Oral Polystyrene Microplastics Caused Dose-Related Hepatorenal Injury in Mice
Oral exposure to polystyrene microplastics produced a clear dose-response pattern of liver and kidney injury in BALB/c mice over 28 days. Across serum chemistry and histology, the highest particle burden tracked with the worst organ damage, turning a pollution question into a toxicology signal with direct biological consequences.
The experiment used forty healthy adult male mice divided into four groups of ten. One group received distilled water, while the others were gavaged daily with 10, 20, or 30 mg/kg/day of PS-MPs for 28 consecutive days. The particles were spherical polystyrene microspheres with a nominal diameter of 5.0 μm, a size range that favors ingestion-related exposure and systemic interaction after gastrointestinal transit. After the exposure period, investigators assessed serum biomarkers of liver and kidney function and examined tissue sections for structural injury.
Serum Biomarkers Rose as Dose Increased
Biochemistry moved in the same direction as the particle dose. ALT, AST, ALP, bilirubin, creatinine, and urea all increased with PS-MP exposure, with statistically significant trends across the dosing groups. The reported P values were 0.0247 for ALT, 0.0192 for AST, 0.0044 for ALP, 0.0045 for bilirubin, 0.0029 for creatinine, and 0.0006 for urea.
Those changes matter because they map onto two distinct organ systems at once. Rising aminotransferases reflect hepatocellular stress and membrane injury, while ALP and bilirubin point toward hepatobiliary dysfunction. Creatinine and urea move in parallel when filtration and tubular handling begin to fail. The combined pattern suggests that the particles did not simply irritate one tissue compartment; they produced a broader toxic burden involving both hepatic metabolism and renal excretion.
The most direct biochemical clue came from correlation analysis. Creatinine correlated strongly with urea, with an r value of 0.7628 and P < 0.0001, reinforcing the linkage between the two renal markers. ALP also correlated positively with bilirubin, with r = 0.5229 and P = 0.0087, supporting a coherent hepatobiliary injury pattern rather than a random scatter of abnormal laboratory results.
Tissue Injury Deepened With Higher Exposure
Histopathology gave the biochemical signal visible form. The liver showed increasing inflammatory infiltration, hepatocellular degeneration, necrosis, and sinusoidal dilatation as the dose rose. The kidney showed tubular epithelial degeneration and necrosis, again worsening with greater PS-MP exposure. Semi-quantitative lesion scores differed significantly across groups, with Kruskal–Wallis P < 0.0001 and the greatest injury in the high-dose arm.
A single sentence captures the tissue-level meaning: the highest particle dose produced the most severe structural damage in both organs.
This pattern is biologically plausible. The liver is the first major metabolic checkpoint after oral exposure, and the kidney becomes vulnerable when circulating toxicants, inflammatory mediators, or particle-associated stress signals reach the renal microvasculature and tubular system. Microplastics may contribute injury through oxidative stress, cellular membrane disruption, mitochondrial dysfunction, and local inflammatory responses. Even without direct mechanistic assays in this experiment, the injury phenotype fits that framework closely enough to make the toxicology signal difficult to dismiss.
Why the Liver and Kidney Were the Right Organs to Watch
The liver and kidneys sit at the center of xenobiotic handling. The liver processes absorbed compounds and bears the brunt of metabolic overload, while the kidneys filter circulating waste and concentrate toxic stress within vulnerable tubules. When a contaminant can affect both organs simultaneously, the concern extends beyond isolated biomarker drift and toward a systemic exposure problem.
Microplastics are especially relevant because they are now encountered through food, drinking water, soil, and air. Polystyrene is one of the most common polymers in disposable products and packaging, which increases the likelihood of chronic low-level exposure. The small size and chemical stability of these particles make them plausible candidates for persistence in biological tissues after ingestion. In that context, the finding of dose-related injury in mice is not an abstract laboratory artifact; it is an experimental warning about what repeated oral exposure can do to organs built to metabolize and eliminate foreign material.
What the Mouse Data Do and Do Not Prove
This study provides experimental evidence of hepatorenal toxicity after repeated oral PS-MP exposure, but the scope remains specific. The work was done in male BALB/c mice, not humans, and it covered a 28-day exposure window rather than the longer time horizon most people associate with environmental contamination. The dose levels were also controlled and deliberately graded, which is useful for toxicology but not a direct model of everyday human exposure.
Even with those limits, the study is valuable because it paired serum chemistry with histopathology instead of relying on a single readout. That combination strengthens the conclusion that the biochemical abnormalities reflected true organ injury rather than isolated laboratory noise. The absence of animal deaths, early euthanasia, or humane endpoint violations also suggests the observed organ toxicity developed without overt systemic collapse, which may be clinically relevant in thinking about subacute toxic exposure.
A Toxicity Signal That Warrants Mechanistic Follow-Up
The next question is not whether PS-MPs can injure mouse liver and kidney tissue; this experiment shows that they can under repeated oral exposure. The more important issue is which pathways drive that damage and whether similar effects occur at lower, more environmentally realistic exposure levels over longer periods. Oxidative stress, inflammation, and mitochondrial injury remain the most plausible candidates, but they were not directly measured here.
Future work should connect dose, tissue accumulation, and mechanistic biomarkers in a way that clarifies threshold effects and organ susceptibility. For now, the practical message is narrower: repeated oral exposure to polystyrene microplastics produced dose-dependent biochemical abnormalities and worsening structural injury in the liver and kidneys of mice, with the heaviest burden landing in the highest-dose group.