Many scientists say microplastics pose a real, if often subtle, threat to human health. A study this week could provide a vital clue to how this damage occurs.
Researchers at Columbia University and others have closely studied the behavior of microplastics in water. They found that when plastic is broken into tiny fragments and surrounded by water, it can easily produce highly reactive molecules. Although additional studies are still needed to understand the exact health impacts of microplastics, the team’s work challenges the assumption that plastic is always chemically passive, the authors say.
“Our results challenge the dominant paradigm of plastic inertia (and) identify a perhaps overlooked mechanism for the adverse health and environmental effects of microplastics,” they wrote in their paper published Wednesday in the journal Nature.
Not so inert
Microplastics are any piece of plastic smaller than 5 millimeters. Over the years, scientists have increasingly sounded the alarm about the likely dangers of microplastics for humans and other animals.
We know that plastics typically contain chemicals that can mimic and possibly disrupt the functioning of certain natural hormones. Some research also suggests that microplastics can directly harm our bodies, but data on these potential risks is more limited.
One of the reasons why plastics are so widely used in society is that they are meant to be chemically inert under normal circumstances. The researchers’ experiments, however, indicate that this hypothesis no longer holds true once plastics are broken down into tiny pieces that can enter our bodies. Specifically, they discovered that microplastics are capable of spontaneously generating unstable molecules called free radicals when in the presence of water.
“As plastic fragments into smaller and smaller particles, its surface area increases enormously,” lead study author Wei Min, a professor of chemistry and biomedical engineering at Columbia, said in a Columbia news release. “Then, microplastics modify the water around them, generating high-energy reactive radicals that most likely contribute to the biological damage we see in animals and potentially in humans following exposure to microplastics.”
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Obviously, our bodies are full of water, so it’s entirely reasonable to think that microplastics can also create these radicals inside us. We could also be exposed to these molecules by drinking bottled water, the researchers speculate. Such radicals could then explain at least some of the harmful bodily changes that scientists have associated with microplastics, such as inflammation, immune dysfunction, and altered metabolism.
At the same time, scientists are still trying to quantify the health risks of microplastics, which can be influenced by other factors like age. How much plastic exposure per day or per year is necessary to significantly increase the risks of a certain health problem, for example, and do these risks differ depending on exactly where plastics end up in the body? As important as these and other questions are, microplastics are unlikely to be completely harmless to humans (and there is strong evidence that they are particularly harmful to the marine environment).
This study should therefore help scientists better understand the dangers of microplastics, and the researchers hope that it could even lead to better plastic production methods that could reduce the risk of free radical generation.
Gn Health
