Individual and combined effects of microplastics and diphenyl phthalate as plastic additives on male goldfish: A biochemical and physiological investigation

The development of the plastics industry worldwide has led to an increase in the rate of plastic waste and chemical additives such as microplastics (MPs) and diphenyl phthalate (DPP) in the environment. The penetration of these pollutants into aquatic ecosystems has also raised concerns about their toxic effects, individually and in combination. The present study investigated the individual and combined toxicity of MPs and DPP on the health of male goldfish. A 28-day exposure experiment was conducted using different concentrations of DPP (2.5, 5.0, 7.5 μL L^-1) and MPs (20, 40 mg L^-1), both individually and in combination. Biochemical markers, enzyme activities, and hormone levels were evaluated to ascertain the effects on metabolic, renal, and reproductive health. The findings revealed that concurrent exposure to DPP and MPs markedly elevated plasma glucose, creatinine, triglycerides, and cholesterol levels, accompanied by notable reductions in high-density lipoprotein and low-density lipoprotein. Moreover, combined exposures resulted in liver damage, as evidenced by elevated serum glutamic-oxaloacetic transaminase, serum glutamic-pyruvic transaminase, alkaline phosphatase, lactate dehydrogenase, and gamma-glutamyl transferase activities and disruptions in protein synthesis and immune response, with notable decreases in total protein, albumin, and globulin. Testosterone levels decreased, while estradiol levels increased, indicating endocrine disruption and potential reproductive impairment. These findings indicated the adverse synergistic effects of MPs and DPP on the physiology of goldfish. Therefore, further research must be conducted to increase our knowledge of their ecotoxicological risks.