Several researchers and interested parties have raised doubts about published, peer-reviewed studies on the impact of microplastics on human health, the Guardian reported.

What’s happening?

It’s often said that “microplastics” are “everywhere,” and “everywhere” certainly includes the news cycle.

Studies about the environmental and biological impacts of microplastic exposure appeared at a rapid clip after they were first identified in 2004, all pointing to an insidious, worsening problem. 

The Guardian routinely covers new research into microplastics, but on Jan. 13, the outlet reported that some researchers had challenged a handful of prominent microplastics studies.

Unlike the outlet’s typical coverage of microplastics research, the article was not based on a study, nor were the “doubts” raised by researchers part of any formal research effort. Some of the article’s paraphrased excerpts were arguably vague.

“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,” the article stated.

The Guardian “identified seven studies” that other researchers had challenged, which readers could interpret as an indicator of inherently or obviously flawed research. 

However, that part of the process — often known as “Letters to the Editor” — is “an ineffaceable part” of published research, one journal article noted in 2023. Although challenges are indexed like studies, post-publication objections are not peer-reviewed.

The Guardian quoted one critique by Dr. Dušan Materić, an expert on microplastics and nanoplastics. Materić took issue with the methodology of a study into microplastics infiltrating the human brain.

“The brain microplastic paper is a joke. Fat is known to make false-positives for polyethylene. The brain has [approximately] 60% fat,” he said in a February LinkedIn post. 

Why is this concerning?

Although scientific understanding of microplastics is still in its infancy, challenges to research are not exclusive to the topic. Researchers also regularly identify study limitations to avoid overgeneralizations and to account for potential gaps in understanding. Still, reams of peer-reviewed research have shown microplastics pose risks to the environment, wildlife, and human health.

Microplastics have been found in the most remote corners of the planet — where they are certainly not masquerading as “fat” — and they’ve been linked to a battery of adverse health effects in people and animals.

While Materić’s critique was specific to a single study and its setup, several “doubts” voiced in the article were unrelated to study findings.

Environmental chemist Dr. Cassandra Rauert acknowledged microplastics were a concern and fretted that expensive, untested treatments to “purge” microplastics from the blood were driven by alarming studies.  

“The responsibility [for scientists] is to report robust science so you are not unnecessarily scaring the general population,” Rauert said, describing panicked calls from a worried public.

According to the Guardian, former Dow Chemicals Company chemist Roger Kuhlman called objections to seven studies out of thousands a “bombshell.”

“This is really forcing us to re-evaluate everything we think we know about microplastics in the body. Which, it turns out, is really not very much. Many researchers are making extraordinary claims, but not providing even ordinary evidence,” Kuhlman asserted, not providing specifics.

Dow has come up more than once in the context of microplastic pollution caused by nurdles, and the company argued as recently as 2023 that the risks of microplastics to the environment and human health “[have] not been demonstrated.”

What’s being done about it?

In October, the International Science Council reviewed 7,000 studies on microplastics.

“The scientific evidence is now more than sufficient: collective global action is urgently needed to tackle microplastics – and the problem has never been more pressing,” reviewers concluded.

Plastic pollution and the risks of microplastics are well-documented — using less plastic is one simple way to reduce your household’s direct exposure.

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