Testing found lead in 99% of cat foods examined, with cadmium and arsenic also widespread.
Fish-based foods had significantly higher mercury levels, while dry foods contained more lead.
Reading ingredient labels and asking brands about their testing practices may help cat owners make more informed choices.
Choosing cat food can be overwhelming, especially when premium prices and natural-sounding labels make certain products seem like healthier options. But a new report from the Clean Label Project raises questions about what else might be in the food cats eat every day.
The organization tested 100 cat food products for more than 122 environmental contaminants and toxins. The results found heavy metals in nearly all the products examined, although the levels varied considerably.
That matters because cats often eat the same food every day for years. According to the report, repeated exposure to contaminants could create ongoing concerns over a cat’s lifetime. The findings also suggest that paying more or choosing a product with an appealing ingredient list doesn't necessarily mean it contains fewer contaminants.
How the cat food study was conducted
Clean Label Project purchased 100 products from 62 brands, including 31 dry foods, 40 wet foods sold in cans or pouches, and 29 air-dried or freeze-dried products.
An independent laboratory tested the samples for a range of substances, including four heavy metals: arsenic, cadmium, lead, and mercury. Researchers also examined chemicals associated with packaging, herbicide residues, and substances that can form during food processing.
The team used specialized laboratory methods to measure the contaminants and reviewed the ingredient lists to look for relationships between ingredients and test results.
To compare products fairly, the researchers adjusted contaminant measurements for calories rather than simply comparing equal weights of food. Wet food contains considerably more water than dry food, so comparing equal weights could make wet products appear cleaner simply because they are more diluted.
What the results mean for cat owners
Lead was detected in 99% of the products, while cadmium appeared in 96% and arsenic in 94%.
Fish and seafood products stood out for mercury and cadmium: they contained about 18 times as much as other products, even after accounting for whether the food was wet or dry, and also had approximately 2.5 times as much cadmium.
Dry food, meanwhile, contained roughly three times as much lead as wet or air-dried food. Researchers also found that products with more plant ingredients tended to have higher levels of the herbicide glyphosate.
Still, the results don't mean every product carries the same level of risk or that cat owners should eliminate fish from their pets' diets. Some fish-based foods performed well, and the study reflects the products and samples tested rather than every batch on store shelves.
For consumers, the report recommends looking beyond the first ingredient on the label, considering different protein sources, and asking manufacturers whether they regularly test finished products for heavy metals. A single test represents only one batch, so ongoing quality controls matter, too.
The findings offer a reason to ask more questions about pet food quality, rather than assuming that a premium price or an appealing label guarantees a cleaner product.