P-43: Reproductive Toxicity of Low Metal Exposureon Male

Background: Recent evidence has indicated a deterioration in reproductive health of men in many countries over the past few decades, particularly a decrease in semen quality and an increase in prevalence of prostate cancer. The human male has a relatively low fertility potential as compared to other mammals. Thus, the human male may be at greater risk from reproductive toxicants. For example, the number of sperm per human ejaculate is typically only 2- to 4-fold higher than the number at which fertility is significantly reduced, whereas the number of sperm in rat, rabbit, or bull ejaculate is many times (up to 1400-fold) the number that will produce maximum fertility. The human male may be more susceptible than the rat to metal toxicity, possibly because of the poorer efficacy of the antioxidant defense system [lower systemic levels of glutathione, vitamin C, and glutathione peroxidase, compared to those in the rat . Furthermore, because of differences among species in reproductive end-points and in the route, level, and duration of metal exposure, experimental animal data cannot be extrapolated to the human situation and may not be useful for estimates of allowable human exposure. The aim of this review study is to explore associations between exposure to metals and male reproductive hormone levels. Materials and Methods: This review article prepared by studdying articles obtained from Google , pub med sites with key words such as: Human semen quality; Sex hormones;; lead exposure; Toxic and essential metals interaction.Results: An increase in blood lead is associated with increasing in immature sperm concentration, in percentages of pathologic sperm, wide sperm, round sperm, and short sperm, in serum levels of testosterone and estradiol, and a decrease in seminal plasma zinc and in serum prolactin. These reproductive effects wereobserved at low-level lead exposure (BPb median 49 mg/L, range 11–149 mg/L) common for general populations worldwide. An increase in blood cadmium was associated with increasing percentage of amorph sperm and serum testosterone . In addition to direct toxicity, Pb and Cd can interfere with the metabolism of certain essential elements including copper (Cu), zinc (Zn) and selenium (Se) by affecting their absorption, distribution, and bioavailability in the body; can contribute to oxidative stress, implicated in the pathogenesis of male infertility; and can inhibit DNA repair. On the other hand, Zn and Se are known to be essential for male reproductive function and can reduce the toxicity of Pb, Cd, and several other metals. Conclusion: The observed significant synergistic effect of blood Pb and blood Cd on increasing serum testosterone, and additive effect of a decrease in serum Se on increasing serum testosterone, may have implications on the initiation and development of prostate cancer because testosterone augments the progress of prostate cancer in its early stages.