- Lead was detected in 99 per cent of the 100 cat foods tested.
- Cadmium was found in 96 per cent and arsenic in 94 per cent of samples.
- Researchers stressed that detecting a contaminant does not establish that a particular food will harm a cat.
Nearly all of the cat foods tested in a new investigation contained detectable traces of heavy metals or other contaminants, including lead, arsenic, cadmium, pesticides and plastic chemicals.
The analysis, by US nonprofit Clean Label Project, reported by CNN, tested 100 top-selling cat foods from 62 brands for more than 122 contaminants. According to the investigation, lead was detected in 99 per cent of samples, cadmium in 96 per cent and arsenic in 94 per cent.
The findings covered wet, dry and air- or freeze-dried foods, as well as products marketed as natural or premium.
But the results need some context. The investigation measured the presence of contaminants; it did not establish that the levels detected would cause illness in cats. Clean Label Project itself says its testing does not determine whether a specific product will cause harm to an animal.
The organisation says its category studies use products bought at retail rather than samples supplied by manufacturers, with testing carried out by Ellipse Analytics, an ISO 17025-accredited laboratory.
Heavy metals found across different types of food
Molly Hamilton, executive director of Clean Label Project and an author of the report, said cats could be particularly relevant to concerns about repeated exposure because many eat the same food every day.
“Most cats eat the same foods nearly every day, with little variation,” Hamilton said.
“The contaminants are an ongoing exposure that may accumulate in cats’ bodies,” she added, noting that chronic kidney disease is one of the common causes of death in older cats and that the kidneys play an important role in filtering heavy metals.
The investigation found differences according to the type of food and protein used.
Dry cat food contained roughly three times as much lead as wet or air-dried products, according to the analysis.
Fish and seafood-based foods were more strongly associated with mercury and cadmium than products using other proteins. Mercury levels were about 18 times higher and cadmium levels about 2.5 times higher in fish- or seafood-based foods than in foods using other proteins.
Wet seafood products had the highest mercury levels, with the analysis finding nearly 28 times as much mercury as in wet foods made with other meats, particularly poultry.
That does not mean all fish-based cat food was high in mercury, Hamilton stressed.
“As the main protein, chicken was better when it came to mercury and cadmium, but we saw higher rates of lead and herbicides in chicken,” she said.
“It’s a whack-a-mole situation — which contaminant do you want to whack?”
Clean Label Project said about 85 per cent of poultry-based foods met its own purity standard, compared with 25.7 per cent of fish and seafood products.
Heavy metals occur naturally in soil, water and air, although industrial, agricultural and mining activity can increase contamination. They can consequently enter food through ingredients and environmental exposure.
The presence of a detectable amount, however, does not by itself establish a health risk.
The Pet Food Institute, which represents US pet food manufacturers, made that point in response to Clean Label Project's earlier dog-food investigation. It said modern laboratory methods can identify trace amounts of naturally occurring substances at levels that may be far below those associated with harm.
Glyphosate and plastic chemicals add to concerns
The investigation also looked beyond heavy metals.
Glyphosate, a widely used agricultural herbicide, was detected in 37 per cent of the products tested, according to Clean Label Project. The organisation said foods containing more plant ingredients among the first 10 listed ingredients tended to have higher detected levels.
Hamilton said cat foods with two plant ingredients among their first 10 ingredients had roughly 40 per cent more glyphosate than comparable foods with one, while products with five plant ingredients had nearly four times as much.
The health debate around glyphosate remains contested. The International Agency for Research on Cancer classified it as “probably carcinogenic to humans” in 2015, while the US Environmental Protection Agency has reached a different assessment.
The investigation also detected di(2-ethylhexyl) phthalate, or DEHP, a plasticiser used in PVC and some food-contact applications, in about half of the products tested.
Ryan Babadi, science director at Toxic Free Future, a nonprofit consumer product safety organisation, called the finding concerning and suggested that contamination could occur during food processing through contact with PVC tubing or other equipment.
“It was detected in about half of the products tested, with the highest levels in canned and pouch products,” Babadi said.
“It is encouraging to see those harmful bisphenols, including BPA, were found less frequently, suggesting pet food can be produced and packaged without these endocrine-disrupting chemicals,” he added.
The Pet Food Institute said manufacturers use food-safety and quality-assurance systems that include ingredient specifications, supplier verification, testing, traceability and preventive controls.
“Cat owners should feel confident that the food they feed their pets is safe and produced according to rigorous regulatory and quality standards,” said Elise Fennig, president and chief executive of the Pet Food Institute, as per the report.
The organisation has also argued that contaminant studies need to provide sufficient scientific and regulatory context, including information on sampling, analytical methods and established safety thresholds.
There are also limitations to the new investigation itself.
Each product was tested from a single batch, meaning the results cannot show how contamination might vary between different batches of the same food. The research also compares contamination across categories rather than establishing a safe or unsafe level for an individual cat.
Hamilton acknowledged that distinction.
“Every product in this study was purchased at retail, and no brand had any role in selecting products, conducting testing or analyzing the results. No brand saw the results before publication,” she reportedly said.
The organisation's own consumer guidance also notes that laboratory results need to be interpreted in the context of detection limits, testing methods and serving sizes.
For cat owners, that means the study does not provide a simple list of foods that are safe or unsafe.
Instead, it raises questions about how frequently pet-food manufacturers test for contaminants and how much information consumers receive about those tests.
Hamilton said owners concerned about a particular product should ask the manufacturer whether it carries out contaminant testing and how often.
“The best way to know what’s in your cat’s food is to contact the manufacturer and determine if they test the food – and how frequently they test,” she said, as per reports.
The findings therefore offer a reason for greater scrutiny of pet-food testing and supply chains, but they are not evidence that nearly all commercial cat food is dangerous.
For now, the clearest finding is narrower: contaminants that are not normally highlighted on the front of the packet were detectable in a large proportion of the products tested, and the investigation has renewed questions about how those levels should be measured, regulated and communicated to pet owners.
