Plastics exposure evident in human tissues

Our environment is contaminated with tiny fragments of plastic — the remnants of the plastic pollution littered on land and in the water and air. Animals and humans can ingest these particles, with uncertain health consequences. Research in wildlife and animal models has linked micro- and nanoplastic exposure to infertility, inflammation and cancer, but health outcomes in people are currently unknown.

Microplastics are defined as plastic fragments less than 5 mm in diameter. Nanoplastics are even smaller, with diameters less than 0.050 mm.

Research presented at the American Chemical Society (ACS) Fall 2020 Virtual Meeting & Expo has examined the presence of micro- and nanoplastics in human organs and tissues.

“You can find plastics contaminating the environment at virtually every location on the globe, and in a few short decades, we’ve gone from seeing plastic as a wonderful benefit to considering it a threat,” PhD researcher Charles Rolsky said.

“There’s evidence that plastic is making its way into our bodies, but very few studies have looked for it there. And at this point, we don’t know whether this plastic is just a nuisance or whether it represents a human health hazard.”

Previous studies have shown that plastics can pass through the human gastrointestinal tract, but Rolsky and co-researcher Varun Kelkar — a graduate student in the lab of Rolf Halden at Arizona State University — are investigating if the tiny particles accumulate in human organs and how to detect them.

Collaborating with postdoctoral researcher Diego Mastroeni, the team obtained samples from a large repository of brain and body tissues that was established to study neurodegenerative conditions, such as Alzheimer’s disease. Samples were taken from lungs, liver, adipose tissue, spleen and kidneys –– organs likely to be exposed to, filter or collect plastic monomers and microplastics.

To develop a method and test it, the team applied flow cytometry to an experimental sample spiked with nano/microplastic beads. The researchers also created a computer program that converted information on plastic particle count into units of mass and surface area. They plan to share the tool online so that other researchers can report their results in a standardised manner.

“This shared resource will help build a plastic-exposure database so that we can compare exposures in organs and groups of people over time and geographic space,” Halden said.

Using mass spectrometry, the researchers analysed 47 human liver and fat tissue samples. The team found plastic contamination in the form of monomers — or plastic building blocks — in every sample. Bisphenol A (BPA), still used in many food containers despite health concerns, was found in all 47 human samples.

Taken together, to the researchers’ knowledge, the study is the first to examine monomer, nano- and microplastic occurrence in human organs from individuals with a known history of environmental exposure.

“The tissue donors provided detailed information on their lifestyle, diet and occupational exposures,” Halden said.

“Because these donors have such well-defined histories, our study provides the first clues on potential micro- and nanoplastic exposure sources and routes.”

Should people be concerned about the high detection frequency of plastic components in human tissues?

“We never want to be alarmist, but it is concerning that these non-biodegradable materials that are present everywhere can enter and accumulate in human tissues, and we don’t know the possible health effects,” Kelkar said.

“Once we get a better idea of what’s in the tissues, we can conduct epidemiological studies to assess human health outcomes. That way, we can start to understand the potential health risks, if any.”

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