Updated: Researchers from Arizona State University found microplastics and nanoplastics in human organs and tissues in a small-scale study presented at the American Chemical Society's Fall 2020 Virtual Meeting & Expo.
The conclusions and media coverage around the study, however, are being criticized by the American Chemistry Council, which said the ASU study intentionally added the microplastics as part of an effort to develop new detection methods.
ACC criticized what it said was incorrect reporting around that point.
“While some of the stories were corrected, the false information has already spread across the internet and social media,” ACC said. “Moreover, these data have yet to be published in a peer-reviewed journal and thus constitute preliminary results that need additional vetting.”
A news release from ACS announcing the study noted that the ASU researchers did spike some of the human tissues studied with both micro and nanoplastics, as part of their work to study the effectiveness of a potential testing method.
But the ACS release also said that researchers examined samples that they did not spike with any plastics, and found plastic contamination, in the form of monomers, in those samples.
Charles Rolsky and Varun Kelkar, the two graduate students in the lab of Rolf Halden at ASU who did the research, said in the ACS news release that they had wondered if the particles accumulate in human organs.
Microplastics are defined as plastic fragments of less than 5 millimeters, while nanoplastics are even smaller, with diameters less than 0.001 mm. The fragments previously have been found in fish, birds and other wildlife.
The researchers collaborated with Diego Mastroeni to obtain 47 samples from a large repository of brain and body tissues that was established to study neurodegenerative diseases, such as Alzheimer's. The samples were taken from lungs, liver, spleen and kidneys –– four organs likely to be exposed to, filter or collect microplastics.
The researchers developed a method that enabled them to detect dozens of types of plastic components within human tissues, including polycarbonate, PET and polyethylene. They extracted plastics from the samples and analysed them by μ-Raman spectrometry. 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 standardized 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.
Plastic contamination was detected in all 47 samples, as well as Bisphenol A (BPA), which is still used in many food containers despite health concerns.
To the researchers' knowledge, their study is the first to examine micro and nanoplastics 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 says. "Because these donors have such well-defined histories, our study provides the first clues on potential micro- and nanoplastic exposure sources and routes."
What the results mean for human health is still unclear. However, Kelkar said, it is concerning that these non-biodegradable materials that are present everywhere can enter and accumulate in human tissues.
"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."
Funding for the research came from the Virginia G. Piper Charitable Trust, Plastic Oceans International and the Alzheimer's Association.
ACC said that it’s not clear what impact microplastics may have on people’s health.
“While current scientific research doesn’t support a conclusion that there is a human health concern from microplastics, ACC and its members are helping to lead the way to learn more about the sources and any potential risks that microplastics may pose to people and the environment,” ACC said.