G-1972

Impact of Microplastics on Semen Quality and Testicular Function: A Systematic Review of human and animal studies

 Mohammad Reza Rahmani ¹ ℗, Ali Jafarian Yazdi ² ©, Yeganeh Rajabi ³, Saeed Heidarzade ³, Fatemeh Mirnezhad ¹   

 
Abstract

Introduction: Semen quality in men is declining and affects male infertility. Microplastics are small plastic particles less than 5 mm in size that are found in freshwater sources, oceans, food, and even in the air. This systematic review aimed to evaluate the impact of microplastics on semen quality. Search Strategy: This study followed the PRISMA guidelines for systematic reviews. An advanced search was conducted in PubMed / MEDLINE, Scopus, Web of Science, and Google Scholar using relevant MeSH terms, including "Microplastics," "Semen quality," and "Male infertility," covering published literature up to March 10, 2025. Inclusion criteria were as follows: 1) Original clinical, experimental, or observational studies 2) Human or animal studies examining the effects of microplastics on semen quality 3) Articles published in English 4)Full-text availabity. Exclusion criteria included: 1)Reviews, editorials, letters to the editor, commentaries, and conference abstracts 2)Studies not directly assessing semen quality or reproductive endpoints 3)Articles not aligned with the PICO framework 4)Studies rated as low quality based on risk of bias assessment. In assessing the quality of animal studies using the SYRCLE tool, they were of medium to high quality. Human studies were also assessed using the NOS tool and received scores of 6 to 8. Results: In our systematic review, based on the defined objectives and comprehensive searches conducted in major scientific databases, a total of 35 articles were initially identified. After removing 3 duplicate records, 32 titles were screened. Subsequently, 5 articles were excluded due to irrelevance. The abstracts of the remaining 27 articles were evaluated, resulting in the exclusion of 2 additional studies. The full texts of the remaining articles were then thoroughly assessed. Based on access limitations, relevance to the study topic, and predefined inclusion and exclusion criteria, 12 articles were excluded. Ultimately, 13 studies met all criteria and were included in the final analysis. Microplastics reduce male fertility and even cause infertility. They enter the testes, induce oxidative stress, and affect the expression of genes associated with apoptosis and inflammation. As a result, they not only damage the structure and function of the testes, but also reduce sperm count and quality, ultimately reducing male fertility. In addition to causing severe testicular toxicity, PS NPs inhibit sperm capacitation by disrupting RAC1 and CDC42-dependent proteins. Conclusion and Discussion: The findings of this study suggest that exposure to microplastics can affect male reproduction and lead to reduced sperm quality. However, further high-quality research is needed to better clarify the mechanisms and consequences of microplastic exposure on semen quality.

Keywords: Microplastics, Semen quality, Male infertility