In his 2011 Petfood Industry column, “PCB and dioxin: side effects of our industrialized world,” polychlorinated biphenyls (PCBs) and dioxins were identified as a recurring, low-frequency/high-impact threat, by Greg Aldrich, Ph.D., Kansas State University research associate professor and Nulo Pet Food chief operating officer. Polychlorinated biphenyls (PCBs) and dioxins are mostly man-made, environmentally persistent compounds that bioaccumulate in fat, move up food chains, and occasionally enter the feed and food system through mishandling, industrial incidents or contaminated raw materials.
While there haven’t been any class action lawsuits related to these compounds to date, legal problems for pet food companies have arisen from BPA, heavy metals and other compounds that may unintentionally occur in pet food. For example, in January, class action lawsuit involves the use of per- and polyfluoroalkyl substances (PFAS) on pet food packaging has moved closer to certification. The on pet food packages and the alleged health effects on pets from those compounds, often referred to as “forever chemicals” because of their longevity both in and out of living bodies. In 2024, the U.S. Food and Drug Administration announced that grease-proofing materials containing certain per- and polyfluoroalkyl substances (PFAS) are no longer being sold for use in food packaging in the U.S., including pet food bags.
Like PFAS, dioxin and PCBs bioaccumulate in the bodies of pets and people. The practical pet food concern remains in fat-rich animal and marine inputs (e.g., rendered fats, fish meal/oil, marine by-products). The U.S. regulatory language itself highlights this risk pathway by setting a higher PCB tolerance for animal-origin feed components including fishmeal and other marine by-products, according to Cornell Law School’ Legal Information Institute.
In 2011, Aldrich cited U.S. “temporary tolerances” for PCBs. Currently, 21 CFR § 509.30 - Temporary tolerances for polychlorinated biphenyls (PCB's) still states:
- 0.2 ppm in finished animal feed for food-producing animals (with specified exceptions),
- 2 ppm in animal-origin feed components (including fishmeal/marine by-products) and in certain finished feed concentrates/supplements/premixes for food-producing animals,
- 10 ppm in paper food-packaging material intended for or used with finished animal feed/components, with a functional barrier exception.
Thankfully, pet food does not include feed for “food-producing animals.” Nevertheless, this regulation is still commonly cited in U.S. feed quality discussions because it sets federal tolerance concepts and analytical compliance expectations. The pet food–specific regulatory posture could be described as control via ingredient approval/CGMPs, supplier controls and enforcement actions, rather than a single pet-food-only PCB limit.
Since 2011, the most consequential shift is the tightening health-based guidance in Europe. European Food Safety Authority’s 2018 risk assessment established a tolerable weekly intake (TWI) of 2 pg WHO2005-TEQ/kg body weight/week for the sum of dioxins and dioxin-like PCBs, a figure reiterated in EFSA materials summarizing the 2018 opinion. This does not directly set pet-food legal limits, but it suggests a stricter consideration of chronic-exposure that may influence monitoring expectations across food/feed systems.
Aldrich described PCBs largely as legacy industrial chemicals. Today’s scientific literature adds that some PCBs are still formed unintentionally during certain manufacturing (notably pigments and related processes), with PCB-11 frequently discussed as a marker congener in this context, according to research published in the journal Atmospheric Pollution Research.
For pet food, the practical takeaway from current Food and Drug Administration documents is that contamination risk management should include food observation of contact materials and printed/recycled paper streams, alongside ingredient monitoring, especially where functional barriers are absent.
