Skin protection factor

Cover skin with a sunscreen lotion with a skin protection factor (SPF) of at least 15, protecting against UV radiation (both UVA and UVB). 

Methyl silicones are also a major ingredient in personal care products. They are added to shaving lotions to provide lubrication and to give these products a non-greasy, yet silky, feeling. They help hair-styling products to spread more easily, and they increase the skin protection factor (SPF) in sunscreens. Silicones are also used in deodorants, perfumes, and nail polishes. 

Regarding the various models used to investigate the efficacy of skin-care products, the validation of a sensitive, standardized and widely accepted model proved by inter-laboratory standardization or controlled clinical studies at the workplace seems to be necessary. Clearly, studies are needed, both under experimental conditions and in the workplace, before a rational recommendation can be made whether a product is safe and effective for skin protection. In analogy to the sun protection factor, a standardized testing method should be envisioned to determine a (irritant-specific) skin protection factor for BCs and a skin regeneration factor for post-exposure skin care. 

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. 

In 1986, the antioxidant effects of thioredoxin reductase were studied by Schallreuter et al. [81]. It has been shown that thioredoxin reductase was contained in the plasma membrane surface of human keratinocytes where it provided skin protection against free radical mediated damage. Later on, the reductive activity of Trx/thioredoxin reductase system has been shown for the reduction of ascorbyl radical to ascorbate [82], the redox regulation of NFkB factor [83], and in the regulation of nitric oxide-nitric oxide synthase activities [84,85],... 

Some quality factors, especially secondary ones, depend directly on material or structural attributes of the product. These product quality factors are often arbitrary and can only be qualitatively evaluated by panels of consumers or experts. Convenience for use, product stability, and ability for human skin protection are all examples of these quality factors. Each arbitrary performance index has specific relationships with the material/structural attributes. In such cases, the desirable quality factor can be realized by directly changing the formulation without concerning any of the performance indices. An example can be that to make a laundry detergent product more convenient to use, the product form can be changed from powder to tablet. Another example is that to make a highly biodegradable product, surfactants with less branching should be used. 

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 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. 

From this, it is obvious that it is not possible to use any hydrophilic paste in any given dermatologic situation. Apart from water (exudate) absorption, which may be a significant (or desirable) component of a paste s action on the skin, occlusion is another factor of importance in situations where skin protection is required. 

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... 

Diffey B 2000 Has the sun protection factor had its day British Medical Journal 320 176-177 Fine J-D 1999 Management of acquired bullous skin diseases. New England Journal of Medicine 333 1475-1484... 

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. 

Organic acids have to overcome the protective effect posed by some food products, such as the high lipid content and topography of chicken skin, which are primary protective factors (Tamblyn and Conner, 1997). 

An SPF of 50 protects the skin against 98% of UV. A higher protection factor is not necessary. 

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 ... 

---