Sunscreen can render a man infertile by disrupting human sperm cells, a study has found.
Nearly half of the ingredients commonly used to block out ultra-violet light mimic the effects of the female hormone progesterone, which stops sperm cells functioning normally, researchers said.
The sunscreen lotion can enter the blood stream by being absorbed through the skin.
Niels Skakkebaek, a professor at the University of Copenhagen said the findings were worrying.
‘These results are of concern and might explain in part why unexplained infertility is so prevalent,' he said.
Almost half of the ingredients commonly used to block out UV light mimic the effects of the female hormone progesterone, which stops sperm cells from functioning normally, scientists at the University of Copenhagen have warned (file image)
Professor Skakkebaek and his colleagues tested 29 of the 31 UV filters allowed in sunscreens in the U.S. or the European Union (EU) on live, healthy human sperm cells, from fresh semen samples obtained from several healthy donors.
Nearly half of the UV filters acted as hormone disruptors – disrupting the sperm cells’ normal functioning.
To test the effects of the chemicals on sperm cells, the scientists placed the sperm in a solution that resembled the conditions in female fallopian tube
The researchers investigated a feature of sperm cells that is essential for their function known as calcium ion channeling.
They found a specific channel in a sperm cell which is a receptor for the female hormone progesterone.
When a sperm cell encounters progesterone, this leads to calcium ions surging into the sperm cell, which can stop them effectively fertilising an egg.
Of the sunscreens, 13 of the tested UV filters – 45 per cent – disrupted vital sperm cell function such as the movement of the sperm cell.
Professor Skakkebaek said: ‘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.
Of the 13 UV filters, nine of them mimicked the effect of progesterone.
Professor Skakkebaek is calling for clinical studies to investigate whether chemical UV filters affect human fertility.
The study suggests sunscreen, which gets into the bloodstream after being absorbed through the skin, could harm a man's fertility. Experts have called on regulatory agencies to take a closer look at the effects of UV filters on fertility before approval
He said: ‘Our study suggests that regulatory agencies should have a closer look at the effects of UV filters on fertility before approval.’
Some of the chemicals which have regulatory approval but have been found to disrupt sperm include: avobenzone – considered as one of the most important UV filters, homosalate, meradimate, octisalate (also known as octyl salicylate), octinoxate (or octyl methoxycinnamate), octocrylene, oxybenzone (also called benzophenone-3 or BP-3) and padimate.
As well as being common in in sunscreens they are also used in sunscreen-containing personal care products, such as makeup, moisturizers and lip balms.
Although the purpose of the chemical UV filters is to reduce the amount of the sun's UV rays getting through the skin by absorbing UV, some UV filters are rapidly absorbed through the skin, Skakkebaek said.
UV filter chemicals reportedly have been found in human blood samples and in 95 percent of urine samples in the U.S., Denmark and other countries.
Previous research has found that oxybenzone, a common ingredient in sunscreens, is toxic to coral reefs.
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