Sunscreen may lower a man's chances of fathering a child, new research suggests. Danish researchers have found that some ingredients in American and European sunscreen impair sperm cell function.
After testing 29 of the 31 ultraviolet filters allowed in sunscreens sold in the U.S. and European Union, researchers from the University of Copenhagen found that some of the chemicals disrupted the calcium signaling of sperm cells. They noted that some of the ingredients seemed to have effects that mimic the female hormone progesterone.
"These results are of concern and might explain in part why unexplained infertility is so prevalent," said Dr. Niels Skakkebaek, the study's lead researcher and professor at the University of Copenhagen.
The researchers explained that sunscreen impairs sperm function by seeping through the skin and into the rest of the body. After analyzing urine and sperm samples, they found ultraviolet-filtering chemicals in almost all urine samples and some blood samples.
To examine how UV-filtering chemicals affect healthy sperm, the researchers tested sperm cells in a buffer solution that simulated the conditions in female fallopian tubes. Skakkebaek and his team wanted to concentrate on calcium signaling- particularly the sperm-specific calcium ion channel called CatSper. The researchers explained that the CatSper channel binds to the female hormone progesterone to control sperm cell fertilization functions like sperm motility.
The results revealed that 45 percent of the 29 UV filters tested in the study interfered with normal sperm function. The analysis revealed that 13 UV filters triggered a surge in the movement of calcium ions within sperm cells during binding with progesterone.
"This effect began at very low doses of the chemicals, below the levels of some UV filters found in people after whole-body application of sunscreens," said Skakkebaek.
The findings also revealed that nine of the 13 UV filters that impaired sperm function seemed to mimic the effects of progesterone, suggesting that UV filters disrupt the body's endocrine system.
The researchers noted that all of the UV filters tested in the study have been approved by the U.S. and European Union to be used in sunscreens.
"Our study suggests that regulatory agencies should have a closer look at the effects of UV filters on fertility before approval," Skakkebaek said.
The findings will be presented at the annual Endocrine Society conference in Boston, Mass., which will be held from April 1-4.