Twenty years of microplastics pollution research – what have we learned?

Writing in the journal Science, the experts call for worldwide action to tackle all forms of plastic and microplastic debris. National legislation alone is insufficient to address this challenge, and the United Nations’ Plastic Pollution Treaty – which will undergo its fifth round of deliberations in November 2024 – presents a ‘tangible opportunity’ for joined-up international action.

First author Professor Richard Thompson, Head of the International Marine Litter Research Unit at the University of Plymouth: “After 20 years of research there is clear evidence of harmful effects from microplastic pollution on a global scale. That includes physical harm to wildlife, harm to societies and cultures, and a growing evidence base of harm to humans. Added to that is the fact that microplastics are persistent contaminants, and once in the environment they are virtually impossible to remove. There are still unknowns, but during the 20 years since our first study the amount of plastic in our oceans has increased by around 50%, only further emphasising the pressing need for action.”

Better calculation of ecological risks

Microplastics have been found on every corner of the planet. In the food and drink we consume, in the human body, and in more than 1,300 aquatic and terrestrial species across a wide variety of ecosystems. To obtain a clearer picture of the ecological risks of microplastics, the group of Bart Koelmans, Professor of Aquatic Ecology and Water Quality at Wageningen University & Research and co-author of the study, has developed improved measurement and calculation methods. For example, which species in an ecosystem are supposedly affected by microplastics, how much, and will their numbers cross a critical boundary as a result?

“What I consider as a big step forward is that we are now able to actually calculate the ecological risks,” Koelmans explains. “To achieve this, we initially needed to find a way to address the vast variety in microplastic particles, because these differ widely in sizes, shapes and composition. In the past few years, we took this further and developed calculation tools that help to better determine what percentage of a species in an ecosystem is affected by microplastics. Currently, we are developing similar methods to estimate the risks for humans.” Knowing where, when, and why these risks arise is a starting point for providing policymakers with a course of action and for designing solutions.

20 years of microplastic research

The article in Science was written to mark the 20^th anniversary of the first ever study – also published in Science – to coin the term ‘microplastics’ to describe the microscopic fragments of plastics in our oceans. The new publication was co-authored by experts in marine biology, sustainability, environmental psychology, global plastics policy, and risk assessment, from University of Plymouth, University of Bangor (UK), Earth Action (Switzerland), University of Vienna (Austria); University of Wollongong (Australia), and Wageningen University & Research.

Since the publication of the first study in 2004, an estimated 7,000 research studies have been conducted on microplastics, providing considerable evidence in their sources and impacts as well as potential solutions.