Male infertility and environmental exposure to lead and cadmium.
Humans are exposed occupationally and environmentally to metal aerosols including lead (Pb2+) and cadmium (Cd2+). These toxicants accumulate in male reproductive organs. Epidemiological studies have been equivocal about effects of Pb2+ and Cd2+ on hormone concentrations, male fertility and sperm parameters. Comparison of Pb2+ and Cd2+ concentrations in fertile and infertile men are problematic. Problem areas include failure to control confounding variables, but genetic polymorphisms as in somatic diseases may modulate Pb2+ and Cd2+ damage. Multiple calcium (Ca2+) and potassium (K+) channel isoforms have been identified in human testes and spermatozoa. These Ca2+ and K+ channels are involved in early events of acrosome reactions. Ca2+ channel are susceptible to Cd2+ poisoning and K+ channels to Pb2+. These channels offer entry paths for metallic toxicants into mature spermatozoa. Ion channel polymorphisms may cause differential sensitivities to Cd2+ and Pb2+, explaining in part prospective blinded studies showing high Cd2+ in varicocele-related human infertility and high Pb2+ in unexplained infertility. In both forms of male infertility the ability to undergo an acrosome reaction decreases. Reverse transcriptase-polymerase chain reaction assays for Ca2+ and K+ channel isoforms may identify susceptibility subgroups with lower resistance to environmental exposures.
Benoff
S
S
Department of Obstetrics and Gynecology, North Shore University Hospital-New York University School of Medicine, Manhasset 11032, USA. sbenoff@nshs.edu
Jacob
A
A
Hurley
I R
IR
D002104:Cadmium / Q000032:analysis / Q000494:pharmacology; D002105:Cadmium Poisoning; D004781:Environmental Exposure; D006801:Humans; D007248:Infertility, Male / Q000139:chemically induced*; D007473:Ion Channels / Q000187:drug effects; D007854:Lead / Q000032:analysis / Q000494:pharmacology; D007855:Lead Poisoning; D008297:Male; D012661:Semen / Q000737:chemistry
D007473:Ion Channels; D002104:Cadmium; D007854:Lead