Impact of common heavy metals and trace elements on semen quality: a meta-analysis and bibliometrics

Emerging evidence highlights a link between heavy metal exposure and semen quality, but discrepancies persist regarding the effects of metals like lead and cadmium across different biological matrices. This systematic review and meta-analysis aimed to explore the association between heavy metal exposure in blood, urine, and seminal plasma and male semen quality. A comprehensive search was conducted across four databases (PubMed, Embase, Scopus, and Cochrane Library), and a bibliometric analysis was performed using the Web of Science Core Collection. Based on this analysis, a systematic literature review and meta-analyses were conducted. Database searches were updated until November 2024. A total of 10 qualitative and 14 quantitative studies were included. Exposure to lead and cadmium in seminal plasma was significantly correlated with progressive sperm motility, with odds ratio (OR) of 2.27 (95% confidence interval [CI]: 1.18 to 4.34) for lead and of 2.55 (95% CI: 1.29 to 5.03) for cadmium. Arsenic exposure was significantly linked to total sperm motility (OR = 2.88, 95% CI: 1.35 to 6.17), while zinc deficiency in seminal plasma was associated with reduced total sperm motility (OR = 1.77, 95% CI: 1.17 to 2.66). Given the widespread exposure to heavy metals, assessing their impact on male reproductive health should be prioritized as a public health concern. This study highlights the reprotoxicity of heavy metals in seminal plasma, blood, and urine, with seminal plasma emerging as the most sensitive biomarker for reproductive risk.