Nanoplastics cause acute lung inflammation in mice

Researchers in South Korea have found that polyethylene and polypropylene nanoparticles can cause acute lung inflammation in mice when particles are experimentally introduced into the trachea. The work was carried out by a team of scientists from the Korea Research Institute of Bioscience and Biotechnology together with Dong-A University, News-Medical reports.

The scientists prepared polyethylene (PE) and polypropylene (PP) nanoparticles, two common types of plastic used in everyday products. Their effects on the lungs were compared with those of diesel exhaust particles. In the experiment, the particles were administered directly into the mice's tracheas, after which the inflammatory response and the biological mechanisms accompanying it were assessed.

Both types of nanoplastics caused acute inflammation. Their relative inflammatory activity depended on the method used to measure the dose. When particle mass was compared, polyethylene nanoplastics caused a response at least as strong as that caused by diesel particles. When the dose was compared by particle surface area, both polyethylene and polypropylene nanoplastics had greater inflammatory potential than diesel particles.

The researchers also studied alveolar macrophages, immune cells that clear foreign particles from the lungs. After contact with nanoplastics, their production of reactive oxygen species increased. An excess of these species can damage cells; in the study, this process was closely linked to inflammation, the recruitment of additional immune cells and damage to lung tissue.

Gene expression analysis also revealed changes in mechanisms associated with inflammation and the regulation of the immune response. The authors note that assessing air pollutants by mass alone may underestimate the inflammatory potential of nanoplastics. They propose that future safety assessments also take into account particle surface area and surface reactivity.