Plastic pollution is found in all habitats on Earth, and is considered a major environmental hazard. The EU is committed to tackling plastic pollution through its plastics strategy, adopted in 2018 as part of its circular economy action plan.
While definitions vary, plastic in the environment is split by size into macroplastic particles (pieces of >5 mm across) and smaller microplastic particles. While there is no formal definition of plastic particles smaller than this, by convention, those measuring less than 1 micron (<0.001mm) across are called nanoplastic particles. These may have different properties to larger pieces of plastic, and we require additional and specific methods to reliably detect and characterise them (as comprehensively reviewed in the Future Briefing: “Nanoplastics: state of knowledge and environmental and human health impacts”, produced for the European Commission by Science for Environment Policy in 2023).
Due to these prevailing difficulties in detection and standardised measurement, nanoplastic cannot currently be addressed by EU policy in the same way as larger plastic pieces. Unless explicitly stated otherwise, nanoplastic is addressed as a fraction of microplastic by EU policy documents, including the aforementioned plastics strategy and its annexes (which include a list of “actions to curb microplastics pollution”).
While nanoplastics are sometimes specifically manufactured and incorporated in products, they are far more commonly generated as larger plastics break down. This includes incidental particles from tyre wear or washing of synthetic fabrics, as well as decomposition of plastic waste through abrasion or exposure to sunlight, by which it degrades into smaller and smaller pieces.
Due to their size, nanoplastics are difficult to collect and analyse from ocean water samples. The presence of these particles in ocean water has been confirmed for some time but has not been reliably quantified. Estimates of total ocean pollution to date typically do not include any contribution from nanoplastic – although as the size of plastic in the ocean skews towards smaller particles over time, we suspect that nanoplastic particles could be a globally important environmental contaminant.
A team of researchers from the Netherlands and Germany set out to address this knowledge gap, with financial support from the European Research Council. They took samples from 12 sites across the North Atlantic, ranging from the subtropical gyre to the southern North Sea. At each site they took samples at multiple depths – one within 10 metres of the surface, one within 30 metres of the sea floor, and in deeper waters one at an intermediate depth of 1 kilometre. When processing the samples, they analysed particles smaller than 0.001 mm using a mass spectrometry technique that provides data on the type and quantity of plastic.
The researchers found significant quantities of nanoplastic at all locations and at all depths. The average concentration of plastic was highest in the mixed layer (near the surface) at 18.1 milligrammes per cubic meter (mg/m3). This fell to 10.9 mg/m3 in the intermediate layer and again to 5.5 mg/m3 in the bottom layer. (Due to the depth constraints at the coastal shelf locations, these were only included in the analysis for the mixed layer calculations.)
In the mixed layer, nanoplastic concentration was highest in coastal shelf locations, at 25.0 mg/m3. This is consistent with the observation that nanoplastics can enter the ocean from the land in the same ways as other plastics, such as through rivers or directly from the coast. The researchers note that nanoplastic can also be transported from land to ocean over long distances via the air.
The vast majority of the nanoplastic detected was of three types: polyethylene terephthalate (PET), polystyrene (PS), and polyvinyl chloride (PVC). However, these types were unevenly distributed across depths and locations (likely as a result of how different plastics float, sink, and fragment, and connected to their initial sources and routes into the ocean, the authors speculate). At intermediate depth, locations within the sub-tropical gyre contained 2.5 times the concentration of PET compared to locations outside the gyre, while PVC and PS showed no significant difference. PET concentrations also remained similar at all depths, while concentrations of the other plastic types decreased markedly, with minimal levels detected in the bottom layer.
The concentrations of nanoplastic found in the mixed layer in the open ocean locations (away from the coastal shelf) were substantially higher than those reported or modelled for macro- and microplastic in similar areas, say the researchers. They used their figures from the stations within the gyre and in the open ocean outside the gyre to estimate the total mass of nanoplastic particles in the mixed layer of the North Atlantic (between latitudes 8.5° N and 55° N). They arrived at estimates of 15.20 megatonnes (Mt) of plastic using the figures from inside the gyre and 11.73 Mt using figures from outside it. They contrast this with a recent study estimating the total mass of macro and microplastic in the mixed layer of the North Atlantic at 0.31 Mt within the ‘gyre’ and 0.05 Mt outside it.
The researchers highlight that their results suggest that nanoplastic, previously excluded from such estimates, may contribute significantly more to the total mass of plastic in the ocean than macro and microplastic combined. They argue that there is an urgent need to conduct further research to better understand the dynamics of ocean nanoplastic generation, distribution, and ultimate effects.
Source:
Ten Hietbrink, S., Materić, D., Holzinger, R., Groeskamp, S., and Niemann, H. (2025) Nanoplastic concentrations across the North Atlantic. Nature 643, 412–416. https://doi.org/10.1038/s41586-025-09218-1
References:
Science for Environment Policy (2023) Nanoplastics: state of knowledge and environmental and human health impacts. Future Brief 27. Brief produced for the European Commission DG Environment by the Science Communication Unit, UWE Bristol. https://ec.europa.eu/scienceenvironment-policy