Microplastic presence in boar semen: potential risks for reproductive health

Microplastic particles (MPs), defined as plastic fragments measuring less than 5 millimeters, are increasingly detected in the environment due to the extensive production and degradation of plastic materials. Recent studies have demonstrated microplastic accumulation in various biological systems, including reproductive tissues, raising critical questions about their possible effects on human and animal reproductive health [1, 2]. The results of experimental studies have demonstrated that the introduction of MPs during artificial insemination procedures can impair fertility [3]. Therefore, the aim of the present study was to determine the presence of MPs in raw boar semen samples. Fresh, undiluted sperm samples (n = 12) were collected from healthy boars at breeding farms in Lithuania. To minimise secondary contamination, semen samples were collected directly into glass containers with metal lids. All experiments were performed using glassware that had been thoroughly cleaned with ultrapure water (Milli-Q). The detection of MPs was performed by modifying a standard protocol for digestion and filtration, followed by microscopic examination [4]. The presence of MPs was identified in all semen samples that were analysed. The MPs detected in this experiment ranged from less than 50 to 1000 µm in size. The most prevalent polymer types identified were polyethylene (detected in 91.6% of the samples), acrylates (in 75.0% of the samples), and polyester (in 75.0% of the samples), indicating the presence of multiple environmental plastic sources. These findings raise concerns regarding possible biological effects. Previous research indicates that MPs in male reproduction may induce oxidative stress, inflammation, and impaired spermatogenesis, potentially leading to reduced sperm motility, altered morphology, and compromised fertility outcomes [5]. This study provides the initial evidence of microplastic presence in boar semen and highlights the need for further investigations to clarify their impact on boar sperm quality and fertility, as this contamination has not been previously examined.