A sweeping investigation of popular cat food found toxic plastic contaminants, glyphosate and heavy metals in nearly all tested products, raising concern about what pets repeatedly consume. The Clean Label Project released the analysis Friday after examining wet, dry, air dried and freeze dried foods.

The Colorado nonprofit tested 100 top selling cat foods from 62 brands for more than 122 contaminants. Lead appeared in 99% of samples, cadmium in 96% and arsenic in 94%.

Contamination varied according to product type and protein source, including poultry, beef, fish and seafood. Toxins were detected even in products promoted as natural or nutritionally superior, challenging the assumption that premium ingredients and higher prices necessarily deliver cleaner food.

Molly Hamilton, the Clean Label Project’s executive director and the report’s author, said many cats eat the same foods daily with little variation. That routine may create continuing exposure to contaminants that can accumulate in their bodies over their lifetimes.

Heavy metals naturally occur in soil, water and air, although pollution from agriculture, industry and mining can increase and spread contamination. According to the report, plastics and other contaminants may also enter pet food during manufacturing.

Cadmium is classified as a human carcinogen and can harm the kidneys and bones, while accumulated lead damages nearly every major organ system. Inorganic arsenic, the form 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 lead level is considered safe for people, and children can absorb up to 50% of ingested lead, compared with about 10% for adults.

Hamilton said cats and other small pets also absorb more than larger animals, yet few regulations govern contaminants in pet food. She noted that many existing guidelines were designed for farm animals rather than kittens or older housecats.

Fish and seafood products had the strongest association with mercury and cadmium. Mercury levels were about 18 times higher and cadmium levels about 2.5 times higher in fish or seafood foods than in products made with other proteins.

Wet seafood products contained nearly 28 times as much mercury as wet foods made with other meats, particularly poultry. Nearly 85% of poultry products met the Clean Label Project’s purity standard, compared with 25.7% of fish and seafood products.

Poultry presented its own contamination pattern, however. Hamilton said chicken products performed better for mercury and cadmium but showed higher rates of lead and herbicides, while some fish products still met the organization’s certification requirements.

Glyphosate, agriculture’s most widely used herbicide, was detected in 37% of products. Foods containing more plants among their first 10 ingredients had higher levels, and products with five plant ingredients had nearly four times as much glyphosate as those with one.

The analysis also detected di(2-ethylhexyl) phthalate, known as DEHP, in about half of the products. The highest levels appeared in canned and pouch foods, and contamination could potentially occur through contact with PVC tubing or other equipment during farming or food processing.

Ryan Babadi, science director for Toxic Free Future, called the analysis reasonably conducted and urged major retailers to require suppliers to eliminate harmful chemicals from food and packaging. Bisphenols, including BPA, appeared less frequently, suggesting such chemicals can be avoided.

The Pet Food Institute, which represents cat food manufacturers, said companies use comprehensive food safety and quality assurance programs. CEO Elise Fennig said those measures include ingredient specifications, supplier verification, testing protocols, traceability systems and science based preventive controls.

The research had limitations because each product came from only one batch, meaning the analysis could not capture possible variation between batches. It compared contamination across product categories but did not determine whether any specific food would harm a cat.

The report advised varying seafood diets with chicken or other proteins to limit daily mercury and cadmium exposure. It also suggested choosing wet or air dried products to reduce lead exposure and avoiding foods with plants among the first 10 ingredients to potentially lower pesticide exposure.

Labels alone may not reveal the full contamination picture. In more than one third of products, the first listed ingredient did not reliably indicate the food’s contents or predict which contaminant would appear at the highest level.

Hamilton recommended contacting manufacturers to ask whether they test their food, how often they conduct testing and what quality control standards they follow. Babadi also encouraged pet owners to press brands and retailers to keep toxic chemicals and plastics out of cat food and packaging.