Everyday plastic products, including water bottles, disposable cups, and packaging, can break down over time into tiny fragments known as nanoplastics. These particles are invisible to the naked eye and can become airborne, raising concerns about their potential to reach deep into the lungs when inhaled.
However, most research on the health effects of nanoplastics has focused on polystyrene (PS), partly because particles made from this material are readily available for laboratory studies. Much less has been known about how polyethylene (PE) and polypropylene (PP), two of the most widely used plastics in everyday life, affect the lungs.
A research team led by Dr. Jinyoung Jeong at the Environmental Diseases Research Center of the Korea Research Institute of Bioscience and Biotechnology (KRIBB), in collaboration with Professor Wan-Seob Cho at Dong-A University, has compared the lung toxicity of PE and PP nanoplastics and identified molecular pathways involved in the resulting inflammatory responses.
The researchers prepared PE and PP nanoparticles and compared their effects with those of diesel exhaust particles. Using a mouse model in which particles were delivered directly into the trachea, they evaluated lung inflammation and investigated the biological processes underlying the response.
Both types of nanoplastics caused acute lung inflammation. Importantly, their relative inflammatory potency depended on how the particle dose was measured.
When compared by mass, PE nanoplastics produced an inflammatory response at least as strong as that of diesel exhaust particles. When the researchers compared doses based on particle surface area, both PE and PP nanoplastics showed greater inflammatory potential than diesel exhaust particles.
The team also examined alveolar macrophages, immune cells that act as the lungs' cleanup crew. Exposure to the nanoplastics increased the production of reactive oxygen species (ROS), highly reactive molecules that can damage cells when produced in excess.
ROS production was closely associated with the inflammatory response, helping explain how nanoplastics can promote the recruitment of additional immune cells and contribute to lung tissue injury. Gene expression analysis also revealed changes in pathways involved in inflammation and immune regulation.
The findings show that nanoplastics can actively disrupt immune responses in the lungs under the experimental conditions tested. They also suggest that assessing airborne particles by mass alone may underestimate the inflammatory potential of nanoplastics.
The researchers emphasize the need for environmental and public health assessments that consider particle surface area and surface reactivity alongside mass. The study provides a scientific basis for refining future safety assessments of nanoplastics and other airborne particulate pollutants.
"This study demonstrates that nanoparticles of polyethylene and polypropylene, two plastics widely used in everyday life, can trigger lung inflammation through ROS production and surface reactivity following respiratory exposure," said Dr. Jinyoung Jeong, one of the study's corresponding authors. "We hope these findings will provide useful scientific evidence for moving beyond mass-based assessments of airborne hazards and developing more comprehensive environmental and public health criteria that account for the characteristics of nanoparticles."
The study was published online on September 30, 2026, in Journal of Hazardous Materials Advances (Impact Factor: 9.6), an international journal covering hazardous materials.
The article is titled "Comparative toxic potential of polypropylene and polyethylene nanoplastics using a mouse intratracheal instillation model"
The corresponding authors are Dr. Jinyoung Jeong of KRIBB and Professor Wan-Seob Cho of Dong-A University. The first author is Eunsol Bae of Dong-A University.
This research was supported by the Basic Science Research Program funded by the Ministry of Science and ICT and the Major Research Programs of the Korea Research Institute of Bioscience and Biotechnology (KRIBB).