Are our bodies really full of microplastics?

Doubts over whether plastic particles have infiltrated human tissue have grown, with one high-profile study called a 'joke'

- Damian Carrington

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".

While there is no suggestion of malpractice, 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.

Faulty evidence on the level of microplastics in humans could lead to misguided regulations and policies, researchers say. It could also help plastics industry lobbyists to dismiss concerns by claiming they are unfounded.

"Levels of microplastics in human brains may be rapidly rising" was the headline reporting a study last February. The analysis, published in the journal Nature Medicine and covered by the Guardian, said there was a rising trend in microand nanoplastics (MNPs) in brain tissue from dozens of postmortems carried out between 1997 and 2024.

By November, though, the study had been challenged by a group of scientists with the publication of a letter in the journal: "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 blunt. "The brain microplastic paper is a joke," said Dr Dušan Materić, at the Helmholtz Centre for Environmental Research in Germany. "Fat is known to make false-positives for polyethylene. The brain has [approximately] 60% fat."