Microplastic Toxicity: Unveiling the Physiological and Histopathological Impact on Cyprinus carpio
Keywords:
microplastic, Cyprinus carpio, toxicity, histopathology alterations, physiological parametersAbstract
Microplastic pollution has arisen as environmental concern related to their distribution and
adverse effect on aquatic organisms. The aim of this study was to evaluate the effects of
polyethylene microplastics (PE‑MPs) on Cyprinus carpio through physiological function
tests and histopathological assessment. Six groups (one control and five treatment groups)
were prepared with various microplastics concentrations (0.0, 5, 10, 15, 20, and 25 mg/kg)
for four weeks. Ten fish per tank with two replicates per group were used. Treated fish were
fed twice a day. Hematological tests showed significant changes (P < 0.05) in WBC, Hb, RBC,
and PCV levels in treated fish group compared with control group. WBC level increased
(26.00 cell x103 mm3) in group five, while it was recorded 7.96 cell x103 mm3 in control
group. Whereas, Hb, RBC, and PCV levels revealed a significant reduction, recording 5.47
g/dL, 0.96 cell×106 mm3, and 16.43%, respectively, for group five, in contrast to the control
group, which reached 11.1 g/dL, 2.00 cell×106 mm3 and 33.30%. Liver enzyme values
increased significantly, with AST reaching 156.88 IU/L and ALT 89.00 IU/L, in group five,
compared with 38.67 IU/L and 19.60 IU/L in the control group. Renal function analysis
demonstrated significant elevated levels of blood urea nitrogen (46.07 mg/dL) and
creatinine (1.70 mg/dL), compared with 14.43 mg/dL and 0.50 mg/dL in the control group.
Histopathological lesions observed in treated groups’ fish gills included blood congestion of
the central vein, dilatation, epithelial hyperplasia, increased mucous cells, and inflammatory
cell infiltration. The anterior intestine exhibited villi shortening and hyperplasia, with the
lamina propria showing moderate infiltration of mononuclear cells and goblet cell depletion.
Liver tissue exhibited cytoplasmic vacuolation, necrosis, aggregation of macrophages, blood
congestion, dilatation of sinusoid, and mononuclear cell infiltration. In conclusion, this study
found that PE-MPs impact on liver, renal function test, hematological profile and causing
histopathological changes. Chronic exposure led to fish health deterioration and mortality
risk related to increasing concentration directly.
Received: XX April 2026
Revised: XX August 2026
Accepted: 18 August 2026
Published: Online First
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