Exposure to multiple metals/metalloids and human semen quality: A cross-sectional study.

BACKGROUND: Exposure to metals/metalloids, including essential and nonessential elements, has been associated to male reproductive health in animals. However, findings from human studies are inconsistent. OBJECTIVES: To investigate the impact of exposure to multiple metals/metalloids at environmental levels on the conventional human semen-quality parameters. MATERIALS AND METHODS: Men living in rural or industrial areas were recruited by personalized letters. No exclusion criteria were applied. Each man provided one semen sample and one blood sample. We analyzed the semen sample both to determine conventional sperm parameters (concentration, progressive motility and normal forms) and to quantify lead (Pb), cadmium (Cd), mercury (Hg), arsenic (As), nickel (Ni), vanadium (V) and selenium (Se) levels. The levels of these metals/metalloids were also quantified in venous blood and spermatozoa samples. Associations between the blood/seminal plasma metal/metalloid levels and semen quality parameters were assessed using confounder adjusted logistic regression models. Correlation and interactions between blood/seminal plasma and semen metal/metalloid levels were investigated using the Spearman's correlation. RESULTS: We found a positive association of seminal plasma cadmium level with lower Total count (OR = 4.48, 95%CI 0.25-80); whereas lead (OR = 4.51, 95%CI 0.86-23) and cadmium (OR = 3.45, 95%CI 0.77-16) seminal plasma levels had a positive association with progressive sperm motility. Overall, these associations remained suggestive after adjustment, though statistically unstable risks. Finally, we found weak interactions between beneficial effects of Se and detrimental ones only for Cd and Pb blood level on sperm concentration, total sperm count and progressive sperm motility. CONCLUSIONS: Our findings suggest that environmental exposure to Pb and Cd contributes to a decline in human semen quality, whereas Se can have beneficial effects. Measurements of metals/metalloids in the seminal fluid may be more predictable of semen quality than conventional blood measurements.

Sperm of patients with severe asthenozoospermia show biochemical, molecular and genomic alterations.

The multifactorial pathological condition, that is, severe low sperm motility is a frequent cause of infertility. However, mechanisms underlying the development of this condition are not completely understood. Single abnormalities have been reported in sperm of patients with asthenozoospermia. In this study, we characterized, in 22 normozoospermic men and in 37 patients with asthenozoospermia, biochemical, molecular and genomic abnormalities that frequently occur in sperm of patients with asthenozoospermia. We evaluated a panel of sperm biomarkers that may affect the motility and fertilizing ability of sperm of patients with severe asthenozoospermia. Since reactive oxygen species (ROS) production is involved in the pathogenesis of such sperm abnormalities, we determined the association between ROS production and sperm abnormalities. High percentage of patients with severe asthenozoospermia showed increased basal and stimulated ROS production. Moreover, these patients showed increased mitochondrial DNA (mtDNA) copy number but decreased mtDNA integrity and they were associated with elevated ROS levels. Furthermore, mitochondrial membrane potential was also significantly decreased and again associated with high ROS production in these patients. However, the rate of nuclear DNA fragmentation was increased only in less than one-fifth of these patients. An important cohort of these patients showed multiple identical biochemical, molecular and genomic abnormalities, which are typical manifestations of oxidative stress. The most frequent association was found in patients with high ROS levels, increased mtDNA copy number and decreased integrity, and low MMP. A smaller cohort of the aforementioned patients also showed nDNA fragmentation. Therefore, patients with asthezoospermia likely present reduced fertilizing potential because of such composed abnormalities.