# Recent Trends on UV filters
## 3 Results  
### Usage Frequency of UV Filters in Sunscreens for Adults and Children  
Among the 28 UV filters approved by Regulation (EC) n\({}^{\circ}\) 1223/2009, 24 were identified in the market study performed. Through the analysis of adult sunscreens, a higher usage of organic UV filters was observed (20 of the 24, Figure 1) when compared to inorganic filters, including both nano and non-nano forms (4 of the 24, Figure 1). Avobenzene (BMDBM), octocrylene (OC), and bis-ethylhexyloxyphenyl methoxyphenyl triazine (Tinosorb S\({}^{\text{S}}\)) were the three most frequently used UV filters with percentages that varied between 45% and 75%, all belonging to the organic UV filters category (Figure 1). Avobenzene, also known as BMDBM, is widely used in adult sunscreens and had a usage frequency of 73.9%. This UV filter absorbs UVA radiation, conferring protection against one of the most harmful radiations that is directly associated with skin photoaging and indirect damage to DNA through stimulation of the production of reactive species, inducing an oxidative stress process [24]. Octocrylene (51.7%) and bis-ethylhexylophenol methoxyphenyl triazine (47.5%), which absorb UVB and UVA/UVB radiation, respectively, were also frequently used in adult sunscreen formulations. Ethlyhexyl triazone (EHT) (38.0%) and ethylhexyl salicive (EHS) (35.9%), ranked fourth and fifth, are also UV filters with the ability to absorb UVB radiation. Photostability is critical for the effective photoprotective action of the UV filters. Nevertheless, some currently used UV filters have demonstrated low photostability [17]. Avobenzene is photounstable and suffers photoisomerization and/ or photodegradation when exposed to UVR [25]. Phenacyl and benzoyl radicals are the main photodegradation products formed; however, their combination could generate more reactive and toxic species for human beings and the environment [25,26], thus losing its photoprotective action [25]. Additionally, octocrylene was recently reported for its transformation through retro-aldol condensation into a phototoxic benzophenone derivative [27]. Interestingly, some UV filters could act as photostabilizers. Octocrylene and bis-ethylhexyloxyphenyl methochoxyphenyl triazine filters are examples of UV filters that possess dual activity, acting as photoprotective agents against UV radiation but also as photostabilizers of other filters, such as avobenzene [28]. Octocrylene has been reported to prevent around 50% of avobenzene's degradation after 1 h of UVR exposure [29]. It is important to highlight that these three UV filters exhibit a high percentage of use, probably not only for their photoprotective activity, but also for the advantageous effects when combined together. Additionally, the combination of avobenzene with octocrylene could amplify photoprotective action towards both regions of the UV spectrum (UVA and UVB), ensuring broad-spectrum action. Bisethylhexyloxyphenol methoxyphenyl triazine (broad-spectrum UV filter) and ethylhexyl1 triazone (strong UVB absorber) appear in third and fourth, respectively. These filters were two of the last five UV filters approved by European regulations and have been observed exhibiting effective protective action against UV radiation and good photostability [30]. This has led to these filters gaining special attention from cosmetic industries, pushing the demand for expanded production capacity [31]. Regarding inorganic UV filters, nano-sized TiO\({}_{2}\) is much more frequent in adult sunscreens than non-nano form TiO\({}_{2}\), and the latter is the inorganic UV filter with the highest usage frequency (24.5%). The approved use of the nano forms of certain UV filters was only observed after 2010. In 2014, the first nano UV filter, tris-biphenyl triazine, was approved for use in the EU [14]. Zinc oxide (2016) and nano-sized methylene bis-benzotriazoyl tetramethyl butylphenol (MBBT) (2018) have also been approved in recent years [32; 33].