Researchers have found widespread microplastic contamination in milk and cheese, raising fresh concerns over food safety and highlighting the role of packaging and processing in pollution.
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A recent study, published in npj Science of Food, investigated microplastic contamination in milk, fresh cheese, and ripened cheese, providing one of the most detailed assessments yet of plastics in dairy products. The research team used advanced spectroscopic techniques to analyze the size, shape, colour, and concentration of microplastics in these widely consumed foods.
Microplastics: Why Should We Care?
Microplastics, defined as plastic particles between 0.1 µm and 5,000 µm, are pervasive, appearing in oceans, rivers, sediments, and even inside living organisms. The problem is so extensive because of their durability and the widespread use of plastic products. They often result from the breakdown of larger plastics or are directly released, for example, from synthetic fibres.
Their persistence has raised growing public health and ecological concerns, particularly through dietary exposure, which is now considered the main way that humans ingest microplastics.
Previous studies have found microplastics in drinking water, seafood, beverages, honey, salt, and, more recently, dairy products. The dairy sector is especially at risk because of extensive plastic use in production and packaging, including feed handling, milking equipment, and storage. Despite increasing awareness, research into microplastics in dairy remains limited.
This study aimed to investigate further, informing food safety risk assessments and targeted mitigation.
How the Study Was Conducted
The researchers analysed 28 dairy samples bought from retail markets: four ultra-high temperature (UHT) milk samples, ten fresh cheeses (aged under one month), and 14 ripened cheeses (aged over four months). Samples were kept frozen and processed in a cleanroom laboratory (ISO 14644-1:2015 Class 7) to minimise external contamination.
Each sample was thawed, homogenised, and divided into representative portions. Organic material was removed using a combined enzymatic and chemical digestion method, including trypsin, potassium hydroxide (KOH), and EDTA.
Microplastics present in the samples were then separated by density flotation in an oversaturated sodium chloride solution and filtered through 3.0 µm silver membrane filters.
Identification and quantification were carried out using Fourier-transformed infrared micro-spectroscopy in attenuated total reflectance mode (μ-FTIR-ATR).
Each particle was scanned multiple times and matched to reference libraries with more than 80 % confidence. Quality control included procedural blanks and recovery tests, with an average recovery rate of 84 %. Statistical analysis used linear models with Bonferroni-adjusted comparisons to identify significant differences between product types.
What was Uncovered?
Microplastics were detected in 26 out of 28 dairy samples, with a total of 266 plastic particles identified across 20 different polymer types. Their sizes ranged from 24.0 µm to 4,817 µm, with an average of 243.7 µm. The most common polymers were poly(ethylene terephthalate) (PET), polypropylene (PP), and polyethylene (PE).
Smaller particles (51–100 µm) were the most common, making up around a third of those detected. Researchers linked this to contamination from packaging, processing equipment, or airborne particles during production.
Most of the microplastics were irregular fragments (77.4 %), with fibres (22.2 %) and a small number of beads (0.38 %) also present. They ranged in colour but were predominantly brown (15.0 %), black (9.77 %), or grey (68.4 %).
Concentrations varied considerably by product type: ripened cheese had the highest contamination at 1,857 microplastics/kg, followed by fresh cheese at 1,280 microplastics/kg and milk at 350 microplastics/kg.
These differences were linked to the intensity of processing, fat content, and packaging materials. Cheese production, particularly whey removal, is the most likely culprit for increasing microplastic concentrations in ripened cheeses. However, the study did find that there was variation in microplastic contamination between commercial milk brands.
Why This Matters for Food Safety and the Environment
The study's findings emphasised the importance of including microplastics in food safety assessments. The diversity of polymers and particle sizes identified points to multiple contamination pathways, from environmental exposure to processing and packaging.
To begin to target such widespread contamination, the researchers suggested targeted interventions such as improving packaging materials, enhancing hygiene protocols, and reducing the use of synthetic textiles in production. Regular monitoring, particularly during cheese maturation and packaging, could also help reduce contamination.
Given the scale of dairy consumption worldwide, minimising microplastics in these products is important for both public health and environmental sustainability. This research provides key insights for regulators and industry stakeholders working to protect food quality and curb plastic pollution.
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How Can it Be Tackled?
The study represents an important step in mapping microplastic contamination in dairy, identifying a range of polymer types and potential sources, including feed, processing equipment, and packaging. Future research could extend to plant-level studies covering the full production chain to pinpoint where contamination occurs and test specific interventions.
Improving detection methods for even smaller particles and studying long-term health impacts will also be important. With public concern over microplastics on the rise, continued research is required to safeguard consumers and support more sustainable production practices.
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Source:
Visentin, E., & et al. (2025). Assessing microplastic contamination in milk and dairy products. npj Sci Food 9, 135. DOI: 10.1038/s41538-025-00506-8, https://www.nature.com/articles/s41538-025-00506-8