PLASTIC POLLUTION by Richard Sempere: CNRS,  Aix- Marseille Université

1)    Scientific background:

Over the past two decades, the global understanding of plastic pollution has undergone a major transformation. Initially perceived primarily as a problem of visible litter, research has since revealed the complex and pervasive nature of plastic pollution, particularly in the form of microplastics. Scientific progress has expanded knowledge on the sources, environmental pathways, impacts on ecosystems and human health, and the societal responses required to address this challenge. Estimates of total plastic entering the ocean vary significantly depending on data sources and modeling approaches. Early studies, such as those by Jambeck et al. (2015), estimated that between 4.8 and 12.7 million tons of plastic waste enter the ocean annually from mismanaged coastal waste. More recent research, including the work of Weiss et al. (2021), has refined these estimates by incorporating a wider range of sources, such as terrestrial runoff, riverine inputs, and atmospheric deposition. These refined models highlight both the magnitude of plastic pollution and the considerable uncertainty that still exists. Within this broader context, microplastics—defined as plastic particles less than or equal to 5 millimeters in size—constitute a specific and particularly challenging subset of plastic pollution. According to recent assessments, notably Thompson et al. (2024), annual emissions of microplastics into the environment are estimated between 10 and 40 million tons. These microplastics originate from both primary sources (such as microbeads, industrial pellets, and synthetic powders) and secondary sources, resulting from the fragmentation of larger plastic debris during use, waste processing, or environmental degradation.
Microplastics are now widely distributed in all environmental compartments, including the deep sea, coastal sediments, rivers, soils, air, and even polar ice. They are transported over long distances and persist in the environment. Microplastics have been detected in more than 1300 species, including zooplankton, invertebrates, fish, birds, and marine mammals. Evidence from laboratory and field studies demonstrates effects at all levels of biological organization, from cellular stress and tissue inflammation to reduced growth, reproduction, and changes in species behavior. The smallest plastic particles, known as nanoplastics (typically <1 micrometre), are particularly concerning due to their potential to cross biological membranes, interact with cells and tissues, and trigger toxic effects. However, current detection technologies for nanoplastics remain limited, which constrains risk assessment. Biodegradation, when it occurs, depends on polymer type and environmental factors such as temperature, light, oxygen availability, and microbial activity. In many cases, full mineralization is extremely slow or incomplete.

Microplastics/nanoplastics have been found in drinking water, food products (including seafood, salt, fruits, and beverages), and indoor and outdoor air. Recent studies have also detected microplastic particles in human tissues, including lungs, blood, placenta, and digestive systems. While evidence of direct health effects in humans remains limited, laboratory studies suggest potential links to inflammatory responses, oxidative stress, and endocrine disruption. The recent findings have significantly expanded the knowledge base on the sources, fate, and risks associated with micro- and nanoplastics. Additionally, leachates of plastic additives from all manufactured including usual equipment, textiles, tire wear and antifouling paints, are now recognized as major vectors of toxicity. However, challenges remain in establishing dose-response relationships and exposure thresholds due to methodological variability and insufficient long-term data. A precautionary approach is increasingly seen as justified in public health policy.

In response to growing scientific evidence and public concern, a range of policy measures have emerged at national and international levels. These include bans on microbeads in personal care products, regulations on industrial pellet handling, requirements for washing machine filters, and integration of microplastics into regulatory frameworks such as the EU Marine Strategy Framework Directive and REACH regulation. At the global level, microplastics are now part of the negotiations under the draft United Nations Global Plastics Treaty. While many current policies focus on downstream mitigation, scientific consensus increasingly supports upstream measures, including redesign of products, reduction in plastic production, improved waste management, and development of sustainable alternatives. Research into bioplastics and so-called biodegradable materials shows that under real-world conditions, they often fragment similarly to conventional plastics and may retain ecotoxicological risks. Degradation rates depend heavily on polymer type and environmental context. Current evidence suggests that these materials must be critically assessed before being promoted as sustainable alternatives. Addressing plastic pollution calls for interdisciplinary collaboration among chemistry (for polymer characterization and green material design), oceanography and biogeochemistry (for transport and degradation processes), ecotoxicology, engineering, economics, and international legal frameworks. Plastic pollution is not only an environmental issue—it is a systemic problem tied to production and consumption models, requiring innovation, regulation, and global coordination.

2)    Main Contributions of the French Communities through ANR (co)funding (Action plan and France 2030)

A range of recent French-led research initiatives on plastic pollution have contributed major new insights into the nature, transformation, and impacts of micro- and nanoplastics in the environment like in NANOPLASTICS and PEPSEA projects among others. These projects (Table 1), although diverse in their disciplinary approaches, converge on several key scientific priorities. Firstly, advances were made in understanding the environmental fate and transformation of plastics. Fragmentation into micro and nanoplastics, as well as their biofouling, were found to significantly alter transport dynamics in both freshwater and marine environments. Estuaries emerged as critical zones of accumulation and redistribution, where the behavior of particles depends on biofilm development, density shifts, and tidal cycles. The atmosphere has also been identified as a significant, though understudied, compartment in the global plastic cycle. Air-sea exchanges driven by bubble bursting are believed to play a role in the long-range transport of micro- and nanoplastics. Secondly, several projects such as Sedi-PLAST highlighted the importance of sediment archives in reconstructing historical contamination patterns, especially across major rivers like the Seine, Loire and Rhône. These studies produced the first temporal records of microplastic accumulation over decades, offering baseline data for assessing mitigation policies.

At the biological level, significant progress was made in evaluating the interaction between plastics and biota (MicroplastiX, OXOMAR). Some projects such as MycoPLAST focused on fungal communities capable of degrading plastic polymers, while others explored the role of microplastics as vectors for toxic substances and human pathogens. Chronic exposure of fish to biodegradable plastics has also been shown to affect their microbiota, metabolism, and energy balance (EPHEMARE, PLASTOX). The complexity of these interactions underscores the need for long-term studies integrating molecular, ecological, and toxicological perspectives. On the methodological front, substantial innovation occurred. New reference particles mimicking real environmental polyethylene debris were developed for toxicity assays. Protocols to produce micro- and nanoplastics with specific additives and surface modifications were optimized, for instance in ANDROMEDA, improving relevance for risk assessment.

Spectroscopic and chromatographic techniques were refined for smaller particle size detection, down to the sub-micron scale. Modeling tools were enhanced to simulate vertical and horizontal dispersion in coastal systems and to couple oceanic and atmospheric pathways. The biodegradation of conventional and biodegradable plastics under realistic marine conditions remains a key research challenge (SeaBioP). Projects explored how polymer chemistry, particle size, and biofilm formation affect degradation rates and mechanisms. It is now evident that so-called biodegradable plastics may persist longer than expected and may produce secondary pollution if not properly managed.

Several research efforts explicitly engaged with social and economic actors. Citizen science initiatives advanced protocols for participatory monitoring of microplastics in the Mediterranean. Public health risk assessment was also incorporated, especially in the context of artisanal fisheries and pathogen transfer. The development of stable marine foams as filtration systems and advanced oxidation processes for nanoplastic removal represent promising innovations with potential for industrial application (BASEMAN, ANDROMEDA among others). Altogether, these results reinforce the urgency of adopting systemic, interdisciplinary approaches to address plastic pollution. Chemistry, oceanography, microbiology, toxicology, modelling, social sciences, and law must work together to characterize, monitor, and ultimately reduce plastic contamination across the full aquatic continuum. Several projects strengthened the interface between science and society through participatory approaches and awareness tools. Protocols were developed to involve citizens in microplastic monitoring, particularly in the Mediterranean, promoting open and inclusive science. Human health risk assessments were integrated into studies of plastics as vectors of pathogens, especially in artisanal fishing zones. Some projects contributed to the standardization of measurement methods, paving the way for indicators usable in European regulatory frameworks. Innovative low-impact materials (e.g. marine foams, advanced oxidation processes) were tested for real-world applications in water treatment. The production of calibrated reference particles supports toxicity testing relevant for health agencies. Findings on the persistence of so-called biodegradable plastics call for revised eco-labeling and design policies. Finally, the engagement of social sciences offers insight into behaviors and supports the co-construction of public strategies for plastic pollution management.

3)    Research perspectives coming out of the ANR (co)funded projects

Recent multi-institutional research initiatives have outlined a roadmap for advancing plastic pollution science, emphasizing the need for integrated ecological, technological, and regulatory approaches (see BIOMIC project). Future efforts must focus on unraveling the complexity of micro- and nanoplastic pollution across ecosystems, food webs, and human health. A major research frontier involves the fragmentation, degradation, and transformation of plastics in natural environments (as expected in POEM project), particularly in sediments, the water column, and the atmosphere. Understanding these processes is crucial to predicting long-term pollution trends and to designing effective mitigation strategies. Biofouling, UV exposure, sea-air transfer (see recent ATMO-PLASTIC project) microbial activity, and chemical oxidation all influence plastic aging and dispersal. Models must now incorporate vertical transport mechanisms that transfer particles from the surface ocean to deep-sea sediments, as well as air-sea interactions (new project Bubbleplast), which facilitate atmospheric dispersal of microplastics. There is increasing attention on the ecotoxicological impacts of biodegradable plastics, which can fragment and persist in the environment in forms that still pose risks. Their interaction with gut microbiota, effects on metabolic processes, and potential to release chemical additives demand targeted toxicological studies. Likewise, the role of microbial and fungal communities in plastic biodegradation represents a promising frontier for developing bioremediation solutions, yet requires further exploration of degradation pathways under realistic environmental conditions.

A critical and emerging topic is the role of plastics as vectors of pathogens and invasive microorganisms (VECTOPLASTICS). Colonized plastic debris can transport bacteria, viruses, and antibiotic resistance genes across ecosystems. Future research must assess cross-species transmission pathways and potential public health implications, especially in estuaries (PLASTINEST) coastal and aquaculture settings. From an analytical standpoint, improving accelerated aging protocols and detection technologies is essential (New project PLASTIMAR). Advances in spectroscopic and imaging tools have enabled the detection of particles down to the sub-micron scale, and work continues on integrating automated and AI-based identification methods. Simulating environmental weathering in laboratory conditions using UV, mechanical abrasion, or chemical exposure is helping align toxicity tests more closely with field-relevant conditions. These developments are fundamental to the creation of risk indicators and harmonized monitoring tools, which are urgently needed for both research and regulatory purposes.

Research on eco-designed materials and low-impact filtration systems is expanding. New retention processes (like in the new project ECUME) as well as novel materials that are less persistent or easier to degrade—combined with technologies such as bio-inspired marine foams or advanced oxidation processes—open new pathways for sustainable industrial applications and water treatment systems. Their real-world performance and potential unintended effects remain key areas for validation.  Citizen science as the one expected in the A2QUA project is playing an increasingly important role in research. Evolving participatory protocols now extend beyond sample collection to include in-field microplastic and nanoplastic analysis, helping democratize data collection and increase public awareness. These approaches contribute meaningfully to large-scale environmental datasets and promote stronger links between science, policy, and society.

In conclusion, tackling plastic pollution requires coordinated, cross-disciplinary research spanning chemistry, oceanography, microbiology, toxicology, modeling, engineering, plastic cycling and degradation studies such as in AOPNANOP as well as social sciences, and law. It involves tracking particles across environmental compartments, assessing their biological impacts, and integrating findings into practical solutions and robust policy frameworks. The intersection of scientific innovation, public engagement, and regulatory development will be key to building effective strategies for prevention, remediation, and sustainable material use.

4- Structuration of the communities:

France has developed a rich and interdisciplinary academic landscape dedicated to research on plastic pollution across freshwater, marine, terrestrial, and atmospheric environments. This research is supported by major universities and national research organizations that contribute to understanding the sources, fate, impacts, and mitigation of plastics and microplastics. Among the leading academic institutions, Aix-Marseille Université, Sorbonne Université, Université de Bordeaux, and Université de La Rochelle have built strong expertise in marine science, ecotoxicology, analytical chemistry, and ocean modeling. Université de Bretagne Occidentale and Université Bretagne Sud are also key players in the study of plastics in coastal and benthic ecosystems. Further inland, Université de Montpellier, Université de Toulouse, Université Gustave Eiffel, Université du Mans, Université Paris-Est Créteil (UPEC), and Université de Lille are involved in interdisciplinary research on the environmental and societal dimensions of plastic pollution. Their contributions span from human exposure, toxicology, and polymer science to socio-economic assessments and environmental law.
This academic network is complemented by the involvement of major national research bodies such as the CNRS, CEA, INRAE, and IRD, all of which contribute through joint research units or cross-institutional programs. Finally, IFREMER is a major partner in the marine component of plastic research, contributing oceanographic data, long-term monitoring efforts, and scientific coordination in national and European projects. The GDR “Polymères et Plastiques dans l’Environnement”, created by the CNRS, plays a central role in federating over 80 research teams across these institutions.

At the European level, significant support has been provided through research and innovation frameworks, including Horizon 2020 and Horizon Europe, which have funded numerous collaborative projects on plastic pollution. These initiatives address topics such as micro- and nanoplastics, biodegradable materials, risk assessment, and the development of advanced monitoring technologies. Many French laboratories have been active participants and beneficiaries of these programs, contributing their expertise in oceanography, chemistry, ecotoxicology, and environmental engineering to multinational research consortia. In parallel, the Joint Programming Initiative (JPI) Oceans has played a leading role in structuring transnational collaboration by launching thematic calls dedicated to microplastics. Projects such as Andromeda, FACTS, HOTMIC, and microplastiX—all of which included French partners—have produced substantial advances in understanding plastic sources, transport mechanisms, degradation pathways, and ecological impacts. These European efforts have strengthened the integration of French research within a broader continental framework, promoted harmonized methodologies, and supported the development of joint scientific tools and shared data platforms that complement national initiatives. At the national level, most research projects on plastics have been funded by the French National Research Agency (ANR), including those conducted in the framework of European initiatives such as JPI Oceans, where French participation is also supported by ANR.

Bibliography 

Jambeck, J. R., Geyer, R., Wilcox, C., Siegler, T. R., Perryman, M., Andrady, A., Narayan, R., & Law, K. L. (2015). Plastic waste inputs from land into the ocean. Science, 347(6223), 768–771. https://doi.org/10.1126/science.1260352

Weiss, J., van Sebille, E., Lebreton, L., et al. (2021). Plastics in the Indian Ocean – sources, transport, distribution, and impacts. Ocean Science, 18, 1–31. https://doi.org/10.5194/os-18-1-2022

Thompson, R. C., Moore, C. J., vom Saal, F. S., & Swan, S. H. (2024). Accumulation and fragmentation of plastic debris in global environments. Philosophical Transactions of the Royal Society B: Biological Sciences, 364(1526), 1973–1985. https://doi.org/10.1098/rstb.2008.0205