There is evidence that some sunscreen ingredients are endocrine disruptors that are directly interfering with human sperm cells, at least in test tubes. It is understood that around half the ingredients in commonly-used sunscreen that block UV light mimic the female hormone progesterone, stopping sperm cells from functioning normally on contact.
UV filters are rapidly absorbed through the skin, and have been found in blood and urine samples. Many personal care products contain the fertility-damaging ingredients (list below), like lip balms, make-up and moisturisers.
Is sunscreen causing a drop in male fertility in Australia and the world?
Fertility rates amongst men are reportedly dropping at an alarming rate, without a cause having been found. Perhaps sunscreen is playing a role, particularly in Australia where the ozone layer is thinner than most other parts of the world and sunscreen is a major weapon against skin damage and skin cancers.
Sunscreen may be the missing link in unexplained male infertility, researchers at the University of Copenhagen reported at the 98th annual meeting of the Endocrine Society in Boston, USA (April 2016). The results are not yet published.
A professor on the research team that made the findings from the university, Niels Skakkebaek, said the findings were worrying.
Twenty-nine of 31 known sunscreen UV filters in sunscreen found in the United States and Europe were tested on live, healthy human sperm cells from fresh semen samples from healthy donors. Almost half of the UV filters acted as hormone disruptors, causing malfunctions in the sperm cell. The experiments were performed in a solution that resembles the female fallopian tubes, where human conception takes place.
How exactly does the dysfunction occur in the sperm cell?
A feature of sperm cells is what’s known as calcium ion channelling, with a specific channel in a sperm cell being a receptor for progesterone. Men do produce some progesterone, but it is considered a predominantly female hormone. When the sperm cells encountered progesterone, the calcium ion surges in the sperm cell, potentially stopping it from effectively fertilising an egg.
Out of all tested sunscreens, 13 of the UV filters – 45 per cent – disrupted sperm cell function in this way, negatively impacting some sperm cell functions like motility (ability to move). The negative effects were present even at low levels of the chemicals, below the levels of some UV filters found in the blood of those who have applied a full body of sunscreen. Nine out of 13 UV filters mimicked the effect of progesterone.
The researchers are saying that before approving sunscreens, their impact on sperm cells should be tested by regulatory bodies.
Approved chemicals in sunscreen that were found to disrupt sperm in vitro:
- Octisalate (or octyl salicylate)
- Octinoxate (or octyl methoxycinnamate)
- Oxybenzone (or benzophenone-3 or BP-3, known to be toxic to coral reefs)
Mixed messages about sunscreen – how to mitigate the risks of interrupting sperm
If you are in the process of trying to conceive, your sunscreen use needs to be discussed with your dermatologist to find a sunscreen that doesn’t contain possible sperm-altering ingredients, or use the list above to seek out safe sunscreens.