New Study Finds High Concentrations of Nanoplastics in Ocean Water

Plastic pollution of the oceans is a well-known and researched field of study, but most attention has been given to macroplastics and microplastics. Microplastics have been proven to attract and carry pollutants in the water, release chemicals into the water, and pose health risks to marine species that mistake them for food (NOAA). In contrast, scientific knowledge on the prevalence and effects of nanoplastics in the ocean has been extremely limited until recent years. However, a new study conducted in summer 2025 identified a large presence of nanoplastics, plastic particles even smaller than microplastics, in the ocean (Hietbrink et al., 2025). 

The study highlights that the issue of ocean pollution may be even more severe than scientists previously thought. Sophie ten Hietbrink, a lead author of the study, stated that while the research team was expecting to discover nanoplastics in the water, the sheer quantity could not have been predicted (New York Times). The study found an average concentration of nanoplastics of 25 milligrams per cubic meter of water, with higher concentrations closer to the surface level (Hietbrink et al., 2025). 

In total, the mass of nanoplastics was estimated to be 27 million tons in the mixed layer of the temperate to subtropical North Atlantic ocean alone. This is equal to, if not more than, the estimates for macroplastics and microplastics in the entire Atlantic ocean. Researchers now believe that nanoplastics comprise the majority of ocean plastic pollution (Hietbrink et al., 2025). 

While these results may seem insignificant at first glance, the presence of nanoplastics poses an intensified risk to marine life. Research has shown that nanoplastics may be even more dangerous than microplastics due to their smaller size and higher abundance. Nanoplastics are small enough to permeate through biological membranes and pass through the trophic levels, leading to potential health risks both in animals and humans (Sharma et al., 2022). 

Studies have shown that ingestion of nanoplastics triggered stress defenses and impeded growth and reproduction in marine species (Lie et al., 2019). In addition, nanoplastics have the capacity to absorb and leach existing environmental pollutants and plasticisers, as well as to enhance the absorption of toxic chemicals into the atmosphere (Wang et al., 2016). While the specific human health risks associated with nanoplastics remain under-studied, they are likely to pose a similar danger to human health, especially in high quantities (PMC). 

The results of this groundbreaking study highlight the need for better plastic waste management to curb the toxic effects of nanoplastics. As of now, annual production of plastics exceeds 400 million tons. Nearly 80 percent of them end up in landfills or the natural environment, and up to four million tons enter the ocean each year (Science Advances). 

In addition to system-wide waste management improvements, individual consumers can take steps to reduce their contribution to plastic pollution. By reducing use of single-use plastics, properly recycling, avoiding products containing microbeads, and supporting legislation to curb plastic production and waste, individuals can help address the plastic pollution problem (Oceanic Society).