100 SKIN PROTECTION
dioxide and nano zinc oxide, which reflect UV radiation, are more stable and therefore are becoming more widely used. Avobenzone (butyl methoxydibenzoyl methane) is the most commonly used organic UVA filter, but has low stability and is susceptible to crystallisation. UVB- absorbing filters such as octocrylene and oxybenzone, or even some antioxidants, such as quercetin, can help to stabilise avobenzone. However other UVB filters contribute to its degradation. Ethylhexyl methoxycinnamate (OMC) is a widely used UVB organic filter as it provides good protection, has a light skin-feel, and is low in colour and odour. While OMC has its positives, it also destabilises avobenzone and so it is not recommended to use these together, as it can result in formulations that are not photostable. This
stabilising/destabilising action comes from the fact that when avobenzone absorbs a photon of UV light, it is excited to a triplet energy state. While stabilising substances such as octocrylene help quench avobenzone to return it to its ground energy state, ethylhexyl methoxycinnamate reacts with high energy avobenzone to form products that do not function as UV filters.8 It has also been shown that avobenzone degrades when used with untreated titanium dioxide and zinc oxide. The FDA has banned the use of these inorganic filters with avobenzone for precisely this reason.9 Encapsulating avobenzone can be beneficial, as it separates the filter from the environment and the skin, minimising the risk of degradation and irritation. Encapsulation in polymer microspheres effectively protects avobenzone, minimising interaction with materials such as ethylhexyl methoxycinnamate, improving photostability while also improving the skin- feel.10-13 Formulators of natural products tend to
PERSONAL CARE EUROPE
prefer using solely inorganic filters for sun protection, and non-nano filters where possible, due to concerns surrounding the potential effects of nano materials on human and environmental safety. Non-nano filters generally provide poorer sun protection and cause more whitening than nano filters as the larger particle size means the spectrum of light they reflect is shifted away from the UVB region. Environmental considerations are also becoming more important in consumers’ choice of sun care products. The bleaching of the Great Barrier Reef has led to research on the impact of UV filters on coral. As a result, Hawaii has banned the common UVB organic filters, oxybenzone and ethylhexyl methoxycinnamate, and a ‘reef-safe’ claim has propagated in the sector, although this claim is poorly defined. The issue of reef safety has so far been focused on organic UV filters but there is evidence to show that untreated titanium dioxide and zinc oxide also bleach coral.14
Many of the drawbacks of inorganic
sunscreens can be countered to a degree through surface modifications. Surface treatments help to prevent agglomeration, and so reduce whitening and improve skin- feel. They also reduce interactions between the inorganic filters and other materials, improving compatibility with avobenzone and reducing the impact on coral bleaching.
Beyond UV filters, the choice of emollients in the formulation is also critical to performance. It is essential that organic UV filters remain fully solubilised as crystallisation or separation will lead to a reduction in protection. Esters are a fantastic option as they tend to be good solubilisers of organic UV filters and also have a lighter skin-feel than traditional oils. UV filters tend to have a greasy or heavy skin-feel, but this can be improved through
the use of dry, light esters such as octyldodecyl neopentanoate, methylheptyl isostearate, or shea butter ethyl esters. As previously discussed, silicones are often used to formulate light W/O creams to counter the unpleasant feel of UV filters. However they tend to have poor compatibility with organic UV filters, which limits their use in some formulations. When using silicones, diphenylsiloxy phenyl trimethicone can be used to improve compatibility between silicones and organic filters due to their phenyl groups.
High SPF products Several brands are competing in the development of creams with ever- increasing SPF, and we can see products on the market with SPF 70, 90, and even 100! Many wonder whether such high protection is necessary, and if it could even be detrimental. Properly applied sunscreen with SPF 50 should block 98% of UVB rays, and when doubling the SPF to 100, the protection from UVB rays only raises to 99%.10
UVB radiation is the main cause of
sunburn, but UVA penetrates deeper into the dermis and is more difficult to block. Exposure to both UVA and UVB causes the formation of harmful free radicals in the skin and is associated with a greater risk of developing cancer. It is therefore not only important to look for products with a high SPF, but also to look at the degree of UVA protection a product provides. In the EU, products must have a UVA / UVB protection ratio of at least 1/3. Most sun care products emphasise the importance of frequent application, but ‘once-a-day’ products have become very popular and are the source of some controversy. Anti-cancer organisations are concerned that such products can give a false sense of security that puts consumers at greater risk of sunburn. The submission of such declarations
April 2019
Page 1 |
Page 2 |
Page 3 |
Page 4 |
Page 5 |
Page 6 |
Page 7 |
Page 8 |
Page 9 |
Page 10 |
Page 11 |
Page 12 |
Page 13 |
Page 14 |
Page 15 |
Page 16 |
Page 17 |
Page 18 |
Page 19 |
Page 20 |
Page 21 |
Page 22 |
Page 23 |
Page 24 |
Page 25 |
Page 26 |
Page 27 |
Page 28 |
Page 29 |
Page 30 |
Page 31 |
Page 32 |
Page 33 |
Page 34 |
Page 35 |
Page 36 |
Page 37 |
Page 38 |
Page 39 |
Page 40 |
Page 41 |
Page 42 |
Page 43 |
Page 44 |
Page 45 |
Page 46 |
Page 47 |
Page 48 |
Page 49 |
Page 50 |
Page 51 |
Page 52 |
Page 53 |
Page 54 |
Page 55 |
Page 56 |
Page 57 |
Page 58 |
Page 59 |
Page 60 |
Page 61 |
Page 62 |
Page 63 |
Page 64 |
Page 65 |
Page 66 |
Page 67 |
Page 68 |
Page 69 |
Page 70 |
Page 71 |
Page 72 |
Page 73 |
Page 74 |
Page 75 |
Page 76 |
Page 77 |
Page 78 |
Page 79 |
Page 80 |
Page 81 |
Page 82 |
Page 83 |
Page 84 |
Page 85 |
Page 86 |
Page 87 |
Page 88 |
Page 89 |
Page 90 |
Page 91 |
Page 92 |
Page 93 |
Page 94 |
Page 95 |
Page 96 |
Page 97 |
Page 98 |
Page 99 |
Page 100 |
Page 101 |
Page 102 |
Page 103 |
Page 104 |
Page 105 |
Page 106 |
Page 107 |
Page 108 |
Page 109 |
Page 110 |
Page 111 |
Page 112 |
Page 113 |
Page 114 |
Page 115 |
Page 116 |
Page 117 |
Page 118 |
Page 119 |
Page 120 |
Page 121 |
Page 122 |
Page 123 |
Page 124 |
Page 125 |
Page 126 |
Page 127 |
Page 128 |
Page 129 |
Page 130 |
Page 131 |
Page 132 |
Page 133 |
Page 134 |
Page 135 |
Page 136 |
Page 137 |
Page 138 |
Page 139 |
Page 140 |
Page 141 |
Page 142 |
Page 143 |
Page 144 |
Page 145 |
Page 146 |
Page 147 |
Page 148 |
Page 149 |
Page 150 |
Page 151 |
Page 152 |
Page 153 |
Page 154 |
Page 155 |
Page 156 |
Page 157 |
Page 158 |
Page 159 |
Page 160 |
Page 161 |
Page 162 |
Page 163 |
Page 164 |
Page 165 |
Page 166 |
Page 167 |
Page 168 |
Page 169 |
Page 170 |
Page 171 |
Page 172 |
Page 173 |
Page 174 |
Page 175 |
Page 176 |
Page 177 |
Page 178 |
Page 179 |
Page 180 |
Page 181 |
Page 182 |
Page 183 |
Page 184 |
Page 185 |
Page 186 |
Page 187 |
Page 188
