Male Reproductive Effects of Lead, Including Species Extrapolation for the Rabbit Model

• Published in: Reproductive toxicology (Elmsford, N.Y.) N.Y.), 1998-05, Vol.12 (3), p.333-346
• Main Authors: Moorman, William J., Skaggs, Stephen R., Clark, John C., Turner, Terry W., Sharpnack, Douglas D., Murrell, James A., Simon, Stephen D., Chapin, Robert E., Schrader, Steven M.
• Format: Article
• Language: English
• Subjects: Animals; Biological and medical sciences; blood lead; Chemical and industrial products toxicology. Toxic occupational diseases; Humans; lead; Lead Poisoning - blood; Linear Models; Male; Medical sciences; Metals and various inorganic compounds; Models, Biological; Nonlinear Dynamics; rabbit model; Rabbits; Reproduction - drug effects; Semen - drug effects; semen quality; Species Specificity; Sperm Count - drug effects; Sperm Motility - drug effects; Spermatozoa - drug effects; Spermatozoa - ultrastructure; Toxicology
• ISSN: 0890-6238; 1873-1708
• DOI: 10.1016/S0890-6238(98)00010-0

The effects of elevated blood lead on semen quality were evaluated in the rabbit model and compared to published effects in humans. Mature, male rabbits were given lead acetate by subcutaneous injection in the dose range of 0 to 3.85 mg/kg on a Monday-Wednesday-Friday basis. In each of eight treatment groups, a dosing regimen was developed to produce blood lead levels of 0, 20, 40, 50, 70, 80, 90, and 110 μg/dL. A 5-week pre-exposure period was followed by a 15-week exposure testing period allowing for response through six cycles of the seminiferous epithelium. Semen analyses revealed that increased blood lead levels were associated with adverse changes in the sperm count, ejaculate volume, percent motile sperm, swimming velocities, and morphology. Hormonal responses were minimal. Testicular pathology revealed a dose-dependent inhibition of spermiation. For six measures of semen quality, threshold estimates ranged from 16 to 24 μg/dL. Using the species extrapolation factor derived in this study, a rabbit dose would have to be divided by 1.56 to obtain the equivalent human dose for an equal percentage decrease in sperm concentration; however, rabbits are 3.75 more sensitive in terms of absolute decrease in sperm count for a given blood lead level.