Exclusive: Some scientists say many detections are most likely error, with one high-profile study called a ‘joke’

Summary: we could have considerable extra time to figure out how to not pollute everything and ourselves with microplastic. Systematic flaws in several microplastic studies point towards human body fat mimicking the signature of polyethylene, leading to serious overestimation of how far microplastic can penetrate:

“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.” Materić and his colleagues suggested rising obesity levels could be an alternative explanation for the trend reported in the study.”

  • perestroika@slrpnk.netOPMEnglish
    9·
    23 days ago

    A longer excerpt that sheds light on the measurement problems which research into microplastics is facing.

    A key way of measuring the mass of MNPs in a sample is, perhaps counterintuitively, vaporising it, then capturing the fumes. But this method, dubbed Py-GC-MS, has come under particular criticism. “[It] is not currently a suitable technique for identifying polyethylene or PVC due to persistent interferences,” concluded a January 2025 study led by Dr Cassandra Rauert, an environmental chemist at the University of Queensland in Australia.

    “I do think it is a problem in the entire field,” Rauert told the Guardian. “I think a lot of the concentrations [of MNPs] that are being reported are completely unrealistic.”

    “This isn’t a dig at [other scientists],” she added. “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.” She said the failure to employ normal quality control checks was “a bit crazy”.

    Py-GC-MS begins by pyrolysing the sample – heating it until it vaporises. The fumes are then passed through the tubes of a gas chromatograph, which separates smaller molecules from large ones. Last, a mass spectrometer uses the weights of different molecules to identify them.

    The problem is that some small molecules in the fumes derived from polyethylene and PVC can also be produced from fats in human tissue. Human samples are “digested” with chemicals to remove tissue before analysis, but if some remains the result can be false positives for MNPs. Rauert’s paper lists 18 studies that did not include consideration of the risk of such false positives.

    I can only conclude that a better measurement method is needed. Either the vaporization of samples or the chemical digestion will have to be replaced - but what that method will be, I can’t guess.