Why too much sun cream can be dangerous

Screw it on, apply sun cream, feel safe - this is a mechanism that has crept in over the past years and decades. Sun creams with a sun protection factor (SPF) of less than 6 are no longer available on the market. Consumers are increasingly turning to creams with SPF 30 and above.

Dermatologists, pharmacists and the skin cancer lobby have raised awareness of the need to protect our skin. After all, Switzerland is one of the countries most affected by skin cancer, with around 2,000 new cases of malignant melanoma and an estimated 15,000 cases of fair skin cancer diagnosed every year.

Many young people assume that they only need to apply sun cream and can then safely wear off-the-shoulder tops.

Sun protection is the most important preventive measure. Especially for children and young people. After all, the extent of our risk of skin cancer is already decided at a young age. But there are also critical voices against sun cream.

On the one hand, it conveys a deceptive sense of security: the effect of moisturising is often overestimated. This was discovered by the University of Basel in a survey of young people in 2012. For many, applying sun cream was taken for granted - but going into the shade and covering up was not. This explains why applying sun cream as a matter of course did not reduce the number of sunburns.

More than half of all pupils stated that they had suffered at least one sunburn in the previous year. Many apparently assume that all they have to do is apply sun cream and then they can safely wear off-the-shoulder tops and work on a nice tan in the sun.

And misjudgement is not the only danger from the sun cream tube: If you google the terms sun cream and danger, you can quickly get the feeling that we are putting pure poison on our skin, which is even more likely to cause cancer, make our skin swell up with allergies and upset our hormone levels.

Sun creams are chemical agents that have an effect on the body.

Nathalie von Götz, Senior Scientist ETH Zurich

Alternative health websites advise people to apply sesame or coconut oil instead. However, they do not give any predictions as to how long you can then lie in the sun. The good news first: many of the substances that are suspected of being harmful to health are banned in Switzerland anyway. And at least products for sensitive skin and children's skin largely dispense with allergy-causing perfumes.

Nevertheless, sun cream remains under discussion. As recently as spring 2019, another US study (published in the specialist journal Jama)showed that the ingredients enter the bloodstream faster and in higher concentrations than previously assumed. Further studies are to follow.

«Sun cream definitely does more good than harm,» says Natalie von Götz, senior scientist and lecturer at the Institute of Chemical and Bioengineering at ETH Zurich. In 2015, she investigated how much sun cream the Swiss use and whether chemical UV filters are applied in questionable quantities. She found that the Swiss apply too much sun cream to themselves and, in particular, their children, using substances of concern.

Of all things, products for children are affected

The study found two substances that could become a problem in the quantities used: Octocrylene is found in many sun creams available here and can trigger allergies. It is difficult to determine how many people react to it, as only a few people are tested for allergies.

«When skin reactions occur after sunbathing, many people think of a sun allergy, but not that it could also be an allergic reaction to the sun cream.» Nevertheless, more and more dermatologists are reporting allergies to octocrylene.

Shade alone does not protect against sunburn. Between 50 and 90 per cent of dangerous UV rays still reach the skin.

The second controversial substance bears the monstrous name ethylhexyl methoxycinnamate, or EHMC for short. Young children, of all people, are the most exposed to this substance because it is found in some sun protection products that are specifically advertised for children. The substance is also frequently used in cosmetics and face creams with a sun protection factor - possibly simply because the substance is cheaper than other UV filters.

However, EHMC is hormone-active - in other words, it can have an impact on hormone balance. «If this gets mixed up during the development of the embryo, this can result in undescended testicles in small children and premature onset of puberty, for example,» says von Götz.

So far, however, there has been insufficient research into how and how much of the controversial substances from the creams enter the metabolism via the skin and what happens to the substances there. The ETH Zurich research group therefore recommends further investigations and possibly also lowering the threshold values for the substances.

Meanwhile, should parents avoid products containing octocrylene and EHMC? Von Götz is cautious and does not want to «demonise» substances in principle. She herself uses a product for herself and her children that also contains the potentially allergenic substance octocrylene. «But I keep my distance and am aware that sun creams are chemicals that have an effect on the body - you should always bear that in mind when it comes to cosmetics,» she says. However, von Götz clearly advises against simply applying sun cream prophylactically to children every day in summer (see tips below).

Alternatives to chemical sun creams

If this is too vague for you and you prefer to do without chemicals, there are of course alternatives. Mechanical sun protection is recommended from all sides - i.e. shielding yourself from the sun with clothing such as hats, special sun protection shirts and sun sails. Shade alone does not protect against sunburn. Depending on which study you consult, 50 to 90 per cent of dangerous UV rays still reach the skin.

In Switzerland, sunscreens containing the physical or mineral sunscreen filter titanium dioxide are also available on the market. The substance is natural and offers good sun protection, but the cream is often difficult to absorb - a white and sticky film remains on the skin. In addition, some people are allergic to the mineral filters.

«An alternative is child protection cream with nano titanium dioxide,» says von Götz. This is easier to spread and is absorbed more quickly. However, nanotechnology is no longer natural and again has many critics. Von Götz: «So far, I am not aware of any study that says that the absorption of nanoparticles through intact skin is critical.» However, caution is advised with wounds or if the particles could be inhaled.

Von Götz strongly advises against experimenting with sesame oil and coconut oil - she is not sure how they are supposed to provide sun protection. Another natural protection against the sun is the skin's own melanin. In other words, a healthy tan. But achieving this is a balancing act between harm and benefit.

This article was written in 2017 and has been updated with new findings.