![]() A camphor derivative that is also a broad UVA filter is terephthalyidene dicamphor sulfonic acid. Ĭamphor derivatives are not FDA-listed but are moderately effective UVB filters. It is a water-soluble compound commonly used in cosmetics for a lighter, less oily feel. Įnsulizole is a pure UVB filter and does nothing that affects UVA. When combined with other UV absorbers, it can increase the SPF formula. Octocrylene is a very safe chemical associated with a decreased likelihood of irritation, phototoxicity, and photoallergic potential. A water-soluble salicylate is trolamine salicylate. They function to decrease the photodegradation of other UV filters, such as oxybenzone and avobenzone. Two salicylates that are FDA listed are homosalate and octisalate. They are also used to increase the effect of other UVB filters. Salicylates are used in high concentrations as they are weak UVB absorbers. Octinaxate is not very photostable and degrades in the presence of sunlight after a short period. It is not as potent a UVB absorber as padimate O for this reason, other UVB absorbers are used in combination to increase the SPF. Octinoxate is the most commonly used UVB filter in the United States. Ĭinnamates have replaced PABA as the next most potent UVB absorber and include octinoxate (OMC) and cinoxate. Padimate O is the most commonly used PABA derivative it has a good safety profile and is an effective UVB filter. For this reason, it has limited use in sunscreen. PABA is a very effective UVB filter however, it was reportedly the most common photoallergen and contact allergen. Their use has declined due to para-aminobenzoic acid (PABA) sensitivity. Īminobenzoates are the most potent UVB absorber but do not absorb UVA. Broad-spectrum sunscreens absorb UV radiation from both the UVA and UVB portions. Uva radiation is divided into UVA I (340 to 400 nm) and UVA II (320 to 340nm). ![]() UVA filters do not cover the entire spectrum of UVA radiation. UVB filters absorb the entire spectrum of UVB radiation (290 to 320 nm). Chemical sunscreens consist of UVA and UVB blockers. The specific range of wavelength a sunscreen absorbs will vary. As the molecule returns to the ground state, it will release the lower energy of longer wavelengths. This structure allows high-energy UV rays to be absorbed, causing the molecule to achieve an excited state. Their mechanism of action is based on their chemical structure involving an aromatic compound conjugated with a carbonyl group. Ĭhemical sunscreens are known as organic sunscreens. Secondary factors include antioxidants, osmolytes, and DNA repair enzymes, which help to limit skin damage by disturbing the photochemical cascade that occurs with UV sunlight. Primary factors are sunscreens these include physical barriers that reflect and scatter light and chemical barriers that absorb light. Photoprotection involves both primary and secondary protective factors. It causes pyrimidine dimer mutations, which are associated with nonmelanoma skin cancers. UVB causes sunburn and DNA strand breaks. UVA increases the number of inflammatory cells in the dermis and decreases the number of antigen-presenting cells. It penetrates deep into the skin layer and produces free radical oxygen species, indirectly damaging DNA. UVA is associated with aging and pigmentation. For this reason, the depletion of the ozone layer increases UV transmission. The ozone layer absorbs 100% of UVC, 90% of UVB, and a minimal amount of UVA. There are three types of UV radiation: UVC, UVB, and UVA. UV radiation has an immunosuppressive effect on the antigen-presenting cells within the epidermis and contributes to the likelihood of skin cancer. UV radiation greatly affects the skin, causing aging, sunburns, precancerous and cancerous lesions, and immunosuppression. SPF-15 or higher is the recommended blocking strength, and manufacturers can label it as reducing the risk of skin cancer and early skin aging. Currently, 16 UV filters are listed, 14 organic filters, and two nonorganic filters, including zinc oxide and titanium dioxide. The FDA has changed its guidelines to address broad-spectrum sunscreen use, which involves UVA and UVB coverage water resistance, to indicate the time duration the sunscreen is effective and sun protection factor (SPF). The FDA regulates sunscreen as an over-the-counter medication. Recurrent and severe sunburns are a risk factor for nonmelanoma skin cancer. Photoaging can manifest as sagging and wrinkling, while photocarcinogenesis is due to the damage of cells and DNA. The damaging effects of UV radiation include photoaging and photocarcinogenesis. Photoprotection includes sunscreens, clothing, hats, makeup, sunglasses, and windshields. Photoprotection is indicated for the reduction of ultraviolet (UV) radiation-induced skin damage and skin cancers.
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