Risks for Inflammation in Human Organs Still Unknown
In a scientific first, researchers have found microplastics in human blood. A recent study reveals that tiny plastic particles can travel within the body via the circulatory system.
The study by researchers from the Department of Environment and Health at Vrije Universiteit Amsterdam and Amsterdam University Medical Center detected tiny pieces of plastic in 77% of participants tested.
This is "the first real-world evidence that plastic particles are absorbed in the human bloodstream," says Dr. Heather Leslie, lead author of the study.
The new study is an important addition to the growing body of research that finds microplastics in various human organs, tissues, blood, and waste matter. Additional research seeks to answer many more questions—especially about human health risks—associated with these man-made materials.
Earlier Studies Prompted Blood Research
Previous research studies identified the presence of microplastics in the placenta and in feces. (Following the discovery of microplastics in human blood, another research team found them in deep lung tissue).
"We were aware that microplastics had been found in human stool, so we hypothesized that they could have crossed barriers and be found in the blood," says Dr. Juan J. Garcia-Vallejo, co-author of the study and associate professor at the Department of Molecular Cell Biology & Immunology, Amsterdam University Medical Center.
In addition, a research study found that infant exposure to microplastics from consuming formula—prepared in polypropylene infant feeding bottles—was higher than previously recognized. The researchers stated that the study’s results highlighted an "urgent need" to assess whether exposure to microplastics at the levels found in the study—as high as 16,200,000 particles per liter—is a risk factor for infant health.
Discovering Microplastics in Human Blood
"What we didn’t know beforehand was if the plastic dust we see in our indoor environment, air, water and food chain gets absorbed into the human bloodstream in amounts that are detectable with our current technology," says Leslie.
The Amsterdam researchers developed a robust and sensitive analytical method to measure plastic particles. That technique would then be applied to measuring the presence of plastic particles with dimensions of 700 nanometers and up in the blood of healthy human volunteers.
Quality control and validation of their analytical techniques were of particular importance to the researchers. To identify and quantify the levels of microplastics in the blood, the researchers used their analytical techniques to measure the quantities in the participants’ blood of five specific polymers commonly used in high volume plastic production: polyethylene terephthalate, polyethylene and polymers of styrene, poly (methyl methacrylate), and polypropylene.
Four of the five polymers were detected in some of the human blood samples, with only polypropylene levels being below the limits of detection of the researchers’ techniques.
"When we got the first data in, we were shocked, even though it validated our hypothesis."
"We went from expecting there to be microplastic in human blood to knowing it is there," says Leslie. "When we got the first data in, we were shocked, even though it validated our hypothesis," adds Garcia-Vallejo.
The results of the research project, called Immunoplast, were published in the scientific journal Environment International. The research program strives to gain more insight into the potential health implications of plastic particulates and actions that can be taken to limit their possible harmful effects.
The Amsterdam researchers recommended further studies to ascertain the health implications of microplastic accumulation in human bodies and whether plastic particle exposure is a public health risk.
Exposure to Microplastics Unavoidable
Microplastics originate from all items made from plastic. As these items wear down during use or at the product’s end of life, plastic fragments are released into the environment. Once released, they "start a big journey waltzing in and out of living beings pretty much unscathed, back into the air and water and earth again," Leslie notes.
According to Garcia-Vallejo, exposure to microplastics through food or drink is the most likely route of entry into humans. Leslie emphasized that plastic, either inhaled with air or ingested with food and water, has a gigantic number of potential sources. That is because plastic pollution is ubiquitous, and tiny shreds of plastic can usually be detected in processed food, vegetables, meat, tap water and bottled beverages. Vast amounts of consumable foods come in contact with plastic packaging.
"We are most concerned about the fine particles that get absorbed, enter the bloodstream, and from there travel to all parts of the body to be deposited in organs and tissues where they can potentially cause inflammation and toxic effects."
Plastic particles in the body can end up in the toilet if they are too big to be absorbed in the lungs or gut. "That is why we are most concerned about the fine particles that get absorbed, enter the bloodstream, and from there travel to all parts of the body to be deposited in organs and tissues where they can potentially cause inflammation and toxic effects," says Leslie.
"The microplastics made today won’t fully degrade for several more generations, so in that sense, I see them as our message to the future: We used a lot of plastic that was incompatible with ecosystems, and we had a hard time figuring out what to do about it," Leslie adds.
Microplastics and Human Health
Regarding the implications that microplastics in the bloodstream have for human health, Leslie explains, "the risk to human health arises when the exposure reaches levels that toxicity starts to kick in." The study showed exposure levels in a small group of humans.
Research is ongoing to determine the plastic in blood levels in larger samples of the human population. More donors need to be measured to get a better idea of the distribution of plastic among the population, Leslie shares. "It is not just about more toxicity research, but also we need to establish the exposure levels in a lot more humans before we can extrapolate to say a human population as a whole," Leslie continues.
There are also currently ongoing European projects designed to determine the threshold levels for toxicity.
"What we do know already comes from the field of particle and fiber toxicology," says Leslie. Some particles or fibers can elicit toxicity, which starts with oxidative stress and inflammatory response. "Chronic inflammation is considered a prelude to many chronic diseases," says Leslie. "We need to figure out if plastic particles cause these kinds of inflammations," explains Leslie.
"My question is, how different is the toxicity of plastic particles from other particles that we know cause human health issues, such as particulates in air pollution?" Leslie asks. Much of the past research into the toxicity of chemical additives that leach out of plastic has shown that exposure to them can lead to endocrine disruptive effects in humans, she says.
However, the human health effects of plastic particles themselves are a nascent research field. At the moment, researchers know more about the toxicity of chemicals that leach out of plastic materials, Leslie confirms. "Microplastic might be toxic because of the additives, the particle getting caught up in biological processes, or a combination of the two," Leslie details. Plastic can also exert what is called particle and fiber toxicity.
Limiting Exposure to Microplastics
The question of what can people do to limit their exposure to microplastics—in terms of it entering their bodies—is "very difficult," says Garcia-Vallejo.
"We need to act on limiting plastic pollution in the environment so that the exposure decreases," he says.
People can best use their voice, become politically active, support civil society groups tackling plastic pollution, talk to their elected representatives, and sign petitions and letters. "In other words, don’t keep it to yourself!" says Leslie.
"Also, think before you purchase something if you want it, need it, and if it needs to be plastic, or if there is another solution to the product’s function," adds Leslie.
Furthermore, design signals intention. "Whenever people design a product, if there is an intention to design plastic pollution out of the product, everything changes," says Leslie. "People making decisions at work about product design or procurement can make a larger scale difference than you or me searching for a supermarket that doesn’t wrap cucumbers in plastic," Leslie continues.
Removing Microplastics from the Body
Currently, there are no known protocols to remove microplastics from the human body.
Still, researchers are confident ways will be found to heal humanity from pollution damage.
"Never underestimate the power of human intention and ingenuity," says Leslie. "We can easily share this planet with 8 billion people without trashing it; it is just difficult for most adults to imagine it," she adds.
*Natasha Spencer-Jolliffe is a freelance journalist and editor. Over the past 10 years, Natasha has reported for a host of publications, exploring the wider world and industries from environmental, scientific, business, legal, and sociological perspectives. Natasha has also been interviewed as an insight provider for research institutes and conferences.
Interview with Juan J. Garcia Vallejo, MD, PhD, MBA, Associate Professor, Dept. Molecular Cell Biology & Immunology, Amsterdam University Medical Center.
Interview with Dr Heather Leslie, formerly Senior Researcher, Dept. of Environment and Health, Vrije Universiteit Amsterdam. Dr Heather Leslie left the VY as of 1st March 2022.