Laboratory gloves could inflate microplastics readings, suggests study

University of Michigan (U-M) researchers say they have found evidence that tiny stearate salt particles released from commonly used nitrile and latex lab gloves may be responsible for false readings.

The particles, although not plastics, do closely resemble microplastics and can skew test results, warn doctoral graduate Maddie Clough and senior author U-M professor of chemistry, macromolecular science and engineering Anne McNeil in RSC Analytical Methods.

The study emerged from another project in which Clough was involved to examine atmospheric microplastics, during which air samplers were prepared with a metal substrate fitted.

Having prepared the substrates wearing nitrile gloves, as recommended, Clough discovered the incidence of microplastics present was thousands of times greater than expected.

After tracing the fault to the gloves, the researchers tested seven types of gloves and the most commonly employed microplastics identification techniques.

On average, they found, there were approximately 2,000 false positives per mm sq area.

Commenting on the U-M website, Clough stated: “The type of contact we tried to mimic touches upon all varieties of microplastics research. If you are contacting a sample with a gloved hand, you’re likely imparting these stearates that could overestimate your results.”

The most effective gloves for combatting false readings, said the researchers, were cleanroom gloves – which are produced without the stearate coating common to other lab gloves.

However, McNeil added that the findings did not imply that microplastics pollution was not a continuing concern.

“We may be overestimating microplastics, but there should be none. There’s still a lot out there, and that’s the problem,” she said.

And while the findings may throw into question the accuracy of some studies of pollution, the U-M team has also designed experiments to better determine the difference between microplastics and stearate salts.

“For microplastics researchers who have these impacted datasets, there’s still hope to recover them and find a true quantity of microplastics,” Clough said.

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