New study finds microplastics in more than 75% of commercial pet food brands
The investigation tested a variety of pet foods intended for dogs, cats, and hedgehogs. These products came from 19 different brands and covered a wide range of prices.
The foods were chosen to allow comparison of similar flavors across brands, mainly chicken-flavored options for consistency. The researchers purchased six separate packages of each product from different production batches to avoid one-time contamination affecting the results.
From each package, small samples were taken from various spots, ending up with 228 tiny portions weighing one gram each. To find microplastics, the samples were treated with chemicals to break down organic parts, leaving behind tiny plastic particles.
These particles were trapped on fine filters and inspected under a microscope. The particles’ sizes and shapes were recorded, and their chemical makeup was identified using a special scanning method that compares their light absorption to known plastics.
Care was taken to avoid false results caused by particles floating in the air during testing.
Findings from the Analysis
Microplastics appeared in a significant portion of the samples. About 28% of the individual samples had microplastic contamination.
When looking at the full products, 76% contained at least one contaminated sample. Most brands had microplastics present, with only a few showing no signs of contamination.
Less expensive pet foods generally contained more microplastics compared to the high-end products. Foods listing “meat and animal derivatives” as ingredients—often including lower-quality parts—were more likely to be contaminated.
The plastics identified were mainly fibers and fragments, with fibers making up about 60%. Common plastic types included polyester, polyethylene, polypropylene, and polyacrylamide.
Dry pet foods had more plastic particles per gram than wet ones. Because wet food is less energy-dense, pets eat larger amounts, which leads to greater daily microplastic intake from wet foods despite their lower concentration per gram.
| Parameter | Dry Food | Wet Food |
|---|---|---|
| Microplastic particles/g | Higher | Lower |
| Typical particle types | Fibers & fragments | Fibers & fragments |
| Estimated daily intake* | Lower due to less intake | Higher due to more intake |
*Estimated daily intake considers the amount of food animals consume.
Calculations of Daily Food and Plastic Exposure
The study estimated how many microplastic particles pets might swallow in a day by using different feeding scenarios. These scenarios ranged from moderate to worst-case, depending on how much microplastic was in the food and whether a pet is fed the same brand consistently.
They calculated food intake based on typical energy needs for animals of different sizes—small, medium, and large dogs, plus an average-sized cat. Under moderate conditions, a large dog eating wet food might consume over 300 microplastic particles daily.
Small animals like hedgehogs, often given pet food in gardens or wildlife centers, might ingest between 6 and about 100 microplastic particles daily. Both pets and wild animals eliminate these particles through feces, spreading microplastics into the environment.
Estimated daily microplastic intake varies widely based on food type, brand, and feeding habits. The numbers range roughly from 160 up to over 2,300 particles per day in different situations.
| Animal | Feeding Type | Estimated Daily Microplastic Ingestion |
|---|---|---|
| Large Dog | Wet Food | ~313 particles |
| Hedgehog | Mixed Food | 6 to 105 particles |
| Cat | Various | Varies by scenario |
Microplastic levels in pet foods were found to be higher than those in many human foods, although still lower than in some wild organisms. Effects on animal health have not been assessed, and more research is needed to find the sources of contamination and any risks involved.
