Lead may impair male fertility

Lead remains in high levels in the environment and lead exposure may cause some cases of unexplained male infertility by impairing sperm function according to a new research. Lead is known to reduce fertility in animal models, but a direct link between lead exposures and human infertility has not yet been established. Although none of the men were exposed to high levels of lead on the job, there are many ways lead exposure can occur. Sources include water pipes containing lead, paints, ceramic glazes, pewter and some types of metal utensils. Lead seems to impair normal sperm function. Researchers at the North Shore-Long Island Jewish Research Institute in Manhasset, New York studied 140 couples who were trying to conceive through in vitro fertilization (IVF). Lead in seminal plasma was determined by atomic absorption spectroscopy. The more lead a man had in his semen, the lower the odds were that his partner would conceive. Additional testing, including measuring lead levels in sperm, may be a good idea for men who are infertile for unknown reasons. But researchers cautioned that the public should not get frightened that there is an epidemic of lead poisoning in men. Men in the study had normal levels of lead in the blood, but their semen contained elevated levels of the metal. The testis are often a storage depot for environmental exposures including lead. When the researchers took sperm from fertile men and exposed it to the metal, two out of three signs of healthy sperm function were abnormal. If an infertile man does turn out to have too much lead in his semen, it may be possible to lower lead by taking zinc supplements. Lead seems to compete with zinc in semen. As lead levels rise, zinc levels drop. However in about half of all couples who cannot conceive, male infertility is to blame and that in nearly half of these cases, the cause of male infertility is unknown.