The synergetic effects of 4-nonylphenol and polyethylene microplastics in Cyprinus carpio juveniles using blood biomarkers

Abstract

Microplastics are widely distributed in aquatic ecosystems along with other chemical pollutants. Therefore, it is vital to study the health-hazardous effects of MPs in combination with 4-nonylphenol (4-NP), which is a highly abundant industrial waste and a critical alkylphenol endocrine disruptor. We investigated the effects of the exposure to polyethylene microplastics (PE-MPs), 4-NP, and their combination on blood biomarkers in Cyprinus carpio juveniles. Four study groups were treated for 15 consecutive days: (1) control group, (2) 10 mg/L PE-MP group, (3) 10 mg/L PE-MPs + 200 µg/L 4-NP group, and (4) 200 µg/L 4-NP group, followed by 15 days of recovery. Biochemical analyses showed that creatine kinase, lactate dehydrogenase, glucose, liver enzymes, total protein, and A/G ratios were significantly increased after exposure to PE-MPs, 4-NP, and the combination. Hematological parameters (RBC's, Hb, Ht, neutrophil percentage, and WBC's) were significantly decreased in the three exposure groups, whereas mean corpuscular volume and lymphocyte percentages were significantly increased. The 15-day recovery period improved most hematobiochemical parameters and PE-MP accumulation indices. Taken together, we demonstrated the hazardous effects of PE-MP and 4-NP combinations on C. carpio blood parameters and highlighted their potential risk to human health.

Figure 1

(a) Transmission electron microscope and (b) light microscope images of PE-MPs.

Figure 2

Light microscope images showing PE-MPs in fish, (a, b) Control, (c, d) 10 mg/L PE-MPs, and (e, f) 10 mg/L PE-MPs + 200 µg/L 4-NP.

Figure 3

RBC's percentage alterations in juveniles Cyprinus carpio after exposure to 10 mg/L PE-MPs, 10 mg/L PE-MPs + 200 µg/L 4-NP, and 200 µg/L 4-NP for 15 days each and after 15 days of recovery. Different letters indicate significant differences (P < 0.05).

Figure 4

RBC's nuclear abnormality percentages in juveniles Cyprinus carpio after exposure to 10 mg/L PE-MPs, 10 mg/L PE-MPs + 200 µg/L 4-NP, and 200 µg/L 4-NP for 15 days each and after 15 days of recovery. Different letters indicate significant differences (P < 0.05).

Figure 5

Blood smears from juveniles Cyprinus carpio after a 15-day exposure showing normal erythrocytes in the control group (a) and deformed erythrocytes in the 10 mg/L PE-MPs (b), 10 mg/L PE-MPs + 200 µg/L 4-NP (c), and 200 µg/L 4-NP groups (d). Eliboat shapes (Eli), teardrops (Tr), schistocytics (Sch), swollen cells (Sc), eccentric nucleus (Ecn), kidney shapes (Kn), crenated cells (Cr), sickle cells (Sk), acanthocytes (Ac), vacuolated cells (Vc), elliptocytes (Elip), spinocytes (Spc), and hemolyzed cells (Hc) (hematoxylin & eosin staining).

Figure 6

Blood smears from juveniles Cyprinus carpio after a recovery period of 15 days showing normal erythrocytes in the control group (a) and deformed erythrocytes in the 10 mg/L PE-MPs (b), 10 mg/L PE-MPs + 200 µg/L 4-NP (c), and 200 µg/L 4-NP groups (d). Schistocytic (Sch), swollen cells (Sc), eccentric nucleus (Ecn), crenated cells (Cr), acanthocytes (Ac), vacuolated cells (Vc), ameboied cells (Amc), spinocytes (Spc), and hemolyzed cells (Hc) (hematoxylin & eosin staining).