It seems like every day a new study finds tiny plastic particles called microplastics where they should not be: in our bodies and our food, water and air.
Yet finding and identifying microplastics is extremely challenging, especially given their small size. One microplastic can range from as large as a ladybug to as small as an eighth of a red blood cell.
In addition, it can be hard for researchers to avoid unintentionally contaminating their samples, because these plastics are practically everywhere. As a result, much of this research may be overestimating the number of microplastics.
In a new study published in March 2026, our team found that, even when following established protocols, using certain methods to measure environmental microplastics can potentially contaminate the results.
Microplastics are tiny plastics shed from plastic waste. They are found in the environment, waterways and even the human body.
The study
We are chemists at the University of Michigan working in a collaborative team. We set out to understand how many microplastics Michiganders were inhaling when outside, and whether that depended on where they lived.
When preparing our samples, we followed all the standard protocols while conducting our research – we avoided plastic use in the lab, wore nonplastic clothing and even used a specialized chamber to reduce potential contamination from the laboratory air.
Despite these precautions, we found plastic counts in the air that were over 1,000 times greater than previous reports. We knew these numbers didn’t seem right, so what happened?
The culprit: Lab gloves
After a long path to pinpointing the contamination source, we found that laboratory gloves, which the scientific community recommends using as a best practice, can transfer particles to the surface of our samples – in this case, small metal sheets used to collect material depositing from the air. Moreover, the particles led to an overestimation of microplastic abundance in our study.
Here’s how: The particles, which we identified as stearate salts, are used to help the gloves cleanly release from their mold during the manufacturing process. When gloves are used to handle laboratory equipment, the particles are transferred to anything they touch. Stearate salts are similar to soap molecules – if you eat a lot of them, they’re probably not good for you, but they’re not harmful in the environment in the same way that microplastics are.
While not microplastics themselves, stearate salts are structurally similar to polyethylene, the type of plastic most often found in the environment. This structural similarity makes it difficult to distinguish them using the most common tools scientists use to determine whether a particle is plastic.
Researchers use vibrational spectroscopy to identify microplastics, which entails measuring how the particle interacts with light…
