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Why should you avoid reusing sunscreen year after year?

When exposed to the sun, it is strongly recommended to protect yourself with sunscreen. However, it is not uncommon for a tube of cream to "survive" from year to year. The question then arises of its reuse. In reality, it is absolutely necessary to avoid it and to prefer the purchase of a new tube.

A bad idea

This is vacation time when we pack our bags. That's when the discovery of a tube of sunscreen from last year asks:should I take this tube? After all, reusing this cream would indeed not waste the product that remains. This will also avoid generating polluting waste. Quoted by the daily Metro, Christine Lafforgue, president of the French Society of Cosmetology, however, believes that this is a bad idea.

Remember that sunscreen contains molecules that absorb wavelengths of the ultraviolet spectrum (UV). However, UV rays can cause skin cancers such as melanomas. It is also necessary to distinguish between UVB, which mainly causes sunburn, and UVA, which promotes premature aging of the skin.

Why should you avoid reusing sunscreen year after year?

In the trash at the end of the holidays!

The fact is that sunscreen creates a protective film on the surface of the skin. However, molecules that absorb UV rays have conjugated double bonds. This term relates to the bonds between atoms of the molecule, stronger than single bonds. Indeed, an atom is then associated with a second by a double bond. This second atom is itself linked to a third by a single bond. Then this third atom is linked to a fourth by a double bond and so on.

In addition, the regulations provide for 28 filters in the composition of sunscreens. However, 26 of them are organic and 2 others are mineral. The former absorb UV and the latter reflect it. In addition, the composition of the creams is a kind of mayonnaise also incorporating water, oil, preservatives and sometimes alcohol.

Christine Lafforgue reminds that no sunscreen is intended to be reused the following year. Several factors can explain the fact that this kind of product cannot be stored for so long. These include exposure to heat or again the successive openings of the tube. In other words, an unfinished tube of sunscreen at the end of the holidays should simply be thrown in the trash. Otherwise, the protection against the sun's rays will no longer be optimal.