Effect of Microplastics Particles on the Rheological Properties of Human Saliva and Mucus

The level of air pollution by nano and microparticles raises rapidly. One of the methods of human exposure to nanoparticles is through inhalation. Indoor environments contain airborne plastic particles, primarily from synthetic textiles, leading to unintended inhalation or occupational exposure. In outdoor environments, exposure could happen through breathing in contaminated aerosols from ocean waves or airborne fertilizer particles from dried wastewater treatments. Airborne particles affect human health in various ways and they also act directly on the epithelium and its mucus layer after deposition in the mouth and respiratory system. Exposure via ingestion to microplastics present in the various environmental compartments may occur either directly or indirectly via the food chain or drinking water. The aim of the study was to determine the influence of plastic microparticles on the rheology of mucus and saliva, and thus on their functioning. The artificial mucus and saliva, as and plastic nanoparticles (namely PS – polystyrene and PE - polyethylene) were used in experiments. The rheological properties of saliva and mucus were determined with the use of an oscillatory rheometer, at various temperatures (namely 36.6 C and 40 C, what corresponds to the case of healthy and ill human) The results were compared with those obtained for pure saliva and mucus. The influence of the presence of the particles on the parameters of the constituitive viscosity equations was studied. The presence of plastic micro- and nanoparticles in the saliva and mucus may interfere with their physiological functions.