Despite stopping respiratory viruses such as Covid-19,  disposable face masks can cause lung damage due to their main ingredient, a study found. 

Polypropylene (PP) is the main raw material of disposable masks and is a microplastic commonly encountered as disposable items in everyday life.

Recent reports have suggested that weathered PP microparticles can be inhaled. However, the inhalation toxicology of PP microparticles is poorly understood.

According to the study by the Korea Institute of Toxicology, microplastics are plastics that have been changed into fine particles by physical force.

It is known that microplastic particles of 5 μm or less infiltrate lung tissue through inhalation, and nanoplastics of 1 μm or less reach the alveoli and cause various respiratory diseases such as asthma and pulmonary fibrosis.

To confirm that PP causes damage to the respiratory system, the research team dropped PP nanoplastic into the respiratory tract of the animals and observed lung damage.

As a result, the team observed inflammatory damage, particularly a neutrophilic inflammatory response, in the lungs of the experimental animals.

Neutrophils are cells that play a major role in innate immunity, but when abnormally increased and activated, neutrophils can cause an inflammatory response in the lungs.

The team also exposed the human lung cancer epithelial cell line (A549) to PP nanoplastic to confirm the mechanism of lung damage and found mitochondrial damage in human lung cancer epithelial cell lines.

“The study has established a clear basis for inhalation toxicology by confirming the harm to the human body following inhalation exposure to PP nanoplastic,” the research team said. “In the future, we plan to conduct various studies between microplastics and inhalation toxicity studies.”

The study result was published in the latest issue of Particle and Fibre Toxicology.