Scientists may be overestimating amounts of microplastics in the environment, and the culprit is lab gloves
Recent studies increasingly reveal the presence of tiny plastic particles, known as microplastics, in areas where they should not exist, including within the human body and in our food, water, and air.
Identifying and quantifying microplastics poses significant challenges due to their diminutive size, which can vary from being as large as a ladybug to as small as an eighth of a red blood cell.
Furthermore, avoiding unintentional contamination during sample collection is particularly difficult, as microplastics are pervasive in our environment. As a consequence, many research findings may report inflated estimates of microplastics.
A study published in March 2026 by our team at the University of Michigan underscores that even when adhering to established methodologies, certain techniques employed to analyze environmental microplastics can inadvertently compromise the validity of the results.
The study
Our team, comprised of chemists from the University of Michigan, embarked on a project to quantify the levels of microplastics inhaled by residents of Michigan and to assess how this exposure varies by location.
In preparing our samples, we meticulously followed standard protocols, which included eschewing plastics in the laboratory, donning non-plastic attire, and utilizing a specialized chamber designed to minimize potential contamination from ambient laboratory air.
Despite these rigorous precautions, we recorded air particle counts exceeding 1,000 times those found in previous studies. Recognizing that these figures appeared implausible, we initiated an investigation into the source of this anomaly.
The culprit: Lab gloves
Our investigation led to the identification of laboratory gloves, typically recommended for use in scientific practices, as a potential source of contamination. These gloves can transfer particles to the surfaces of our samples, specifically to small metal sheets utilized for capturing aerosolized material from the air. This transfer ultimately contributed to an inflated perception of microplastic prevalence in our findings.
Specifically, we identified that the contamination stemmed from stearate salts, which are incorporated into gloves to facilitate their release from molds during manufacturing. When gloves come into contact with laboratory apparatus, these salts can adhere to surfaces. While stearate salts are not microplastics, their molecular structure is akin to that of polyethylene, the most common environmental plastic, complicating accurate identification.
The standard method employed by researchers to detect microplastics relies on vibrational spectroscopy, which examines how particles interact with light to produce what is known as a chemical fingerprint.
Due to the structural similarity between polyethylene and stearate salts, their interactions with light exhibit similar characteristics.
Consequently, there is a possibility that residues from gloves may be misclassified as microplastics. As researchers increasingly turn to automated techniques to expedite their analyses, there is a heightened risk that glove contamination could be misinterpreted as environmental microplastics, leading to exaggerated estimates.
How widespread is this contamination?
In order to assess the extent of this contamination issue, we examined a variety of glove types. We simulated handling scenarios with seven different types of gloves, calculating the quantity of particles that could be erroneously attributed to environmental microplastics based on prevalent analytical methods.
Our findings indicated that gloves could contribute more than 7,000 particles per square millimeter that might be mistakenly identified as microplastics. This could result in an inadvertent overestimation of microplastic prevalence in environmental research during sample handling with gloves.
Even more alarmingly, we found that a significant portion of these particles measured under 5 micrometers in size. Microplastics in this size range pose greater risks to human health and ecosystems due to their propensity to infiltrate cellular structures. Inflated count data for such small microplastics could undermine the integrity of studies crucial for informing future policies and regulatory frameworks.
Moving forward
In order to mitigate contamination risks, we recommend that researchers refrain from using gloves while conducting microplastic studies. If glove usage is deemed necessary, especially when handling biological samples for personal safety, we advise selecting gloves manufactured without the inclusion of stearates.
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