Toxicity of polyethylene terephthalate microplastics and dimethyl phthalate in male Sprague-Dawley rats: Insights into oxidative stress, DNA damage, and histopathological impacts

The combined toxicity of polyethylene terephthalate (PET) microplastics and dimethyl phthalate (DMP) remains poorly understood, particularly concerning oxidative stress and organ-specific impacts. Given the increasing environmental contamination of microplastics and plastic additives, this study aimed to investigate their synergistic effects on oxidative stress, DNA damage, and histopathological alterations in male Sprague-Dawley rats. Over a 28-day exposure period, plasma 8-hydroxy-2'-deoxyguanosine (8-OHdG) levels significantly increased in the high-dose co-exposure group (PET 5 mg + DMP 25 mg/kg/day; 27.99 ± 3.02 ng/mL) compared to the control group (10.65 ± 1.12 ng/mL, p < 0.05), indicating oxidative DNA damage. However, OGG1 gene expression remained unchanged (p = 0.5736), suggesting a limited DNA repair response. Histopathological analysis revealed severe hepatic steatosis and cellular degeneration in the co-exposure groups, accompanied by significant liver hypertrophy (13.88 ± 0.95 g vs. 9.38 ± 0.62 g in controls; p < 0.01). Although renal tissues exhibited hypertrophy, no structural damage was observed. These findings underscore the potential health risks posed by chronic exposure to microplastics and plasticizers, particularly their cumulative effects on liver pathology. Future studies should explore molecular interactions between PET and DMP to elucidate their long-term toxicological implications in environmental and human health contexts.