A nationwide survey has revealed the scale of microplastic pollution along Brazil’s beaches, offering one of the most comprehensive coastal snapshots ever produced in the Global South.
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By Guilherme Malafaia
Developed as part of the PhD thesis of Thiarlen Marinho da Luz from the Goiano Federal Institute (IF Goiano) and Federal University of Goiás (UFG), Brazil, Project MICROMar is one of the most comprehensive surveys ever conducted in Brazil on microplastic pollution in marine environments.
The research, conducted between April 2023 and April 2024, collected 4,134 sediment samples from 1,024 beaches across 211 municipalities in all 17 coastal states, covering roughly 7,500 kilometers of shoreline. Their findings revealed that microplastics were present on 69.3% of the beaches, with sharp regional contrasts and several unexpected hotspots.
A Country-Scale Look At Tiny Pollutants
At first glance, the beaches of Brazil – stretching from the Amazon estuary to the southern plains – appear pristine and endless. Yet beneath the sand lies an invisible layer of contamination.
The MICROMar team cataloged 24,549 microplastic particles between 300 micrometers and 5 millimeters, identifying the materials from which these fragments are made, where they cluster, and how risk varies from state to state.
The most common polymers were polyethylene (PE), expanded polystyrene (EPS), and polypropylene (PP) – the same materials used in disposable packaging, foam boxes, and everyday plastics that crumble into smaller fragments when exposed to sunlight, salt, and surf. Polymers such as PVC, PET, and nylon were also detected, hinting at the diverse origins of plastic waste along the coast.
MICROMar also established a national baseline of 27.09 microplastic particles per kilogram (MPs/kg) of sand – the first reference of its kind in Brazil. This benchmark helps distinguish between areas with natural background presence and those affected by excessive contamination. From there, the researchers created maps of pollution hotspots and developed risk indices that integrate both the quantity and the toxicity potential of the detected polymers.
Hotspots
While microplastics were found almost everywhere, specific locations stood out.
Paraná, Sergipe, São Paulo, and Pernambuco registered the highest average concentrations, with municipalities like Pontal do Paraná, Recife, Praia Grande (SP), Aracaju, and Feliz Deserto appearing as repeat hotspots. At the beach level, sites such as Barrancos, the Olinda waterfront, and Guilhermina rose to the top of the national ranking.
What drives these clusters? MICROMar’s modeling suggests a combination of urban pressure and coastal physics.
Beaches near sewage outfalls or urban waterways, those with wide sandy profiles, and those in areas with high plastic use and leakage risk tend to accumulate more particles. In contrast, coarser, rounder sands and certain shoreline types can reduce retention, although these benefits can be negated when human pressures are high. The upshot: local conditions matter, and small infrastructure choices (like how stormwater is routed) can change a beach’s fate.
Beyond Quantity: Why Chemistry Matters
Counting microplastics was just the first step. MICROMar went further by incorporating polymer hazard scores to estimate ecological risk, acknowledging that not all plastics are equally hazardous. Some materials, such as PVC or polystyrene, contain additives, heavy metals, or residual monomers that can leach into the environment or be absorbed by marine organisms.
When these toxicity factors were integrated into the analysis, the researchers found that states like Santa Catarina, Rio Grande do Sul, São Paulo, Maranhão, and Pará ranked higher in ecological risk, even when their particle counts were moderate. This means that a beach with fewer plastics could still be more hazardous, depending on the chemical nature of the polymers present.
Based on the findings, the team reframed the debate: the risk of plastic pollution is not only about the quantity, but also about the type. By focusing on polymer composition and hazard potential, the study provides a more realistic picture of ecological vulnerability – one that captures both visible and invisible threats.
A Living Laboratory for Policy
The project’s integrated approach transforms microplastics from a scientific curiosity into a policy-relevant metric. The 27.09 MPs/kg baseline offers a practical benchmark for municipalities, environmental agencies, and NGOs to identify emerging hotspots and track improvements over time.
This is particularly important in Brazil, where most coastal monitoring has been fragmented or short-term. MICROMar’s unified dataset, spanning from Amapá to Rio Grande do Sul, now provides a national framework for action that can guide both federal programs and local coastal management plans.
Among the recommendations arising from the study are:
- Upgrading sewage and stormwater infrastructure to minimize land-based plastic leakage.
- Reducing high-hazard polymers in packaging and fishing gear through targeted restrictions or replacement programs.
- Integrating microplastic indicators into environmental licensing, beach quality indices, and tourism certifications.
The MICROMar maps could even help shape educational campaigns and citizen science initiatives, enabling communities to recognize their beaches not just as leisure spaces, but as sentinels of ocean health.
From Global Concern to Local Reality
Plastic pollution has long been framed as a global crisis, but MICROMar turns that narrative local. In many of the sampled areas, small rivers, informal dumps, and fish markets were identified as key sources of microplastics. Everyday practices – from washing synthetic clothes to using single-use containers – contribute to what the researchers call a “hidden tide of particles” slowly reshaping Brazil’s shoreline.
“Every grain of sand tells a story,” said Dr. Guilherme Malafaia, coordinator of the MICROMar project and professor at the Goiano Federal Institute (Urutaí, GO, Brazil). “When we zoom in, we see that our beaches are micro-archives of human behavior, reflecting decades of consumption and disposal patterns.”
The project also highlights the urgency of taking action before plastic becomes microscopic. Once fragmented, it is nearly impossible to remove and can be ingested by marine organisms, altering food webs and biogeochemical cycles. In that sense, microplastics are both a symptom and a record of how society treats waste.
A Message of Urgency and Possibility
For Malafaia and his team, the goal was never just to measure contamination, but to empower solutions. “Data must drive change,” he said.
“If we can show where plastics accumulate and which polymers pose the highest risks, then we can act strategically instead of reactively.”
The MICROMar findings carry a message that resonates far beyond Brazil: environmental progress depends on visibility. When pollution is made visible – quantified, mapped, and contextualized – it becomes governable.
The researchers emphasize that microplastics are not an isolated issue, but a symptom of broader systemic failures: fragmented waste management, excessive consumption, and poor coastal planning. Tackling them demands collaboration across levels, from policymakers and port authorities to tourists and local fishermen.
Toward Cleaner Coasts
If there is hope in the MICROMar story, it lies in the fact that most solutions already exist. Improving waste collection, filtering runoff, banning high-risk plastics, and incentivizing the use of circular materials can dramatically reduce inputs. Public awareness also plays a crucial role: when communities understand that their beach litter becomes tomorrow’s microplastics, behavior can shift.
“Brazil’s coast is both a treasure and a thermometer,” noted Thiarlen Marinho da Luz. “By reading what the sand tells us, we can understand not only the health of our oceans, but also our own future on this planet.”
The team now plans to expand the MICROMar network, integrating riverine and estuarine sampling, mangrove sediment analyses, and collaborations with international partners to explore the transboundary movement of microplastics in the South Atlantic.
From Awareness to Action
The MICROMar Project stands as a reminder that the fight against plastic pollution begins with knowledge and accountability. For the first time, Brazil possesses a clear, data-driven map of its microplastic burden — and a scientific foundation for change.
As nations debate a new global plastics treaty, MICROMar shows how regional science can illuminate global challenges. The next step, the team insists, is to ensure that data does not stay confined to journals, but informs policy, education, and everyday decisions.
In the quiet hum of lab instruments and the rhythmic wash of the Brazilian surf, the message is unmistakable: the ocean remembers everything we leave behind – but it can also remember when we start to care.
Featured image: Maria Kray/Pexels.
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About the author: Dr. Guilherme Malafaia is a Brazilian biologist and professor at the Instituto Federal Goiano (IF Goiano), where he coordinates the Laboratory of Applied Environmental Toxicology (LabTox). His research focuses on ecotoxicology, environmental plastic pollution, and the impacts of emerging pollutants on aquatic and terrestrial biota. He also leads the MicroMar Project, the largest survey of microplastic pollution ever conducted in Brazil and the Global South.
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