WIKIMEDIAAdditives known as endocrine disrupting chemicals (EDCs) compromise male fertility by interfering with a membrane-bound calcium channel that normally controls motility of sperm cells, according to researchers in Germany and Denmark. EDCs are used in hundreds of household products—including toothpastes, sunscreens, cosmetics, plastic bottles, and toys—and scientists determined that they can cause fertility problems in previous studies. But a study published in the journal EMBO reports yesterday (May 12) is the first to posit a mechanism for how the chemical additives affect fertility in the human reproductive tract.
“For the first time, we have shown a direct link between exposure to endocrine disrupting chemicals from industrial products and adverse effects on human sperm function,” study coauthor and Copenhagen University Hospital researcher Niels Skakkebaek said in a statement.
Skakkebaek and his colleagues tested 96 EDCs and found that about a third of them disrupted the function of an ion channel, called CatSper, in the membranes of sperm cells in vitro. EDCs, at concentrations typical for bodily fluids, added to human sperm opened CatSper channels, causing calcium to rush into the cells. This increased concentration of calcium ions changed the swimming behavior of the sperm, triggering the premature release of digestive enzymes that sperm need to breach the outer layers of egg cells. EDCs also appeared to decrease sperm’s sensitivity to progesterone and prostaglandins, hormones released by egg cells to guide the swimming cells to their ultimate target. “Compare it with your GPS receiving abnormal signals,” Skakkebaek told CNN. “This may result in a wrong destination—read: the sperm may not reach the egg and fertilization may not occur.”
The European Commission is currently reviewing its policies on EDCs. Allan Pacey, a researcher at Sheffield University in the United Kingdom, told the Guardian that the new study is interesting, but should not, in isolation, change the advice that physicians give to their patients regarding EDCs. “Although sperm calcium changes may be seen in the laboratory, this is a long way removed from what might happen in living people,” he said.