Sunscreens protection factor

Diffey BL, Robson J. A new substrate to measure sunscreen protection factors throughout the ultraviolet spectrum. J Soc Cosmet Chem 1989 40 127-133. 

Sun protective factor Sunroof laminates Sunscreen agents Sunscreen products Sunscreens... 

In vitro absorption-spectrophotometry techniques are available to assess a sunscreen s efficacy, but the preferred methods are in vivo procedures in which a small body site is irradiated with the desired wavelengths for different periods in the presence or absence of a uv protectant. Procedures vary from country to country to determine the incremental timing of the exposure that ultimately allows quantification via sun protective factor (SPE). In the United States, sunscreen preparations are considered OTC dmg products, and the SPE must be specified (54). Even in countries that do not identify these products as dmgs, SPE labeling has become customary. 

Patients with melasma (Eig. 2.3) applied topical sunscreens (sun protection factor 15) and 10% glycolic acid lotion at night for 2 weeks. They were then treated with 50% glycolic acid facial peels once a month for 3 consecutive months. At regular intervals and at the end of the follow-up period (3 months) after the last peel, the degree of improvement in pigmentation was assessed by measuring MASl (Melasma Area and Severity Index) [11]. 

Twice a day moisturizing creams and UVB-UVA sunscreen (with a sun protection factor [SPF] of at least 15)... 

Use of sunscreen daily that is applied to all sun-exposed skin. Use of sunscreen with sun protection factor (SPF) 30 or... 

Avoid skin trauma. Sunburns can induce a flare-up of psoriasis. Sunscreens with a sun protection factor of at least 15 should be routinely used when outdoors often a sun protection factor of 30 is recommended. Avoid scratching the skin, which could lead to excoriations and exacerbate psoriasis. Loose-fitting cotton garments should be worn to minimize skin irritation. 

Pharmacists should tell their sun-deprived, fairskinned patrons not to spend more than 15-20 minutes in the mid-day sun (10 00 a.m. to 3 00 p.m.) on first exposure when traveling to vacation spots such as Florida [18]. This is ample, safe exposure to initiate the tanning response in those who are able to tan. Exposures can be increased incrementally by 15 minutes a day until a 45-minute tolerance is developed, which is generally an adequate level of sun protection in conjunction with the use of sunscreens. It should be obvious that dark-skinned people are already heavily pigmented and thus far less susceptible to burning. Other individuals don t tan at all and must apply sunscreens with high protection factors before sun bathing. 

These chemicals act much as the active ingredients in our sunscreens but have larger sun-protection factors. A project is currently under way to develop and market this discovery as a powerful new sunscreen. 

Q81 An ultrablock sunscreen preparation always has a sun protection factor of 30. Sunscreen preparations protect the skin from the damage associated with ultraviolet A (UVA). 

Sunscreen preparations tend to contain substances that protect the skin against sunburn caused by ultraviolet B (UVB) rays. UVA rays are associated v/ith long-term skin damage. Sunscreen preparations contain a variety of sun protection factors but not necessarily a factor of 30. 

The frequency of application of sunscreen is guided by the SPF (sun protection factor) of the preparation. This derived value is the ratio of the time of ultraviolet exposure that causes erythema with the sunscreen to the time that causes erythema without the sunscreen. The higher the SPF, the less frequent the needed application of sunscreen. SPFs of available preparations vary from 2 to 50. 

The sun protection factor (SPF) of a given sunscreen is a measure of its effectiveness in absorbing erythrogenic ultraviolet light. It is determined by measuring the minimal erythema dose with and without the sunscreen in a group of normal people. The ratio of the minimal erythema dose with sunscreen to the minimal erythema dose without sunscreen is the SPF. Fair-skinned individuals who sunburn easily are advised to use a product with an SPF of 15 or greater. 

Commercial sunscreens are given an SPF rating (sun protection factor), according to the amount of sunscreen present. The higher the number, the greater the protection. 

In the United States, sunscreens are classified as over-the-counter (OTC) drugs (2) hence, the ICH guideline is applicable. The requirement should then be to demonstrate that the product has the potential to protect human skin prior to application. This can be achieved analytically, e.g., utilizing UV absorption measurements or high-performance liquid chromatography (HPLC) (3), or more appropriately by an in vitro determination of its protective efficacy, e.g., sun-protection factor (SPF), UV-A protection factor (PF y ) or critical wavelength / (4-6). 

The first photostability measurements performed on cosmetic UV filters were carried out, probably in the 1930s, by Kunz (9). He prepared dilute solutions of UV filters in (cosmetic) solvents, exposed them to artificial UV radiation and recorded the changes in their UV absorption profile before and after exposure. At that time, the term, "sun-protection factor," was unknown and there was no standard methodology to evaluate the protective potential of a sunscreen on human skin. Hence, the behavior of the filter was used as a surrogate for a protection assessment. 

The performance of a sunscreen is expressed as the sun protective factor (SPF) which refers to UVB (UVA is more troublesome to measure and the protection is indicated by a star rating system with 4 stars providing the greatest). A SPF of 10 means that the dose of UVB required to cause erythema must be 10 times greater on protected than on unprotected skin. The SPF should be interpreted only as a rough guide consumer use is more haphazard and less liberal amoimts are applied to the skin in practice. Sunscreens should protect against both UVB and UVA. Absorbent and reflectant... 

The Sun Protection Factor (SPF) is the ratio of the amount of UVB radiation that is just enough to produce sunburn on protected skin to the amount that will produce the same effect on unprotected skin. For example, skin protected by a sunscreen with an SPF of 10 should be able to withstand a given intensity of UVB rays for 10 times as long as unprotected skin before burning. As no assessment of UVA protection is included, the SPF should not be used as the basis for recommending a sunscreen to a patient who is sensitive to UVA. 

Sunscreens are currently categorised eis cosmetics. Companies are encouraged to market only sunscreens that comply with the Australian/New Zealand Standard AS/NZS 2604 1998 Sunscreen Products. Evaluation and Classification . Com-pemies marketing sunscreens should have evidence to support the sun protection factor (SPF) and broad spectrum protection claimed. Sunscreens may become controlled as therapeutic products under the proposed Healthcare and Therapeutic Products Bill, though future legislation may simply formalise compliance with the Australian/New Zealand Standard. 

SPF is the ratio of the length of time of solar radiation exposure required for the skin to show redness (erythema) with and without protection. The term SPF or UPF (ultraviolet protection factor) has been introduced such that a garment of UPF 15 will provide the same amount of protection against solar ultraviolet radiation as a sunscreen of SPF 15. Garments with a UPF value of 20-29 offer high protection (UVR transmission 5.0-3.3%). A UPF value of 30-40 (UVR transmission 3.3-2.5%) offers very high protection and a UPF value of 40 + offers maximum protection with a UVR transmission of 2.5%. 

It is, however, UV-B Sunscreen agent which is more critical from skin protection point of view. Several UV-B Sunscreen agents have been introduced having various degrees of sun protection factor and effectiveness to the skin ... 

Education and re-education about the importance of sun protection has the potential to help decrease the rising incidence of this disease. Historically, patients have been counseled that the risk of skin cancer can be limited by the use of sunscreens with a sun protection factor (SPF) of 15 or greater. It is important to include counseling about the appropriate use of sunscreens to optimize benefits from these products. One study noted that most consumers typically... 

It pays to be a careful reader of labels. Here s a bint from Ms. Toyag, wbo bos formulated cosmetics for more tbon 20 years. Many cosmetic companies find it is o good selling point to odd sunscreen to tbeir products. But unless tbe container specifies on SPF (sun protection factor) os o number, there probably isn t enough sunscreen to do much good. In this interview, Ms. Tayog shares other cosmetics savvy that con make you o wiser shopper. 

---