Cadmium Concentrations in Blood and Seminal Plasma: Correlations with Sperm Number and Motility in Three Male Populations (infertile Couples, Artificial Insemination Donors and Unselected Volunteers)

To investigate a possible common environmental exposure that may partially explain the observed decrease in human semen quality, we correlated seminal plasma and blood cadmium levels with sperm concentration and sperm motility. We studied three separate human populations: [Group 1] infertility patients (Long Island, NY), [Group 2] artificial insemination (AI) donors (Rochester, NY), and [Group 3] general population volunteers (Rochester, NY). Information about confounding factors was collected by questionnaire. Seminal plasma cadmium did not correlate with blood cadmium (Spearman correlation, n = 91, r = -0.092, P = 0.386, N.S.). Both blood and seminal plasma cadmium were significantly higher among infertility patients than the other subjects studied (e.g., median seminal plasma cadmium: 0.282 μg/L [infertility patients] vs. 0.091 μg/l [AI donors] and 0.092 μg/ [general population volunteers]; Kruskal-Wallis test, P<0.001). percent motile sperm and sperm concentration correlated inversely with seminal plasma cadmium among the infertility patients (respectively, r = -0.201, P<0.036 and r = -0.189, P<0.05), but not in the other two groups. Age (among infertility patients) was the only positive confounder correlating with seminal plasma cadmium. To validate our human findings in an animal model, we chronically exposed adolescent male Wistar rats to low-moderate cadmium in drinking water. Though otherwise healthy, epididymal sperm count and sperm motility decreased with cadmium dose and time of exposure. Our human and rat studies are consistent with the hypothesis that environmental cadmium exposures may contribute significantly to reduced human male sperm concentration and sperm motility.