Laboratory Gloves May Distort Microplastic Analysis Results

Laboratory gloves, commonly utilized in scientific experiments, have been found to substantially increase the quantity of microplastics in samples. Particles that remain on the surface of these gloves can contaminate materials for analysis and are mistakenly identified as plastic, resulting in exaggerated measurement outcomes. This alarming discovery was reported by Science Alert.

Microplastics are tiny plastic particles that arise from the breakdown of plastic waste. They have been detected in water, food, air, and even within the human body. However, due to their minuscule size, identifying these particles can be quite challenging. Microplastic particles can range from several millimeters to significantly smaller than a blood cell, complicating their identification.

Chemists from the University of Michigan conducted a study to ascertain the amount of microplastics that individuals inhale outdoors. During the experiment, they adhered to standard protocols: avoiding plastic materials in the laboratory, wearing clothing devoid of synthetic fibers, and working in a specially equipped chamber designed to minimize contamination. Despite these precautions, the researchers discovered that the air samples contained particle counts exceeding 1,000 times more than those found in previous studies.

Upon thorough investigation, it was revealed that the source of contamination was indeed the laboratory gloves. These gloves left behind tiny particles on the sample surfaces, which were then erroneously identified as microplastics. The particles in question are stearate salts, which are used in the manufacturing of gloves to facilitate their removal from molds. They can be transferred to equipment and samples during contact.

Stearate salts are not microplastics themselves, but they share a similar structure with polyethylene—the most common type of plastic. Due to this resemblance, distinguishing them during analysis proves difficult. Researchers employ vibrational spectroscopy, a method that identifies materials based on their interaction with light. However, because of the structural similarities between polyethylene and stearates, the signals they generate are nearly identical, leading to frequent errors in the system.

The scientists tested seven types of gloves and simulated working with laboratory equipment. It was found that the gloves could introduce over 7,000 particles per square millimeter, which are mistakenly considered microplastics. Most of these particles were smaller than 5 micrometers—this size is particularly concerning as such particles can more easily penetrate cells.

The authors of the study emphasize that this issue could significantly impact the results of scientific research used to shape environmental policy. Inflated figures may create a false impression of the scale of the microplastic problem in the environment.

To avoid such errors, researchers recommend refraining from using gloves during microplastic analysis whenever possible. If gloves are necessary, they advise opting for stearate-free gloves, such as those designed for the electronics industry. The team has also developed methods to help distinguish these particles in already collected data.

Scientists stress that even if the actual quantity of microplastics is lower than previously thought, their presence still raises concerns due to the potential negative impacts on human health and ecosystems.