Evaluation of the Nephrotoxic and Oxidative Stress Effects of Polyethylene Terephthalate 1 Microplastics and Cornstarch-Based Bioplastics in Albino Rats
Keziah Levi *
Department of Clinical Chemistry, Faculty of Medical Laboratory Science, Rivers State University, Port Harcourt, Nigeria.
Ibitoroko George-Opuda
Department of Clinical Chemistry, Faculty of Medical Laboratory Science, Rivers State University, Port Harcourt, Nigeria.
Ibioku Elekima
Department of Clinical Chemistry, Faculty of Medical Laboratory Science, Rivers State University, Port Harcourt, Nigeria.
*Author to whom correspondence should be addressed.
Abstract
Background: The increasing environmental presence of microplastics and the growing use of bioplastics have raised concerns regarding their potential effects on renal function, oxidative balance, and cellular integrity.
Aim: This study assessed the effects of polyethylene terephthalate 1 (PET-1) microplastics and bioplastics on selected renal, oxidative stress, and DNA damage markers in albino rats.
Methods: A total of 105 male and female albino rats were randomly assigned to three groups. The experiment was conducted over three exposure periods of 30, 60, and 90 days. The treatment groups comprised two main categories: bioplastic and PET-1 microplastic. Each category was further divided into three dose groups: BP1, BP2, and BP3 for the bioplastic treatments, and MP1, MP2, and MP3 for the PET microplastic treatments, corresponding to the low, intermediate, and high doses, respectively. The treated feed was prepared daily by thoroughly mixing the appropriate quantity of the test material with 50 g of feed and placing it in the respective cages for consumption. At the end of each exposure period, blood samples were collected and analysed for kidney injury molecule-1 (KIM-1), urea, creatinine, glutathione peroxidase (GPx), malondialdehyde (MDA), and DNA damage molecules (DNA DMs). Kidney tissues were also collected to determine the histological changes after exposure. Data were expressed as mean ± standard deviation and analysed using one-way analysis of variance followed by Tukey’s post hoc test, with statistical significance set at p<0.05.
Results: The results showed that after 90 days of high-dose exposure, PET-1 exposure was associated with significant elevations in KIM-1 (from 15.92±3.92 to 66.75±2.97 pg/ml), MDA (from 1.19±0.35 to 4.29±0.38 mmol/ml), 8-OHdG (from 71.23±3.83 to 116.7±1.44 pg/ml), creatinine (from 0.45±0.20 to 1.29±0.09 mg/dl), and urea (from 25.20±4.76 to 57.0±5.48 mg/dl), while depleting GPx from 127.0±7.88 to 33.50±5.88 pg/ml. Histopathology revealed severe glomerular lesions, tubular swelling, and cellular hyperplasia in PET-treated rats. In contrast, bioplastics caused only mild alterations, with creatinine and urea remaining non-significant (p>0.05) and histopathology showing only slight glomerular distortion.
Conclusion: The findings suggest that these materials may have nephrotoxic and oxidative effects, with the magnitude of response influenced by the dose and duration of exposure.
Keywords: Microplastics, Polyethylene terephthalate (PET), bioplastics, nephrotoxicity, kidney injury Molecule-1 (KIM-1), oxidative stress, Malondialdehyde (MDA), 8-Hydroxy-2′-deoxyguanosine (8-OHdG)