Scientists may be overestimating the amount of microplastics in the environment – and the culprit is lab gloves

University of Michigan chemists discovered that laboratory gloves contaminate microplastic research samples, causing scientists to drastically overestimate environmental microplastic levels. When the team measured air samples to study microplastic inhalation in Michigan, they found plastic counts over 1,000 times higher than previous reports—traced to stearate salts used in glove manufacturing that transfer to equipment during handling. The stearate particles mimic polyethylene's chemical signature under vibrational spectroscopy, making them indistinguishable from actual microplastics using standard detection methods. Testing seven glove types showed they can deposit over 7,000 particles per square millimeter that get misidentified as microplastics, with particularly serious implications since most were smaller than 5 micrometers—the size range that most easily penetrates human and ecosystem cells. The researchers recommend avoiding gloves in microplastic studies, using stearate-free alternatives when necessary, and developing methods to differentiate contaminated datasets.