Some pet foods contain potentially harmful PFAS chemicals
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Many pet foods – especially those based on fish – have levels of so-called persistent chemicals that exceed the European Health Agency’s thresholds for humans.
The findings point to an urgent need for increased monitoring of contaminants in pet products and a better understanding of risks for companion animals, says Kei Nomiyama of Ehime University in Japan.
“Our findings do not indicate an immediate health situation, but they highlight a knowledge gap,” he says. “Pet owners who wish to reduce potential exposure may consider paying attention to ingredient composition and diversifying protein sources.”
Perfluoroalkyl and polyfluoroalkyl substances (PFAS) are man-made chemicals used in a wide range of products, which can persist in the environment for hundreds or thousands of years. People who experience regular exposure to PFAS have an increased risk of liver damage, certain cancers and other health problems. While research on their effects on pets remains limited, studies on cats have linked certain PFASs to liver, thyroid, kidney and respiratory diseases.
Nomiyama and his colleagues had already found persistent organic pollutants in pet food. Since PFAS are only slightly present globally – especially in rivers and oceans – they suspected that they would also find traces of these pollutants.
To find out, they measured concentrations of 34 types of PFAS in popular varieties of wet and dry pet food—48 for dogs and 52 for cats—marketed in Japan between 2018 and 2020. Then, using approximate meal sizes and body weights for dogs and cats, the team calculated how much PFAS per day a pet would ingest per day.
Several of the products had moderate to high levels of PFAS – often above the daily intake limits (per kilogram of body weight) set for humans by the European Food Safety Agency (EFSA).
Among dog foods, some of the highest levels appeared in Japanese grain-based products — possibly due to agricultural runoff or fish by-products as protein sources, Nomiyama says. In contrast, meat-based products were generally low in PFAS, with one Japanese and two Australian brands containing none.
As for the cat food, fish-based products from Asia, the US and Europe had the highest PFAS levels, particularly a fish-based wet food made in Thailand.
“The ocean often acts as a final sink for many synthetic chemicals,” says Nomiyama. “Simply put, PFAS can move through and concentrate in aquatic food webs.”
Regional differences may reflect historical and current patterns for the production and use of PFAS, as well as differences in raw material procurement, he says. Nevertheless, PFAS contamination is a global problem. “More globally harmonized monitoring would be valuable,” he says.
EFSA declined to comment on the study’s findings, but said its proposed intake limits for humans should not be applied as such to the risk assessment of other animals.
Nomiyama agrees – but emphasizes that the findings nevertheless reflect abnormally high levels of PFAS, and that risk assessments for pets deserve development.
“Pets share our environment and act in many ways as sentinels for chemical exposure,” he says. “Understanding contaminant levels in pet food is not only a matter of animal health, but also contributes to our broader understanding of environmental contamination pathways. Long-term exposure and species-specific toxicity assessments in companion animals deserve further attention.”
Håkon Austad Langberg at Akvaplan-niva, a Norwegian non-profit research institute, says the findings come as no surprise. “These substances are globally distributed, and several PFASs are known to persist and, in some cases, accumulate and/or magnify through food webs,” he says.
“The bigger problem is that PFAS are everywhere, and both humans and animals are exposed from multiple sources,” says Langberg. “These compounds are found across environmental media and in a variety of products, resulting in cumulative exposure to both humans and animals. The study contributes valuable data to the broader challenge.”
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