Microplastics Break Down in Cattle Rumen — Study Warns They Could Reach Meat and Milk

A new laboratory study published in the Journal of Hazardous Materials shows microplastic particles interact with microbes in the rumen of grazing livestock and can fragment into smaller pieces during digestion. Researchers say this process alters microbial fermentation and raises concerns that plastics could move through the food chain into meat and milk.

What the Researchers Did

The team recreated rumen conditions in the lab and exposed the simulated digestive environment to microplastic samples that varied by polymer type, particle size and concentration. The experiments were designed to mimic environmental exposures that grazing animals encounter through feed, soil and water.

Key Findings

The study found that rumen microbes respond strongly to microplastics, with the most pronounced reactions triggered by the smallest particles. Rather than simply passing unchanged through the digestive tract, some plastics were partially broken down and appeared to alter fermentation processes in the rumen.

'Our study shows for the first time that microplastics do not simply pass through the digestive tract of farm animals. Instead, they interact with the gut microbiome, alter fermentation processes, and are partially broken down,'

— co-author Jana Siefert

Why This Matters

Microplastics are defined as plastic fragments 5 millimeters or smaller. When these particles fragment further inside animals, they produce tinier pieces that are more likely to penetrate tissues. Previous research has found microplastics can accumulate in blood, organs and tissues in wildlife and humans, so the potential for contamination of meat and milk warrants further investigation.

'Plastic pollution isn't just an environmental issue "out there." It has direct biological consequences for farm animals — and potentially for humans — through the food chain,'

— co-author Cordt Zollfrank

What Comes Next

The authors call for additional studies to quantify how much plastic reaches edible tissues and milk, to assess potential health risks, and to trace real-world exposure routes on farms. In the interim, they recommend practical measures to reduce plastic contamination in agricultural settings.

Practical Steps to Reduce Exposure

Simple actions can limit plastic contamination: reduce and avoid single-use plastics, replace plastic equipment and packaging where feasible, manage farm waste carefully, and limit plastic contact with animal feed and water sources.