The accumulation of evidence concerning the existence of microplastics within the human body is mounting.

In a recent publication in Environmental International, a study delved into the composition of microplastics found in human blood. The research involved analyzing the whole blood of 20 healthy individuals.

Among these participants, 18 exhibited blood samples containing 24 different polymer types. Predominantly, the microplastics detected appeared as white and clear fragments.

This investigation underscores the journey of microplastics within the human body and suggests potential implications. Specifically, researchers highlight the possible association between microplastics and issues such as vascular inflammation or alterations in blood clotting mechanisms.

Discovery: Substantial Microplastic Particles Detected in Human Blood

As outlined in this investigation, microplastics (MPs) are described as synthetic plastic particles typically ranging from 1 µm (micrometer) to 5 mm (millimeters) in diameter.

Human exposure to microplastics is common, with potential entry into the bloodstream occurring through ingestion or inhalation. Prior research has identified microplastics in blood samples and even in arterial blockages, hinting at potential cardiovascular health risks associated with microplastic exposure.

The objective of the present study was to provide further insights into the composition of microplastics found in blood, aiming to elucidate potential health hazards.

Researchers collected blood samples from 20 healthy, drug-free university students, acknowledging the potential for microplastic contamination during the sampling process. To address this, they compared the blood samples with procedural blank samples to assess potential contamination sources.

Overall, a quarter of each procedural blank and blood sample underwent analysis. The observed microplastics and associated chemical additives were compared with known polymer and plastic additive chemicals. Only particles with a 70% match or higher with these libraries were included in the results. The researchers also employed a limit of quantification (LOQ) approach to adjust for background contamination.

Analysis revealed that 18 out of 20 samples contained 24 different polymers, with microplastics detected in eight out of 20 samples following LOQ criteria. Various microplastic types, including polyethylene, ethylene-propylene-diene, and ethylene-vinyl-acetate/alcohol, were identified.

However, only five of the microplastics exceeded the limit of quantification, indicating a quantifiable presence in 40% of participants.

Characteristics of the microplastics included predominantly clear or white fragments, alongside identification of additive chemicals and plastic alternatives in the blood samples.

Notably, the microplastics exhibited a broad size range, with an average length ranging from 7–3000 µm and an average width of 5–800 µm. These sizes were considerably larger compared to previous studies, prompting further inquiry into potential health implications.

How accurate are the study findings?

This study does encounter several limitations. Firstly, addressing potential sample contamination poses a significant challenge. While the authors made efforts to mitigate this issue, there lacks a standardized protocol for accounting for background contamination in microplastics research.

Additionally, the researchers solely estimated the mass of microplastic polymers, conceding the possibility of underestimating mass and other parameters. They also express uncertainty regarding particle composition based on the 70% match or greater criteria utilized. Moreover, limitations stem from incomplete organic material digestion and the utilization of Anodisc filters, specialized aluminum oxide membranes employed for particle removal.

Furthermore, the authors acknowledge the examination of only one-quarter of each blood sample, potentially overlooking some polymers in their analysis, and introducing the risk of rounding errors. Notably, polyethylene was detected in the blank samples.

Heather Leslie, PhD, an independent scientist specializing in microplastics and additives analysis in humans and ecosystems based in Amsterdam, the Netherlands, not affiliated with this study, raised questions regarding the methodology’s robustness and the origin of such large-sized particles in healthy donors’ bloodstream.

Leslie speculated on potential causes, such as sample preparation steps inducing particle aggregation or unchecked contamination from the blood draw setup (e.g., plastic tubing connecting needle and blood vial).

However, Leslie emphasized the study’s significance as a starting point. She suggested conducting further studies utilizing microFTIR, paying particular attention to weak or uncertain aspects in the current study. Leslie underscored the continual improvement potential of every new analytical method through successive studies.