Size- and oxidative potential-dependent toxicity of environmentally relevant expanded polystyrene styrofoam microplastics to macrophages

• Published in: Journal of hazardous materials 2023-10, Vol.459, p.132295-132295, Article 132295
• Main Authors: Jeon, Soyeon, Jeon, Jun Hui, Jeong, Jiyoung, Kim, Gyuri, Lee, Sinuk, Kim, Songyeon, Maruthupandy, Muthuchamy, Lee, Kyuhong, Yang, Sung Ik, Cho, Wan-Seob
• Format: Article
• Language: English
• Subjects: cytokines; cytotoxicity; enterocytes; hepatocytes; humans; Inflammasome; inflammasomes; irradiation; macrophages; microplastics; oxidation; Oxidative potential; oxidative stress; particle size; pollutants; polystyrenes; Styrofoam; Toxicity; ultraviolet radiation; Weathering
• ISSN: 0304-3894; 1873-3336
• DOI: 10.1016/j.jhazmat.2023.132295

Expanded polystyrene (EPS), also known as Styrofoam, is a widespread global pollutant, and its lightweight floating property increases its chances of weathering by abrasion and ultraviolet (UV) irradiation, resulting in microplastics. Herein, we investigated the effects of particle size ((1 µm versus 10 µm), UV irradiation (pristine versus UV oxidation), and origin (secondary versus primary) on the toxicity of Styrofoam microplastics. The target cells used in this study were selected based on human exposure-relevant cell lines: differentiated THP-1 cells for macrophages, Caco-2 for enterocytes, HepG2 for hepatocytes, and A549 for alveolar epithelial cells. In the differentiated THP-1 cells, the levels of cytotoxicity and inflammatory cytokines showed size- (1 µm > 10 µm), UV oxidation- (UV > pristine), and origin- (secondary > primary) dependency. Furthermore, the intrinsic oxidative potential of the test particles was positively correlated with cellular oxidative levels and toxicity endpoints, suggesting that the toxicity of Styrofoam microplastics also follows the oxidative stress paradigm. Additionally, all microplastics induced the activation of the pyrin domain-containing protein 3 (NLRP3) inflammasome and the release of interleukin-1β (IL-1β). These results imply that weathering process can aggravate the toxicity of Styrofoam microplastics due to the increased oxidative potential and decreased particle size. [Display omitted] •Styrofoam polystyrene microplastics can be exposed to the environment and humans.•Smaller particles showed higher cytotoxic potential to macrophages.•Secondary microplastics were more cytotoxic than primary microplastics.•UV irradiation of microplastics aggravated intrinsic ROS and resultant toxicity.•Microplastics can activate the NLRP3 inflammasome in macrophages.