Some sunscreens may cause infertility, according to a Danish study presented on April 1 at the 98th annual meeting of Endocrine Society in Boston. The study reveals that many ultraviolet-filtering chemicals in these sunscreens interfere with normal sperm cell and progesterone functions.
University of Copenhagen professor and Copenhagen University Hospital in Rigshospitalet researcher Niels Skakkebaek points out that this may explain why unexplained infertility is so common. Apparently, some UV filters get absorbed through the skin rapidly, contaminating the body. Previous investigations have found these chemicals in blood samples and in 95 percent of urine samples.
The researchers examined the effects on 29 of the 31 US and European Union-approved UV filters on sperm cells. The sperm cells were taken from healthy human donors and were placed in a buffer solution that mimicked the fallopian tubes.
They looked into the calcium signalling, a signalling in the cell caused by an alteration in calcium ion concentration. According to the researchers, the movement of calcium ions within sperm cells through the cation channels of sperm (CatSper) is crucial for normal cell function.
CatSper is also necessary for male fertility and is the main sperm receptor for progesterone that activates the sperm to swim to the egg. When progesterone binds to CatSper, a temporary influx of calcium ions into the sperm cell occurs, causing sperm dysfunction.
Forty-five percent or 13 of the tested UV filters stimulated calcium ion influxes that prevented normal sperm cell function. These include the eight US-approved padimate O, avobenzone, octocrylene, homosalate, meradimate, octisalate or octyl salicylate, octinoxate or octyl methoxycinnamate and oxybenzone or benzophenone-3 or BP-3.
Moreover, of these 13 UV filters, nine imitated the effect of progesterone, directly activating the CatSper channel that stimulated the surge of calcium ion. Some have even affected the sperm’s ability to move through the female reproductive tract, which is also known as sperm motility.
These UV filters are also used in makeup, moisturizers and lip balms. Even applying a small amount of sunscreen can cause these effects.
Still, the researchers say that more investigations are needed. They recommend agencies responsible for regulating these chemicals to delve into their effects before approving these for public use.