Have scientists been wrong about microplastics in our bodies all along? The Guardian has reported on ‘bombshell’ concerns that contamination and false positives could have led studies to overestimate their findings, sparking fears of disproportionate countermeasures.
While The Guardian emphasizes that there is “no suggestion of malpractice”, scientists have expressed concerns that researchers – some of them with “limited analytical expertise” – have failed to carry out routine scientific checks during their studies and rushed to publish skewed results.
Dr Frederic Béen, assistant professor in Vrije Universiteit Amsterdam’s Chemistry for Environment & Health research group, observes that “quite a lot of papers” have not followed “very standard” laboratory practices, such as repeating measurements, preventing background contamination, and accounting for blanks.
In one example, Dr Dušan Materić from the Helmholtz Centre for Environmental Research’s Department of Environmental Analytical Chemistry has challenged the results of a study in which scientists claimed to identify 10,000 nanoplastic particles per litre of bottled water. He argues that insufficient quality control and failure to account for contamination from the sample handling procedure – allegations that the original researchers have denied – leave the final figure “fundamentally unreliable”.
Another study sought to examine the presence of micro- and nanoplastics in brain tissue. Other scientists critiqued the paper’s “methodological challenges, such as limited contamination controls and lack of validation steps, which may affect the reliability of the reported concentrations.”
Materić went so far as to describe this study as a “joke”, adding: “Fat is known to make false-positives for polyethylene […] The brain has [approximately] 60% fat, and the liver has [approximately] 5%, so that is why there are [approximately] 10 times more “plastics” in the brain.”
Dr Cassandra Rauert, an environmental chemist at the University of Queensland, considers “a lot” of the reported concentrations of plastic particles in the body to be “completely unrealistic.” Based on “what we know about actual exposure in our everyday lives”, she believes that it is “not biologically plausible” for particles between 3 and 30 micrometres in mass to enter the bloodstream.
“It’s really the nano-size plastic particles that can cross biological barriers and that we are expecting inside humans,” she continues. “But the current instruments we have cannot detect nano-size particles.”
She clarifies that her opinion “isn’t a dig” at other scientists: “They use these techniques because we haven’t got anything better available to us. But a lot of studies that we’ve seen coming out use the technique without really fully understanding the data that it’s giving you.”
Similarly, Prof Marja Lamoree, professor of Analytical Chemistry for Environment and Health at Vrije Universiteit Amsterdam, indicates that some studies are not conducted by experts in analytical chemistry, and that few existing laboratories are not suitable for this kind of research. For example, she highlights the danger of taking solid tissue samples in operating theatres “full of plastic.”
Responding to the backlash, Prof Matthew Campen – director of the University of New Mexico’s Center for Metals in Biology & Medicine, and senior author of the study on brain tissue – counters that scientists are in an “early period” of understanding the health implications of micro- and nanoplastics.
“There is no recipe book for how to do this,” he told The Guardian. “Most of the criticism aimed at the body of work to date (i.e. from our lab and others) has been conjectural and not buffeted by actual data.
“We have acknowledged the numerous opportunities for improvement and refinement and are trying to spend our finite resources in generating better assays and data, rather than continually engaging in a dialogue.”
Marja Lamoree is also the senior author of an initial study claiming to detect microplastics in human blood. While she maintains that her research correctly identified plastic particles, she allows for variation in the estimated amount of plastic present, acknowledging that the study of micro- and nanoplastics in the human body is “still a super-immature field”.
Even so, scientists are concerned that inaccurate findings could lead to the introduction of disproportionate policies and regulations, or fuel efforts to lobby against restrictions on plastic pollution.
Yet Béen acknowledges that analytical techniques are improving and comments: “I think there is less and less doubt about the fact that micro- and nanoplastics are there in tissues. The challenge is still knowing exactly how many or how much. But I think we’re narrowing down this uncertainty more and more.”
While Rauert states that scientists “definitely want to know what happens” when the human body is exposed to micro- and nanoplastics and will “keep working at it”, Lamoree concludes that scientists should foster “much more open communication” as they work towards a more definitive answer.
The article comes after previous research from the University of Leicester and the University of Cape Town posited that brightly coloured plastics break down into microplastics at a faster rate than those in plainer colours. The findings used two complementary studies to demonstrate that, depending on the colourant used to formulate them, plastics of the same composition could degrade at different rates.
In the lead-up to INC-5.2, WWF and the University of Birmingham doubled down on the importance of solidifying a Global Plastics Treaty by connecting micro- and nanoplastics to various environmental and human health impacts, including disrupted food production, cancer, and infertility.
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