Invisible threat

They are barely visible to the naked eye. Yet they permeate our environment: tiny, persistent plastic particles smaller than five millimetres – known as microplastics. These small plastic particles are produced either by the breakdown of larger plastic items or through internal addition to products such as cosmetics and cleaning agents. Even smaller particles, ranging from one to 1,000 nanometres, are classified as nanoplastics.

The particles make their way into the environment and, ultimately, our food chain. Everyone inevitably ingests plastic particles through breathing, eating, and drinking, although the exact quantity varies considerably. In extreme cases, intake can reach up to five grammes of plastic per week, although average consumption is believed to be significantly lower. The widespread presence of microplastics in our ecosystems is now acknowledged as a growing issue, with ecological consequences and highly likely serious implications for human health.

Microplastics from packaging

There is now no doubt that microplastics enter food and beverages through the regular use of packaging. This occurs via mechanical actions, such as friction and pressure, as well as through chemical degradation processes. Packaging materials in direct contact with hot or fatty foods – such as plastic bottles, cups, and cling film – are particularly affected.

“Several studies based on consistent and robust measurement methods show that the typical use of plastic packaging results in the formation of microplastics in food,” explains Dr. Jane Muncke, Managing Director of the Food Packaging Forum. One such example is a study conducted by Columbia University in New York, where scientists examined mineral water in plastic bottles from three different brands.[1] The results are striking: between 110,000 and 370,000 particles were detected per litre of water – the vast majority being polyethylene terephthalates (PET).

In light of growing concerns about the potential health risks posed by microplastics, the European Union and other organisations are funding numerous research projects, including the five CUSP projects. These initiatives aim to measure population exposure, investigate the toxicological properties of microplastics, and identify potential health effects. Among the most prominent is the CUSP project ‘PlasticsFatE’ (Plastics Fate and Effects in the Human Body), which will run until 31 March 2025 and in which the University of Bayreuth is playing a leading role. The team is examining the presence of micro- and nanoplastics in various complex matrices such as food, consumer goods, and relevant environmental media (air, drinking water, soil); the fate of these particles within the human body, their transport through biological barriers, and their possible cytotoxic effects.[2]

Possible promotion of inflammation and cancer

Some studies suggest that microplastics can cause inflammation and other adverse effects in the body. However, research on the precise mechanisms and long-term consequences remain insufficient, preventing any definite conclusions. In the meantime, a team from the University of Vienna has investigated the interactions of micro- and nanoplastics and colon cancer cells. The researchers observed that, unlike other foreign bodies of biological origin, the particles do not degrade due to their chemical composition, which the body cannot process. Furthermore, there is “preleminary evidence that micro- and nanoplastics increase the migration of cancer cells to other parts of the body, potentially promoting tumour metastasis. This effect will now be investigated in a follow-up study.” The study has confirmed recent findings that micro- and nanoplastics influence cell behaviour, and may contribute to disease progression, explained Dr. Lukas Kenner, one of the study’s lead researchers.[3] 

A final risk assessment cannot yet be made

With the data currently available, a conclusive risk assessment of the effects of micro- and nanoplastics on humans is not yet possible. This is because a robust risk assessment requires both an evaluation of the hazard potential and comprehensive information on human exposure levels. However, reliable data on both aspects is currently lacking. “Scientists are working hard on this,” comments Jane Muncke.

According to Muncke, one of the main challenges is the heterogeneity of the measurement methods. Scientists worldwide employ varying techniques to identify and quantify plastic particles, from sampling to analysis and data evaluation. This makes it difficult to compare the results. Quality control also remains challenging. Working conditions throughout sampling and analysis must be as plastic-free as possible to avoid contamination. A pilot study published in 2021 suggests that researchers may sometimes inadvertently contaminate their own samples with microparticles – from their clothing, for example.[4] 

Although initial studies suggest potential health risks, there is no scientific evidence of direct harm caused by microplastics as of now. Nevertheless, consumers increasingly perceive plastics as a hazard: according to a Greenpeace study, 80 percent of people are concerned about the possible effects of plastic on health.[5]

Glass packaging is chemically less complex

But what alternatives do consumers have? It is worth examining the chemical composition of packaging materials: “Plastic packaging is highly chemically complex because it consists of various types of polymers and additives, as well as numerous chemical contaminants and reaction by-products,” explains Jane Muncke. These chemicals can leach over time and migrate into packaged goods, particularly into hot, fatty, or acidic foods. “Paper packaging is also highly complex and, due to its lack of barrier properties, is often thinly coated with plastic or contains PFAS.”

In contrast, glass has low chemical complexity, is chemically inert, and therefore releases far fewer harmful substances. For this reason, glass is often considered a safer alternative for packaging a variety of foods.

Moreover, glass is unproblematic as a reusable packaging, which is not necessarily the case with plastics: reusable plastic bottles not only release their contents but may also absorb detergents from cleaning agents or other chemical compounds, which can then be released again during subsequent use. Additionally, plastic containers are subjected to heat and mechanical friction during cleaning, further contributing to the release of micro- and nanoplastics. In contrast, no increased levels of plastic particles have been detected in reusable glass bottles.

Reducing the use of plastic

Microplastics and nanoplastics represent a complex and serious challenge for both the environment and human health. Research is still in its early stages and many questions remain unanswered. Nevertheless, evidence already suggests that reducing plastic and choosing alternatives such as glass can have positive effects. A mindful approach to packaging, alongside the advancement of scientific research are crucial steps toward minimising the influence of microplastics and safeguarding our health.
 

[1] Naixin Qian et.al. (2024): Rapid single-particle chemical imaging of nanoplastics by SRS microscopy https://pubmed.ncbi.nlm.nih.gov/38190543/
[2] https://www.toek1-laforsch.uni-bayreuth.de/en/research/microplastic/index.html
[3] Microplastics role in cell migration and distribution during cancer cell division https://www.sciencedirect.com/science/article/pii/S0045653524003564?via%3Dihub
[4] C. Gwinnett, R.Z. Miller (2021): Are we contaminating our samples? A preliminary study to investigate procedural contamination during field sampling and processing for microplastic and anthropogenic microparticles. https://www.sciencedirect.com/science/article/abs/pii/S0025326X21011292#! [5] Greenpeace (2024): People vs. Plastic https://www.greenpeace.org/international/publication/66181/global-plastics-treaty-survey-results