Cat food investigation finds heavy metals, pesticides and plastic chemicals

By Sandee LaMotte, CNN

(CNN) — Nearly all tested cat foods contain toxic plastic contaminants, the herbicide glyphosate and heavy metals such as lead, mercury and arsenic, according to a new investigation provided exclusively to CNN.

“Most cats eat the same foods nearly every day, with little variation,” said report author Molly Hamilton, executive director of the Clean Label Project, a Colorado nonprofit that tests consumer products for contaminants and certifies those meeting its standards.

“The contaminants are an ongoing exposure that may accumulate in cats’ bodies over their lifetimes,” Hamilton said. “For example, chronic kidney disease is among the most common causes of death in older cats — the kidneys play a major role in filtering heavy metals.”

Toxins were found in all types of cat food — wet, dry and air- or freeze-dried — even in products labeled as natural and nutritionally superior, according to the analysis released Friday.

“Cat owners increasingly choose premium meats, organic vegetables and cleaner labels, assuming higher prices and quality ingredients mean healthier food,” Hamilton told CNN. “That’s not necessarily the case.”

Clean Label published a similar assessment of dog food in February that found three to 13 times more heavy metals than human food. Lead and cadmium exposure has been linked to canine cancer, a leading cause of death in dogs.

Heavy metals occur naturally in soil, water and air, but agricultural, industrial and mining pollution can increase and spread contamination. Plastics and other contaminants may also enter food during manufacturing, the report said.

“Overall, this appears to be a reasonably conducted analysis,” said Ryan Babadi, science director for Toxic Free Future, a nonprofit consumer product safety organization.

“Major retailers have the responsibility to require their suppliers to eliminate harmful chemicals from pet food and packaging — chemicals that are already being phased out or banned in many other products,” said Babadi, who was not involved in the investigation.

The Pet Food Institute, which represents manufacturers of cat foods, told CNN in an email that pet food manufacturers do implement comprehensive food safety and quality assurance programs.

Those include “ingredient specifications, supplier verification, testing protocols, traceability systems, and science-based preventive controls designed to ensure products are safe, nutritious, and consistent,” said Elise Fennig, the CEO for the Pet Food Institute.

“Cat owners should feel confident that the food they feed their pets is safe and produced according to rigorous regulatory and quality standards.”

Lead found in 99% of all samples

The investigation tested 100 top-selling cat foods for more than 122 contaminants, including lead, arsenic, cadmium, mercury, pesticides, herbicides and phthalates, the plastic chemicals linked to an increased risk of death in humans.

Lead was found in 99%, cadmium in 96% and arsenic in 94% of cat food samples across 62 brands. Contamination varied by product type — wet, dry, and air- or freeze-dried — and the type of protein, such as poultry, beef or fish.

Cadmium is classified as a human carcinogen and harms the kidneys and bones. A buildup of lead in the body damages nearly every major organ system. Inorganic arsenic — the type found in soil and water — is also a known human carcinogen.

Dry cat food contained roughly three times more lead than wet or air-dried products. No level of lead is safe for people, and children are most vulnerable: Their bodies absorb up to 50% of ingested lead, compared with about 10% for adults, which can cause stunted growth, decreased IQ, hyperactivity and irritability.

Cats and other small pets also absorb more than larger ones, yet few regulations control contaminants in pet food, Hamilton said. “The absence of safety standards does not mean a contaminant is safe. Most guidelines are designed for farm animals, not kittens or 15-year-old housecats.”

Fish and seafood — popular proteins for cats — had the strongest association with mercury and cadmium, the report found. Because microorganisms in water turn regular mercury into methylmercury, a toxic chemical form that binds tightly to fish tissue, the heavy metal accumulates to higher levels in aquatic animals.

Mercury is toxic to the nervous, digestive and immune systems, as well as the kidneys, lungs and skin, according to the World Health Organization.

Mercury levels were about 18 times higher and cadmium levels about 2.5 times higher in fish- or seafood-based cat foods than in foods made with other proteins. Wet versions of seafood products contained the most mercury — nearly 28 times as much as wet foods made with other meats, especially poultry.

“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,” Hamilton said. “It’s a whack-a-mole situation — which contaminant do you want to whack?

“That doesn’t mean all fish options were high in mercury — levels depend on manufacturers’ quality-control testing,” she added. “We certified several fish-based foods.”

Nearly 85% of poultry-based foods met Clean Label Project’s purity standard compared with 25.7% of fish and seafood products.

“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,” Hamilton said.

Glyphosate and phthalates

Although cats are carnivores, many manufacturers add produce to cat food for its antioxidants, minerals and vitamins. Unless grown organically, those plants may be exposed to pesticides. A national report found the vast majority of 100 popular fruits and vegetables tested positive for a wide variety of bug-killers.

The Clean Label investigation tested for glyphosate, which is agriculture’s most widely used herbicide. Glyphosate was found at detectable levels in 37% of products, and cat food with more plants in the first 10 ingredients had higher glyphosate levels.

The WHO’s International Agency for Research on Cancer classified glyphosate in 2015 as “probably carcinogenic to humans.” The US Environmental Protection Agency disagrees.

“On average, cat food with two plant ingredients among the top 10 on the label had roughly 40% more glyphosate than a similar food with one plant ingredient. Cat food with five plant ingredients had nearly four times as much,” Hamilton said.

Another “very concerning finding” was the widespread presence of di(2-ethylhexyl) phthalate, or DEHP, a chemical used in PVC plastics and some food-contact materials that is linked to cancer, birth defects and other health concerns, Babadi said.

“It was detected in about half of the products tested, with the highest levels in canned and pouch products. DEHP contamination could potentially occur during food processing, including through contact with PVC tubing or other farm or food processing equipment,” he 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,” Badadi added.

The research did have limitations. Each product was tested from a single batch. Therefore the study could not capture differences that might occur between batches of the same product.

“Brands that routinely screen for contaminants of concern tend to have more consistent results over time,” Hamilton said. “In addition, this study compares contaminant levels across products in each category of wet, dry and air- or freeze-dried. It does not determine whether a specific product will cause harm to a cat.”

What pet owners can do

If your cat favors seafood, vary its diet with chicken or other proteins to limit daily exposure to mercury and cadmium. Read the ingredient list carefully, however, as cat foods without fish in their name may still contain seafood ingredients and thus higher levels of mercury and cadmium.

According to the Clean Label report, wet or air-dried products are preferable to dry food for lower lead exposure, while avoiding foods with plants in the top 10 ingredients may lower pesticide exposure.

In addition, don’t rely on the first listed ingredient to gauge toxins. In more than a third of tested products, it didn’t tell the full story, Hamilton said.

“The first ingredient on a food label is often the biggest selling point because ingredients are listed by weight,” she said. “We tested and found the first ingredient is not always a reliable indicator of what the food contains, nor does it predict which contaminant may be present at the highest levels.”

One reason: Manufacturers need not disclose which part of a fish or other protein they use, Hamilton said. Wild salmon, for example, may sound healthier, but its liver, kidneys, intestines, head and skin store more chemical pollutants than the rest of the fish.

“Yet you have no idea what part of the fish is in that cat food,” Hamilton said. “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.

“Because even if they were to tell you what part of the fish that they’re using, without testing, there’s no way to know how free of contaminants it really is.”

It’s also a good idea for consumers to reach out to the company making their cat’s favorite food brand and inquire about testing and quality control standards, experts say.

“Pet owners should take action and urge brands and retailers to ensure toxic chemicals and plastics are not hiding in cat food and its packaging,” Babadi said. “Pets, as part of our families, deserve food that is safe from toxic chemicals.”

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