Plastic pellets, bio-beads and other microplastics are polluting coastlines around the world, with new research showing sharp regional differences in the types and concentrations of plastic found.
The findings come from a study by the University of Portsmouth using data from the Big Microplastic Survey (BMS) – one of the largest citizen science projects of its kind – which analysed 1,089 surveys carried out by volunteers across 39 countries between 2018 and 2024. The study, published in Environmental Monitoring and Assessment, examined nearly 59,000 pieces of plastic to map global patterns of coastal pollution.
This is certainly not the first such study to reveal the widespread nature of microplastic contamination, but it does appear significant in its scale and scope, while also demonstrating the feasibility and limits of citizen science as a global monitoring tool.
The research revealed that nurdles – pre-production plastic pellets – were the most common type of plastic recorded. The Netherlands reported the highest counts, with levels 14 times greater than the next worst-affected country – primarily the result of a shipping container disaster. Bio-beads, which are widely used in wastewater treatment, were also heavily concentrated in the Netherlands and Honduras, with Britain ranking third, based on average counts per sample.
In contrast, secondary plastics – fragments that break down from larger items – were more commonly found in Kenya and Honduras. Expanded polystyrene was particularly prevalent in Thailand, Indonesia and Portugal. Across all countries, white plastics dominated, followed by clear or opaque, blue and green.
Alongside the pollution data, the study demonstrated how citizen science can work on a global scale. There were more than 1,000 registrations to participate in the project from 66 countries, with Britain, the United States and Australia providing the highest numbers.
However, fewer than one in five registrants went on to submit data, underlining the challenges of sustaining volunteer engagement. Where projects did succeed, they were often driven by non-governmental organisations, which proved to be the most effective contributors and were frequently responsible for the bulk of surveys within their regions.
Lead author Dr David Jones from the University of Portsmouth said: “Our results show that plastic pollution is not just a local problem, it’s a global crisis, with different regions facing different challenges. Several thousand volunteers have taken part in the Big Microplastic Survey, which demonstrates the power of citizen science to gather data on a scale that traditional methods alone could never achieve.”
The research highlights the growing importance of citizen science in supporting international efforts to tackle plastic pollution. In 2022, the United Nations Environment Assembly agreed to a legally binding treaty to end plastic pollution, which calls on member states to improve monitoring and reporting. The treaty is still under negotiation.
Dr Michelle Hale, Head of School of the Environment and Life Sciences at the University of Portsmouth, added: “While there are limitations to volunteer-collected data, citizen science can fill critical gaps, particularly in regions where resources for environmental monitoring are limited. It also helps build community engagement – a vital step in tackling plastic pollution at its source.”
The study concludes that combining citizen science with traditional scientific methods could offer the most effective approach to tracking the spread of microplastics and shaping policies to reduce them.
The University of Portsmouth is home to the Revolution Plastics Institute which is dedicated to finding solutions that address plastic pollution and generating a globally-relevant community of plastics researchers.
The Institute aims to urgently confront the global plastics crisis through inclusive, solutions-focused research and innovation to support the transition to a sustainable plastics future. Projects span across all disciplines combining creativity, research and innovation to address the impact of plastic.
