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News from CRIS: Real-time Science - Microplastics and Nanoplastics

October 20, 2025

Plastics are part of our everyday life; we use them to ensure the foods and products we use are safer, more sustainable, and more convenient. As we’ve incorporated plastics into our lives, new questions have been raised about what happens when these materials break down into smaller pieces. In this post, we look at microplastics and nanoplastics.

Let’s unpack what these terms mean, how scientists study them, and what we know so far about their impact.

Top Takeaways:

  • Microplastics and nanoplastics differ mainly by size, which affects how they move through the body and environment.
  • Current evidence shows microplastics and nanoplastics are a minimal risk to human health.
  • Scientists are improving detection methods to better understand real-world exposure and long-term effects of microplastic and nanoplastic particulates.
  • Presence does not equal harm. The size alone doesn’t make a material toxic.

What is plastic?

There isn’t a single, universally accepted definition of plastic. The term broadly refers to a wide range of materials made from compounds that contain polymers, which are long chains of repeating molecules that can be shaped and formed in countless ways.

In general, plastics are synthetic or semi-synthetic polymers engineered to be lightweight, strong, durable, and, when needed, flexible. These materials can be processed through methods such as extrusion, injection molding, vacuum forming, or compression to create fibers, thin films, or molded objects.

Each plastic product is made from specific polymers with distinct chemical structures, giving it unique properties suited to its purpose, whether that’s the flexibility of a grocery bag, the rigidity of a water bottle, or the heat resistance of a medical device.

Learn more about polymers in our post What’s Plastic?

What is microplastic?

Microplastics are small plastic particles less than 5 millimeters in size, which is about the width of a pencil eraser or smaller and larger than 1 micrometer (one thousandth of a millimeter). They typically come from two main sources:

  • Primary microplastics are intentionally manufactured at a small size, such as industrial abrasives.
  • Secondary microplastics form when larger plastic products break down.

Microplastics are found in soil, water, and the air we breathe as well as in foods and cosmetic products.

What is nanoplastic?

Nanoplastics are smaller than microplastics. Nanoplastics are less than 1 micrometer). To put that in perspective, The average width of a strand of hair is about 70 micrometers so 1 micrometer is roughly 1/70th of the width of a strand of hair. This size is microscopic and can not be seen with the naked eye.

Because they’re so small, nanoplastics can behave differently from microplastics or larger materials. Their tiny size means they might move more easily through biological membranes or interact differently with cells in our body.

However, detecting and studying nanoplastics is more complex than microplastic research.

Specialized instruments are needed to measure them, including a combination of spectroscopic (especially SERS and Raman), microscopic (SEM, TEM, AFM), and mass spectrometric (Py-GC/MS, ICP-MS) techniques, which are often integrated with advanced sample preparation and data analysis to help identify nanoplastics.

Scientists are still developing reliable methods to identify and track them in complex environments, such as human tissues. In addition, because microplastics are prevalent in indoor air, they can easily contaminate samples that are being analyzed for microplastics, in the absence of specialized facilities and extreme care.

Why does it matter if a plastic fragment is micro- or nano-sized?

Size matters because it helps determine whether a particle can be absorbed by the body, how far it travels, and how easily we can detect it. For example, if the particle is not taken up by the body, if cannot cause harm. Understanding these differences allows scientists to focus on realistic exposure levels and keep perspective as research continues to evolve.

Size impacts our exposure to micro and nano plastics.

Microplastics and nanoplastics can enter our bodies through what we eat, drink, or breathe. Larger microplastics tend to be filtered out by our body’s natural defenses, like the mucus and cilia in our airways or the digestive system’s barriers.

Smaller nanoplastics, however, are tiny enough that they may pass through some natural defenses and have been detected in certain human organs. However, detection doesn’t mean harm, and scientists are studying to see if it’s having an adverse impact on human health.

Size impacts how our bodies handle microplastics and nanoplastics.

So far, evidence shows that most microplastics pass through the body without being absorbed. Our digestive tract and other biological barriers are remarkably effective at blocking the ability of larger particles to being absorbed.

However, some nanoplastics, those below the size of 20 nm may be small enough to penetrate biological barriers under certain conditions, so researchers are looking to understand if and how that might impact human health.

Size impacts our understanding of our real-world exposure to micro and nanoplastics.

It’s much easier to detect microplastics than nanoplastics, which means most of what we know today comes from studies of larger particles.

Nanoplastics are so small that they’re difficult to measure or even confirm in human tissues, making it challenging to know how much we’re actually exposed to. Many studies that detect plastics in the body rely on indirect evidence or model-based assumptions rather than direct measurement.

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To continue reading the entire blog post, visit: https://cris.msu.edu/news/real-time-science-microplastic-nanoplastic/.