The Hidden Complexity of Studying Microplastics in the Human Body

Researching microplastics inside the human body is a challenging task because it is a very new field of study. Scientists are often forced to use analytical techniques that were originally developed for different purposes. This creates significant obstacles when trying to isolate and identify plastic particles within complex biological samples.

A few years ago, researchers began considering human exposure to plastics more seriously. The initial approach was straightforward: test blood samples and see what was inside. When Cassandra Rauert, a researcher in this field, tested a small amount of her own blood, she detected extremely high levels of polyethylene. This result seemed illogical to her. She did not believe her diet, which was low in plastic-packaged foods, could account for such high concentrations. This discrepancy led her to question whether there were flaws in the analytical methods being used.

Rauert and her team assessed the reliability of current measurement techniques for finding microplastics in blood. They discovered a critical problem: lipids and fats can cause false positives for polyethylene. Lipids are composed of the same chemical building blocks as polyethylene. Consequently, when analyzed using standard instruments, lipids look identical to polyethylene signals. If researchers do not examine the data with extreme care, they may mistake a signal from natural body fats for plastic pollution.

In a paper published last year, Rauert’s team identified that 18 previous studies on microplastics in human blood suffered from this specific issue. The goal of their publication was to alert the scientific community that they must carefully interpret the data coming from their instruments. There is a strong potential for lipids to be misidentified as polyethylene.

Rauert noted that, to their knowledge, the authors of those 18 previous studies were unaware of this interference. They had not considered the possibility that fats in the blood could mimic plastic signals. Rauert emphasized that future studies must account for this potential error to ensure accuracy. Ignoring this factor renders many existing findings questionable.