Every day it seems like new research is discovering tiny plastic particles called microplastics in places they shouldn’t be: in our bodies, in our food, water, and air.
However, finding and identifying microplastics is extremely difficult, especially given their small size. A single microplastic can be as large as a ladybug or as small as one-eighth of a red blood cell.
Additionally, because these plastics are virtually ubiquitous, it can be difficult for researchers to avoid unintentionally contaminating samples. As a result, much of this research may overestimate the number of microplastics.
In a new study published in March 2026, our team found that using certain methods to measure environmental microplastics can contaminate results, even when established protocols are followed.
Microplastics are small plastics that are emitted from plastic waste. They exist in the environment, waterways, and even in humans.
the study
We are chemists at the University of Michigan and work in a collaborative team. We set out to understand how much microplastics people in Michigan are breathing in when they’re outdoors, and whether it depends on where they live.
When preparing the samples, we followed all standard protocols while conducting the study. We avoided the use of plastic in the lab, wore non-plastic clothing, and also used a special chamber to reduce potential contamination from the lab air.
Despite these precautions, the number of plastics in the air was found to be more than 1,000 times higher than previously reported. I knew these numbers weren’t right, but what happened?
Culprit: Lab gloves
After a long journey to identifying the source of the contamination, we discovered that the use of lab gloves, which the scientific community recommends as a best practice, can cause particles to stick to the surface of the sample. In this case, it’s a small metal sheet used to collect deposited material from the air. Furthermore, this particle led to an overestimation of microplastic abundance in our study.
Here’s how: Particles identified as stearates are used to ensure that the gloves release cleanly from the mold during the manufacturing process. Using gloves to handle lab equipment transfers particles to anything you come in contact with. Stearates are similar to soap molecules, and while they may not be good for you if you eat a lot of them, they are not harmful to the environment like microplastics.
Although stearate is not itself a microplastic, it is structurally similar to polyethylene, the most common type of plastic in the environment. This structural similarity makes it difficult to tell them apart using the most common tools scientists use to determine whether a particle is plastic.
Researchers use vibrational spectroscopy to identify microplastics. This requires measuring how particles interact with light to produce what scientists call chemical fingerprints.
Polyethylene and stearate have very similar structures and therefore interact with light in similar ways.
As a result, at least in some cases, particles from gloves can be incorrectly identified as microplastics. As more researchers rely on automated methods to speed up analysis, glove residues are increasingly being mistaken for microplastics, potentially over-reporting microplastics in the environment.
How widespread is this contamination?
To find out how prevalent this contamination is, we looked at different types of gloves. We mimicked the contact of seven types of gloves when handling laboratory equipment and counted the number of microplastics that would be incorrectly attributed to the environment if we followed the most common approach.
We found that gloves can contribute more than 7,000 particles per square millimeter that are misidentified as microplastics. This finding means that researchers may be unconsciously overestimating the amount of microplastics in the environment when handling samples with gloves.
More worryingly, the particles were found to be less than 5 μm in size. Microplastics in this size range can easily enter cells and have a significant impact on human and ecosystem health. The use of laboratory gloves inflates the number of microplastics in this size range, potentially jeopardizing research that influences future policy and regulation.
How handling samples with gloved hands leads to overestimation of plastics.
Madeline Clough
move forward
To avoid contamination, scientists recommend avoiding the use of gloves while conducting research on microplastics. If that is not possible, for example in the case of biological samples where researchers must wear gloves to protect themselves, we recommend gloves made without stearate, such as those designed for electronics manufacturing. To recover old datasets that may have been contaminated, we developed a method that helps distinguish chemical fingerprints.
Science is an iterative process. Emerging research areas involving environmental microplastics are posing new challenges to the scientific community. As we address these new challenges, we will encounter difficulties such as unforeseen contamination.
Although we had to discard the initial data set, we hope that the lessons learned about glove contamination will be passed on to other scientists. Additionally, we plan to continue our research on microplastic pollution in Michigan’s air, but this time without gloves.
It’s important to note that even if the abundance of microplastics in the environment is lower than researchers originally thought, any amount of microplastics can be problematic given their negative impact on human health and ecosystems.
