You may have heard about industrial chemicals like bisphenol A, or BPA, making their way into our food supply via can linings--but what about our pets? Not surprisingly, they are vulnerable, too. Canned foods are a source of potential hazards. In fact, a recent study found that the amount of BPA in pet dogs’ bodies nearly tripled when they switched from bagged dog food to canned dog food (Koestel 2016).

At the Ecology Center, we pioneered a rapid method for identifying the types of polymer coatings used in food cans. The report that resulted, published in 2016, helped spur major food manufacturers Campbell’s and Del Monte to commit to phasing out BPA from all their cans. Now, we have completed a smaller study of pet food cans.  

The insides of food cans are coated with a polymer layer to protect the metal can from corrosion. These coatings, or linings, can leach chemicals into the food inside. BPA, a building block of certain polymers, is a well-known example of a chemical that migrates from the most common can coating, BPA-based epoxy. PVC-based can linings have also been shown to leach BPA derivatives called BADGEs into food (Alabi 2014, Hammarling 2000). BADGE compounds are hormone disruptors (Hyoung 2007).

In the recent study noted above (Koestel 2016), fourteen dogs who normally ate bagged food were fed canned food for two weeks. Not only did their BPA blood levels increase by nearly a factor of three, the dogs’ microbiota underwent changes that may impact metabolism.

BPA, long known to interact with human hormone receptors due to its similarity to estrogen, has been linked to surprising possible health effects in humans. These include obesity, diabetes, high blood pressure, and cancer. (Seachrist 2015, Rochester 2013.) Very little toxicological data exists regarding the chemicals that leach from PVC-based coatings, but evidence suggests they, too, are hormone disruptors (Hammarling 2000).

In fact, scientists have been warning for years that our pets can serve as unwitting sentinels of chemical contamination. A 2008 study from Environmental Working Group, for example, found the urine and blood of pet dogs and cats in Virginia contained 48 of 70 chemicals included in the screening. Levels of flame retardants, fluorochemicals, and mercury were often higher than found in people. 

For this study, we took a “citizen science” approach, asking community members to send in empty cat and dog food cans they had recently purchased for their pets. We received a total of 60 cans from pet owners in Southeast Michigan.  Using Fourier transform infrared (FTIR) spectroscopy, we identified the polymer type of the can linings of the interior body and lid of each can.  See Methods.

 

References

Alabi, et al, 2014. Quick and simple sample treatment for multiresidue analysis of bisphenols, bisphenol diglycidyl ethers and their derivatives in canned food prior to liquid chromatography and fluorescence detection. J Chromatogr A. 1336, 23-33.

Environmental Working Group, 2008. Polluted Pets.

Hammarling, et al, 2000. Migration of bisphenol-A diglycidyl ether (BADGE) and its reaction products in canned foods.  Food Addit Contam. 17(11), 937-43.

Hyoung, 2007. Developmental toxicity by exposure to bisphenol A diglycidyl ether during gestation and lactation period in Sprague-Dawley male rats. J Prev Med Public Health 40(2), 155-61.

Koestel, et al, 2017. Bisphenol A (BPA) in the serum of pet dogs following short-term consumption of canned dog food and potential health consequences of exposure to BPA. Science of the Total Environment 579, 1804-1814.

Rochester, 2013.  Bisphenol A and human health: a review of the literature.  Reproductive Toxicology, 42, 132-55.

Seachrist, et al, 2015. A review of the carcinogenic potential of bisphenol A.  Reproductive Toxicology 59, 167-82.

         
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