Benzophenones -5

Synthetic UV absorber; protects skin or hair from harmful UV radiation. Also protects cosmetic products from damage by UV light.

Occurrence in cosmetics: as UV filter in sunscreens and cosmetics with UV protection. As UV absorber to protect e.g. fragrances, dyes and active ingredients in the product and plastics in the product packaging.

Occurrence in other products: as photoinitiator in UV-curing applications, such as inks and coatings in the printing industry.

Organic light protection filters are all those UV filters whose effect is not exclusively based on the inorganic, physically active substances titanium dioxide or zinc oxide. Organic, also known as chemical UV filters, are photoactive substances that are able to absorb light quanta in a certain wavelength range (ultraviolet radiation in the range of about 280 to 400 nm = ultraviolet radiation = UVB/UVA spectrum). The absorbed UV is then released as thermal energy without penetrating the skin. In this reversible photoisomerization, the energy of the absorbed photon must correspond to the energy required to lift an electron in the molecule of the filter substance from a lower to a higher orbit. In order to protect over the entire width of the wavelengths relevant to humans from 290 to 400 nm, several chemical filters with different absorption maxima are usually combined. With a suitable combination of organic and physical filters, the content of organic filters can also be reduced with the same UV protection. This is desirable, since especially photounstable organic UV filters can cause phototoxic and photoallergic reactions depending on their concentration in the finished product.

1. Nohynek GJ et al (2001) Benefit and risk of organic ultraviolet filters. Regul. Toxicol. Pharmacol 33: 285-299