Investigating the carcinogenic and synergistic effects of microplastics isolated from daily used cosmetics on NHDFs and A431 by using anti-cancer drug (5-FU) treatment

Cosmetics with microplastic beads contribute significantly to microplastic (MPs) contamination. In this investigation Polyethylene microplastic (PE-MP) beads were isolated from commercial face wash (FW-MPs) and face scrubs (FS-MPs) and were exposed to human epidermoid carcinoma (A431) and normal human dermal fibroblasts (NHDFs) cells for various time points (6, 24, 48, 72, and 96 h). Cell viability assays revealed that PE-MPs significantly (p < 0.001) enhanced the proliferation of A431 cell growth overtime (27 % to 97 % and 24 % to 99 % for FW-MPs and FS-MPs, respectively). NHDF cell growth was observed to be significantly decreased overtime when treated with PE-MPs (82 % to 12 % and 85 % to 16 % for FW-MPs and FS-MPs, respectively) indicating its harmful effects on human skin cells. 5-fuorouracil (5-FU) is a known drug for treating cancer by promoting apoptosis or cell death. This study also showed increased cell death (17 % to 11 %) of A431 cells overtime (6 to 96 h) when treated with 5-FU. However, the rate of cell death was observed to decreased overtime when cells were treated with 5-FU + PE-MPs (21 % to 45 % and 20 % to 46 % for 5FU + FW-MPs and 5FU + FS-MPs, respectively) compared to pristine 5-FU. Changes in oxidative stress and antioxidant enzymes activities were also observed both the treated cells. Additionally, morphological changes were observed for PE-MPs treated A431 cells. Overall, in vitro evidence suggests that cosmetic MPs are hazardous for human normal skin and reduce the efficacy of 5-FU. This adds to our understanding of the health risks of everyday skin care products.