Microplastics are everywhere. We drink them in our water, eat them in our food, breathe them in the air, leading to – so we’re told – alarming levels of plastic building up in our tissues.
So it was somewhat of a shock this week when The Guardian published a “bombshell” article suggesting that scientists may be overstating health concerns. Award-winning journalist Damian Carrington, a champion of environmental issues, accepted he had warned of the dangers himself, but said there was growing concern about the technology being used to detect small pieces of plastic in the body.
The article followed a recent letter published in Nature’s Medicine which questioned the analytical techniques used to detect microplastics in human tissue, warning that they lack controls and validation. One of the signatories, Dr Dusan Materic, from the Helmholtz Center for Environmental Research in Germany, argued that body fat can give a false positive for polyethylene and said the obesity epidemic could be behind the perceived increase in body plastic.
Most studies “not scientifically convincing”
Another signatory, Dr. Fazel Monikh of the University of Padua, Italy, who has spent a decade working on the detection of nanomaterials in biological samples, says he has never encountered the types of microplastics reported in the recent studies. “When particulate materials enter a living organism, including the human body, they undergo biotransformation,” he tells The Telegraph.
“Even assuming the highly unlikely scenario where an intact particle reaches a protected compartment such as the brain and is then successfully detected, it would not retain the appearance shown in most of the reported data.
“For these reasons, most of the presented results and their interpretation are not scientifically convincing to me, nor to my colleagues who are experts in this field.”
Microplastics were first detected in the human body in 2018, when Austrian scientists analyzed stool samples from people in eight countries – including the UK – and found that each contained tiny particles. Such research is not in doubt and there is good evidence that humans ingest tens of thousands of plastic particles each year. The point of contention is whether they become embedded in tissues, causing long-term damage.
The problem seems to lie with smaller versions of microplastics, known as nanoplastics.
Officially, microplastics are no larger than 5 mm in size (the size of a grain of rice or smaller), while nanoplastics are 1 nm to 1,000 nm in size (as small as bacteria) and are much harder to detect. In recent years, studies have claimed to have found these tiny particles in nearly every human organ and tissue, including the lungs, liver, kidneys, heart, brain, placenta, testicles, bone marrow and blood.
It is feared that these tiny intruders carry toxic chemicals that cause inflammation and cell damage, as well as disrupting hormones, harming gut microbes, lowering IQ, decreasing fertility and increasing the risk of cardiovascular disease, cancer, heart attacks and stroke. The paper that sparked the recent Nature’s Medicine The rejection letter claimed to have found microplastics and nanoplastics in the brain, which the scientists behind it linked to dementia.
Such studies have sparked a wave of environmental anxiety, with people switching to plastic-free tea bags and ditching water bottles, kitchen sponges, polyethylene chopping boards and non-stick pans.
Methodological concerns
But there are concerns that because microplastics are so widespread in the environment, it is difficult to detect whether they actually enter human tissue or whether samples are merely contaminated during the collection and analysis process. Laboratory tests should include “controls”—control samples of clean water or inert material processed as real samples to detect contamination—but many studies do not.
Fay Couceiro, professor of environmental pollution at the University of Portsmouth, says: “I don’t think there’s any doubt that there are microplastics in us – they’re everywhere and we breathe them and eat them every day, so it’s inevitable that they’re in us.
“I think the question is more about where they are stored in the body and how much there is.
“Some studies—especially human-based ones—do not follow the full standard methodologies used in environmental sampling around blanks, replications, and recovery checks.”
With large microplastics, scientists can easily observe the particles under a microscope and then shoot a laser at them to see if they are plastic. But with nanoplastics, scientists have to burn the particle and measure the gases emitted, which is less reliable and still in its infancy as a technique.
This lack of testing confidence has made researchers more skeptical of the more alarmist findings. An abstract presented at the European Society of Human Reproduction and Embryology last year showing microplastics in human reproductive fluids was met with raised eyebrows among scientists.
“Many previous scary-sounding headlines about microplastics in blood and food turned out to be measurement errors,” warns Oliver Jones, professor of chemistry at RMIT University, Melbourne, referring to reports that preceded last year’s findings.
Also, separate claims that microplastics were found in human blood in 2022 were criticized by a US chemist as “consistent with accidental or accidental contamination”, in a letter to the journal Environmental International.
Even Dr. Philipp Schwabl of the Medical University of Vienna, who discovered the initial evidence of microplastics in the human body, is not sure about their health impact. “The question of how harmful these small plastic foreign bodies really are remains open to me, and thus constitutes a crucial area of environmental biology that remains to be scientifically elucidated,” he says.
“It’s still a serious problem”
However, despite testing problems, many experts are still convinced that microplastics cause harm.
Professor Philip Landrigan, a pediatrician and epidemiologist at Boston College in the US, led a recent review of microplastics for the Lancet and says people should not dismiss the dangers. “The Guardian article is correct in pointing out that there is work to be done in refining, standardizing and harmonizing analytical techniques for examining microplastics in tissue samples,” he says.
“There is a particular need to distinguish microplastics from lipids [fats]. But the Guardian is wrong to suggest that this whole area of science is rubbish.
“The presence of microplastics in the human body must be taken seriously, even if we do not yet know all the ways in which they can harm health. They cannot be eliminated.”
The Medical University of Vienna recently developed a new imaging technique that can detect plastics without the need to burn samples. They say it reduces the risk of contamination and allows scientists to find direct correlations between tissue samples and disease.
And Dr. Matthew Campen of the University of New Mexico, lead author of the brain study that was challenged Nature’s Medicinesaid his team hosted a conference on microplastics in recent days where “compelling” new evidence of particles in cerebrospinal fluid was presented. “Our paper is actually very clear about where the uncertainties lie and how they can affect the interpretation of the results,” he added. “We are 100% confident that the nanoplastics are in the brain.”
Prof. Lukas Kenner, deputy director of the Department of Pathology at the Medical University of Vienna, says: “The concerns raised are understandable, but a blanket rejection of the entire body of evidence is not scientifically justified.
“While early studies certainly had methodological limitations, the field has advanced rapidly.
“There is now good evidence that microplastics can enter and accumulate in the human body, and there is increasing experimental evidence that they are biologically active rather than inert.”
For now, it appears the scientific community is divided on the true impact of microplastics, and it could be several years before a consensus is reached on the damage. The debate over the extent to which they enter and remain in human bodies will be a key part of these discussions.
While some fear that plastic could be the modern equivalent of asbestos, lead or tobacco, it is possible that the particles are processed or expelled by the body before causing long-term damage.
Professor Christian Dunn, an expert on microplastic pollution at Bangor University in Wales, says: “When it comes to nanoplastics, I think we’re still pushing the limits of what we can reliably detect.
“How much of this plastic enters and accumulates in our organs, and the damage it causes us, is still being scientifically discovered.”
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