Sunscreen is used to tame the risk of cancer. However, if used incorrectly, it can have the opposite effect. Durability plays an important role here.
Munich – Most people will know it: At home there are several tubes of sunscreen that were opened at some point and used up successively over several years.
If some experts are to be believed, this approach is problematic – and in the worst case can cause cancer. Dermatologist Professor Eckhard Breitbart advises that when in doubt, you shouldn’t rub yourself in the sunscreen you used last summer. The doctor appeals to buy a new tube of sunscreen in the supermarket or drugstore.
Sunscreen: what mistakes you should absolutely avoid
The expert from the German Cancer Aid and Chairman of the Working Group on Dermatological Prevention (ADP) explains why: Oxygen leads to oxidation – and this in turn means that ingredients change over a longer period of time. As a result, the UV protection for skin care can no longer be maintained. Breitbart explains: “Substances that are produced could well be carcinogenic.”
So far, there is no “proper evidence” for this thesis. However, a study by French and American scientists published in 2021 lists evidence: According to this, benzophenones have formed over time in creams with the UV protection filter octocrylene. And these are considered by experts to be potentially carcinogenic.
How long can a tube of sunscreen be used after opening? This is usually written on the packaging: The corresponding symbol is an open can with the information “12 M” in it, for example. That stands for twelve months. However, you don’t necessarily have to dispose of it afterwards, because there is one important point to consider: that the sunscreen is not often exposed to direct sunlight! Because that extends the shelf life:
Sunscreen still good? Evidence of how to recognize this
Incidentally, how you can tell whether you can still use sunscreen that has been opened: Check whether the skin care product looks different, smells different or the consistency has changed. For example, if there is an oily film or the sunscreen smells rancid, the sunscreen may not have been stored dry and cool enough.
In order not to lose track of when the sunscreen was opened, you can do a recommended thing: write the date of opening on the tube with a waterproof felt pen!
An MHD is often not noted on the skin care products. Sun creams (for comparison) do not always have a best-before date. If it does, and if this has been exceeded, the product should generally no longer be used. At least that’s what Professor Breitbart advises – even if they’re still unopened. But is the thesis tenable?
Sunscreen and shelf life: what to consider when it comes to the expiry date
According to scientists, consumers can apply the following maxim: The shelf life is usually 30 months from the date of manufacture. According to the Federal Office for Consumer Protection and Food Safety, cosmetic products in the European Union only have to have a best-before date if they do not have a shelf life of more than 30 months.
According to the sustainability portal Utopia.de Incidentally, there is another way to use sunscreen for longer: certified natural cosmetics. Octocrylene is a chemical UV filter, whereas mineral filters are used in natural cosmetics. For this reason, the use of organic mineral sunscreens is a advisable course of action.
UV rays are also an invisible danger: they accelerate sunburn and skin cancer. When things get tough. (PF with dpa)
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