Dermal Cytotoxicity of the Methylammonium Lead Iodide Based Perovskites

Perovskite solar cells are attracting attention as next-generation photovoltaic technology, and their high efficiency and low cost have the potential to be a sustainable energy solution. However, lead contained in the standard perovskite material, methylammonium lead iodide (MAPbI<font size="1">3</font>) as an environmentally hazardous substance is a serious issue in practical use because of its known toxicity to humans. This study evaluates the effects of MAPbI₃ and related compounds on skin, particularly under light exposure, due to limited knowledge of their dermal toxicity.
Using a 3D cultured epidermal model (EPI-MODEL6D, Japan Tissue Engineering), we assessed the toxicity of MAPbI₃, methylammonium iodide (MAI), and lead iodide (PbI₂) on skin cells. The compounds were applied in powder form or culture medium for short (15 minutes) and long (up to 48 hours) exposure, simulating occupational conditions. Cell viability, inflammatory response via interleukin-8 (IL-8) release, and histological analysis were performed. Additionally, experiments using human melanoma cells (A375; CRL-1619, ATCC) were conducted to investigate the toxicity of MAPbI₃, MAI, and PbI₂, and to assess the possibility that these compounds contain nanoparticles. The samples were filtered through a 0.2 µm cellulose acetate membrane, and the presence of nanoparticles in the filtrate was confirmed using scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS). Furthermore, these cells were irradiated with white LED light or ultraviolet (UV) light for 15 minutes to investigate the effect of light irradiation on toxicity.
In the 3D cultured epidermal model, cell viability rapidly decreased after 15 minutes of contact with MAPbI₃, MAI, and PbI₂. These results suggest that these compounds exhibit cytotoxicity to the skin. In particular, the epidermal model in contact with MAPbI₃ showed significant morphological abnormalities. IL-8 levels did not rise significantly, suggesting inflammation is not the primary mechanism.
Using A375 melanoma cells showed that both MAPbI₃ and PbI₂ significantly reduced cell viability even after filtration, confirming that both the nanoparticles and spended compounds were toxic. SEM-EDS analysis detected lead-containing particles in the MAPbI₃ filtrate, with a size of several µm. Interestingly, MAI significantly increased cell viability, and this effect was enhanced by irradiation with white LED light. This suggests that MAImay promote tumor cell growth under light irradiation. When MAPbI₃-added cells were irradiated with light, the survival rate decreased even further, indicating that visible light can promote cell toxicity.
In this study, it was confirmed that methylammonium lead iodide perovskite and related compounds show strong cytotoxicity against human skin models and melanoma cells, and it was suggested that lead is the main cause. It was also found that these compounds penetrate the skin tissue as nanoparticles and that their toxicity is enhanced by light irradiation. These results emphasize the need for protective measures to prevent skin exposure during the manufacture and handling of perovskite solar cells. Furthermore, occupational safety measures need to be established to consider the risk of increased cell toxicity and promotion of tumor cell growth due to light irradiation. In the future, further research is needed to develop lead-free perovskite materials and to assess the effects of long-term exposure.