- Researchers are still seeking to understand how microplastics impact the cardiovascular system.
- One study’s results identified polymer types in human blood from blood donors and broke down the most common types, sizes, and characteristics.
- The results support the idea that the bloodstream carries microplastics throughout the body and that microplastics may pose an increased risk for cardiovascular problems.
Evidence continues to grow regarding the presence of microplastics in the human body.
A study recently published in Environmental International examined the makeup of microplastics in human blood. Researchers examined the whole blood of 20 healthy participants.
Eighteen of them had blood that contained 24 polymer types. Most of the microplastics were white and clear fragments.
Researchers point out that this research supports how microplastics travel throughout the body and how microplastics could contribute to specific problems, such as vascular inflammation or changes in blood clotting function.
As noted in this study, “[m]icroplastics (MPs) are defined as synthetic plastic particles that typically range between 1 µm [micrometer] and 5 mm [millimeters] in diameter.”
Humans are commonly exposed to microplastics, which may enter the bloodstream through eating or inhaling them. Previous findings have identified microplastics in the blood and even in clogged arteries, suggesting potential dangers from microplastics to cardiovascular health.
The current study aimed to reveal more information about the makeup of microplastics in blood. Understanding these characteristics can help experts understand how dangerous microplastics may be to people.
Study authors Prof. Jeanette Rotchell, PhD, from the University of Hull in the United Kingdom, and Simon Calaminus, PhD, from Hull York Medical School in the U.K., told Medical News Today:
“Microplastics are prevalent within the general environment and so we wished to identify what type and size were present in the blood. Although other labs have identified Microplastics in the blood, they have not used microFTIR microscopy, which has the benefit of allowing us to identify the size and shape of microplastics present. This is likely to be a crucial parameter which will affect how the body interacts with the presence of these microplastics.”
The researchers collected blood samples from 20 healthy, drug-free university students. They acknowledged that the process of collecting blood samples can expose the blood to microplastics. So, they compared the samples to procedural blank samples to help get an idea of what blood could be exposed to during the collection and study period.
Overall, the researchers analyzed a quarter of each procedural blank and blood sample. They then compared the observed microplastics and chemical additives with known polymer and plastic additive chemicals.
They included particles that had a 70% match or greater with these libraries in their shown results. The team also used an approach called limit of quantification (LOQ) to help adjust for background contamination of samples.
Looking at the blood samples, they found that 18 out of 20 samples contained 24 different polymers. After using the LOQ criteria, they found that only eight out of the 20 samples contained microplastics.
The researchers were then able to identify a number of microplastic types, including polyethylene, ethylene-propylene-diene, and ethylene-vinyl-acetate/alcohol.
In all, only five of the microplastics were above the limit of quantification. Thus results note the presence of a quantifiable amount of microplastics in 40% of participants.
When looking at the characteristics of microplastics, researchers found that most were fragments with a clear or white appearance. They were also able to identify several additive chemicals and plastic alternatives in the blood samples.
The microplastics ranged in size as well, with an average particle length of between 7–3000 µm, and an average particle width of 5–800 µm.
Compared to what previous studies had observed, these particle sizes were much larger, which raises certain questions about the potential health impact.
This research does have some limitations. First, it is hard to account for potential contamination of samples. While the authors of this study did attempt to account for this, there is not yet a standard protocol to account for background contamination in microplastics research.
The researchers also only estimated the mass of microplastic polymers, and they acknowledge that they may have underestimated mass and other values. They also cannot be entirely sure of particle composition based on the 70% match or greater criteria they used, and they were further limited by incomplete organic material digestion and the use of Anodisc filters, specialized aluminum oxide membranes used for particle removal.
Furthermore, the authors acknowledge that since they were only able to examine one-quarter of each blood sample, it is possible they have missed some polymers in their analysis, and there may be the risk of rounding errors. They also acknowledge that polyethylene was in the blank samples.
Heather Leslie, PhD, an independent scientist specializing in analyzing microplastics and additives in humans and ecosystems based in Amsterdam, the Netherlands, not involved in this research, commented that “[t]he study raises lots of questions, especially those connected to the methodology and how particles of such huge sizes could have reached the bloodstream in healthy donors.”
“Was there perhaps something in the sample preparation steps that caused particles to stick together and look like large particles? Were these particles possibly an unchecked contamination coming from the blood draw set up (plastic tubing connecting needle and blood vial perhaps)?” she wondered.
However, Leslie emphasized that the study “is a good start.”
“To confirm these results more studies with microFTIR could be done, with extra attention to any weak or uncertain spots in the current study. Every new analytical method can benefit from improvements over time,” she suggested.
Researchers note that this data points to microplastics traveling throughout the body via the bloodstream.
These microplastics could pose several health risks, including problems with blood clotting, vascular inflammation, immune system changes, and possible buildup of microplastics in organs.
The study authors told MNT that: “There is a significant amount of further work to understand the implication of microplastics. For example, understanding where microplastics move in the blood and if there are areas where they accumulate is key. This will then help us to understand the potential tissues that might be at greater risk.”
While more research is required, the current study points to the potential dangers of microplastics and offers a reflection on what sort of interventions may be necessary to address the problem.
Tracey Woodruff, PhD, MPH, professor and director with Environmental Research and Translation for Health (EaRTH) Center at the University of California, San Francisco, not involved in the study, noted that:
“It is no surprise that plastics that are produced in such high volume are showing up in people. And given that more and more studies are finding adverse health effects, the government should be acting on these early indicators of harm, especially since plastic production is on track to triple by 2030.”