Scary Findings on Microplastics in Our Bodies May Be Flawed. That’s Good—and Bad. |
Plastic pollution on a beach in Sri Lanka.Thilina Kaluthotage/NurPhotos/AP
This story was originally published by the Guardian and is reproduced here as part of the Climate Desk collaboration.
High-profile studies reporting the presence of microplastics throughout the human body have been thrown into doubt by scientists who say the discoveries are probably the result of contamination and false positives. One chemist called the concerns “a bombshell.”
Studies claiming to have revealed micro- and nanoplastics in the brain, testes, placentas, arteries, and elsewhere were reported by media across the world, including the Guardian and Mother Jones. There is no doubt that plastic pollution of the natural world is ubiquitous, and present in the food and drink we consume and the air we breathe. But the health damage potentially caused by microplastics and the chemicals they contain is unclear, and an explosion of research has taken off in this area in recent years.
However, micro- and nanoplastic particles are tiny and at the limit of today’s analytical techniques, especially in human tissue. There is no suggestion of malpractice, but researchers told the Guardian of their concern that the race to publish results, in some cases by groups with limited analytical expertise, has led to rushed results and routine scientific checks sometimes being overlooked.
One scientist estimates there are serious doubts over “more than half of the very high impact papers” on microplastics in biological tissue.
The Guardian has identified seven studies that have been challenged by researchers publishing criticism in the respective journals, while a recent analysis listed 18 studies that it said had not considered that some human tissue can produce measurements easily confused with the signal given by common plastics.
There is an increasing international focus on the need to control plastic pollution but faulty evidence on the level of microplastics in humans could lead to misguided regulations and policies, which is dangerous, researchers say. It could also help lobbyists for the plastics industry to dismiss real concerns by claiming they are unfounded. While researchers say analytical techniques are improving rapidly, the doubts over recent high-profile studies also raise the questions of what is really known today and how concerned people should be about microplastics in their bodies.
“Levels of microplastics in human brains may be rapidly rising” was the shocking headline reporting a widely covered study in February. The analysis, published in a top-tier journal and covered by the Guardian, said there was a rising trend in micro- and nanoplastics (MNPs) in brain tissue from dozens of postmortems carried out between 1997 and 2024.
However, by November, the study had been challenged by a group of scientists with the publication of a “Matters arising” letter in the journal. In the formal, diplomatic language of scientific publishing, the scientists said: “The study as reported appears to face methodological challenges, such as limited contamination controls and lack of validation steps, which may affect the reliability of the reported concentrations.”
One of the team behind the letter was