Exploring the association between metal(loid)s and human semen quality: a preliminary case study in a petrochemical complex

Occupational exposure to metal(loid)s in petrochemical industries has raised concerns about possible effects on male reproductive health. This study examines the link between metal(loid) exposure and semen quality parameters among petrochemical workers (PWs) compared to a non-petrochemical control group, using the WHO 2021 reference values as a standard. A cross-sectional analysis was performed on 176 healthy individuals, consisting of 22 PWs and 154 controls. Blood levels of arsenic (As), chromium (Cr), lead (Pb), tin (Sn), and thallium (Tl) were analyzed, and semen quality parameters, such as sperm concentration, total sperm count, motility, morphology, vitality, and volume, were evaluated and considered the main outcomes of the study. Overall, concentrations and detection frequencies were relatively low, indicating a scenario of low-level exposure. Petrochemical workers showed lower blood concentrations of Cr, Sn, and Pb compared to controls. Detection frequencies were higher in the petrochemical group than in controls (p > 0.05). Semen quality analysis revealed that PW had non-significant (p > 0.05) higher total sperm count, normal morphology, and vitality and statistically significant (p < 0.05) higher sperm concentration than controls. On the contrary, total motility and volume were non-significantly lower in PWs than in controls. Correlation analysis confirmed significant associations among semen parameters and identified positive associations between Pb and total motility (ρ = 0.24, p < 0.01) and Cr and Sn (ρ = 0.38, p < 0.001). In turn, Pb showed a positive association with total motility (ρ = 0.24, p = 0.001), abstinence (ρ = 0.17, p < 0.05), sperm concentration (ρ = 0.16, p < 0.05), and sperm count (ρ = 0.17, p < 0.05). Additionally, linear and logistic regression models demonstrated a significant positive association between blood Pb and total motility (β 3.58%, CI 1.01-6.15; OR 0.73%, CI 0.13-1.59). The results of the present study highlight the complexity of metal(loid) exposures and suggest that lifestyle and other environmental factors may influence semen quality. Longitudinal studies are warranted to better understand these associations.