She also suggested that consumers call manufacturers and ask them to provide more information about what chemicals they use in their products.
"We know these accumulate in house dust, and now it seems another route of exposure is in food," Stapleton said. "There's just so much we don't know."
April McCarthy is a community journalist playing an active role reporting and analyzing world events to advance our health and eco-friendly initiatives.