Evaluating the Effects of Nano and Microplastics on Epidermal Barrier Function

The skin acts as a vital barrier against external factors, including nanoplastics (NPs)—ubiquitous environmental materials with unknown effects on the skin. NPs originate from the breakdown of plastic bottles, tires, paints, and cosmetics and spread through ingestion, inhalation, and contact. However, their effects on the skin barrier remain unknown. We investigated the impacts of polystyrene (PS) NPs on barrier function using biomimetic skin cultures. Daily PS-NP (100 nm) exposure (4h) for seven days reduced barrier function by 40% at all tested doses (1, 10, 100 ppm) via transepithelial electrical resistance. This was not due to cytotoxicity, as exposure up to 120 h did not alter keratinocyte growth or morphology (N=3) in a 2D DNA assay. Further analysis showed decreased expression of filaggrin, loricrin, and claudin 4 in 3D epidermis organoids at 1 ppm PS-NPs. Our data indicate NPs compromise the skin barrier, likely by reducing proteins critical to its function. As NPs in the environment will only continue to increase, understanding the consequences of skin exposure is imperative to comprehend how these environmental exposure agents affect humans.