12/4: Sunscreen
proper hat protection
Hat should shade entire face, ears, sides of neck, and top of scalp and be made of tightly woven sun-protective material with high SPF rating
Melanotropins and Melanin Products (unproven suntan products)
alpha-Melanotropin (alpha-MSH i.e., alpha- melanocyte-stimulating hormone) is currently under investigation to see if it can affect tanning - its effectiveness is yet to be demonstrated. Melanin products have also not yet been shown to be effective
Sunburn
associated with UVR exposure as well as both drug and non-drug photosensitivity
how to reduce the incidence of premature skin aging and skin cancer
avoid excessive exposure to UVR
an SPF number tells you nothing about the effect of what?
the UVA radiation (only tells you about UVB)
UVC radiation (200-290 nm)
(also known as germicidal radiation) Little UVC from the sun reaches the earth's surface and if it hits the skin it is absorbed in the upper most skin layer - the stratum corneum (composed of dead cells)
Present assessment of sunscreen use in children
-Clinicians and researchers agree that use of an SPF-15 product starting after age 6 months and continuing throughout one's lifetime can reduce the incidence of long-term skin damage due to UVB. A product with an SPF-30+ may result in even higher reductions in sunburn, premature skin aging, skin cancer, and other skin problems. -Initially limit sun exposure to the early morning and late afternoon hours At least until a tan develops.
Transmission and reflection of UVR
-Cloud cover filters very little UVR. 70% to 90% of the UVR will penetrate -Fresh snow reflect 85% - 100% of the light and radiation that strikes it -Water reflects no more than 5% of UVR allowing the remaining 95% to penetrate and burn the swimmer -Although dry clothes reflect almost all UVR wet clothes allow the transmission of approximately 50% of UVR. Tightly woven material provides the greatest protection -Although UVB does not penetrate window glass UVA does. So even with the windows up in a car patients who are sensitive to UVA will be affected
Dosing and administration guidelines
-Face and neck: ½ tsp -Arms and shoulders: ½ tsp to each side of body -Torso: ½ tsp each to front and back -Legs and top of feet: 1 tsp to each side of body
Patient risk factors for the development of UVR-induced problems
-Fair skin that always burns and never tans -A history of one or more serious or blistering sunburns -Blonde or red hair -Blue, green, or gray eyes -A history of freckling -A previous growth on the skin or lips caused by UV exposure -The existence of a UV-induced disorder -A family history of melanoma -Current use of an immunosuppressive drug -Current use of a photosensitizing drug -Excessive lifetime exposure to UVR, including tanning beds and booths -Xeroderma pigmentosum, a rare genetic disorder
Sunscreen sprays
-Hard to get good coverage, therefore need to spray into hand and apply -Aerosols are flammable and may be toxic if inhaled
SPF (Sun Protection Factor)
-SPF is derived by dividing the MED of protected skin by the MED of unprotected skin -SPF = 15 blocks 93% of the UVB -SPF = 30 blocks 96.7% of the UVB -SPF = 40 blocks 97.5% of the UVB -NOTE: A SPF = 40 requires 25% more active agents than for a SPF = 30 product. Thus, to decrease possible systemic toxicities set maximum SPF = 30. Also, SPF is not a reliable measure of UVA protection
Mechanism of Action of Sunscreens
-Sunscreen active ingredient: An active ingredient absorbs at least 85% of the radiation in 290 - 320 nm UV range but may or may not allow transmission of radiation to the skin at wavelengths longer than 320 nm -Sunscreen opaque block: An opaque sunscreen active ingredient reflects or scatters all light in the UV and visible range from 290 to 777 nm
New Sunscreen rules (2011)
-Sunscreens cannot be labeled as sunblock because such a claim is false -Only products with an SPF of 15 or higher can claim to reduce the risk of skin cancer and early sun aging -Sunscreens must protect equally against two kinds of the sun's radiation (UVB and UVA) to be labeled as offering broad spectrum protection -Products cannot be labeled waterproof or sweatproof because such claims are false. They will be allowed to claim how long the product is water resistant -Dermatologists suggest that consumers look for products that are broad spectrum, have an SPF between 30-50 and should be reapply every 40 to 50 minutes
tanning booths
-Tanning booths presently have UVR sources that are primarily UVA radiation. The newer types have 96% UVA and less than 4% UVB radiation -If used properly, UVA can generate a tan without burning. However, there is a growing concern about the risk of skin cancer. -BMJ 2012;345: Indoor tanning is associated with a significantly increased risk of both basal and squamous cell skin cancer. The risk is higher with use in early life (<25 years). This modifiable risk factor may account for hundreds of thousands of cases of non-melanoma skin cancer each year in the United States alone and many more worldwide -Because of the lower likelihood of erythema users become complacent and forgo the use of goggles. This practice will produce eye burns and may increase the risk of cataracts. -The FDA has recently approved a new OTC for prevention of sunburn and for protection against UVB and UVA rays. It has a SPF of 15 and is called Anthelios SX. It contains ecamsule, avobenzone and octocrylene.
sunscreen introduction
-as of 2000, market was $853 million for sun care products with 65% going to sunscreen and sunblock agents -1 million people in the US diagnosed with skin cancer in 2002 with 95-99% curable with early detection and treatment. As of 2012, 2 million annually affected in US
Statement of the problem
According to the National Ambulatory Medical Care Survey (2014), there were an estimated 18.30 billion patient visits nationwide. Physicians mentioned sunscreen at approximately 12.83 million visits (0.07%). Mention of sunscreen was reported by physicians at 0.9%of patient visits associated with a diagnosis of skin disease. Dermatologists recorded the mention of sunscreen the most (86.4% of all visits associated with sunscreen). However, dermatologists reported mentioning sunscreen at only 1.6% of all dermatology visits. Given the known relationship between Sunlight UV irradiation and skin cancer, these low numbers are concerning
Sunscreen counseling by US physicians
Despite encouragement to provide patient education regarding sunscreen use and sun-protective behaviors, the rate at which physicians are mentioning sunscreen at patient visits is quite low, even for patients with a history of skin cancer. The high incidence and morbidity of skin cancer can be greatly reduced with the implementation of sun-protective behaviors, which patients should be counseled about at outpatient visits
Ultraviolet radiation (UVR) effects
Effects are cumulative and can produce serious long term problems such as premature skin aging and skin cancer
Aminobenzoic acids (PABA) (type of sunscreen)
It can effectively block UVB radiation and has significant substantivity on sweating skin although not as much when submerged in water. The primary advantage of aminobenzoic acid derivatives over aminobenzoic acid is they do not stain clothing.
Water Resistant
Product retains its SPF for at least 40 minutes
Very Water Resistant
Product retains its sun protection for at least 80 minutes
product category designations
SPF 2-11: minimal sunburn protection SPF 12-29: moderate sunburn protection SPF 30+: high sunburn protection
Sunburn and tanning history for skin type
Skin type I: always burns easily; never tans (sensitive) Skin type II: always burns easily; tans minimally (sensitive) Skin type III: burns moderately; tans gradually (normal) Skin type IV: burns minimally; always tans well (normal) Skin type V: rarely burns; tans profusely (insensitive) Skin type VI: never burns; deeply pigmented (insensitive)
Substantivity
The ability to remain effective during prolonged exercising, sweating, and swimming
sunscreen use in children
The absorptive characteristics of human skin in children younger than 6 months differ from those of adult skin. Also, metabolic and excretory systems in infants are not fully developed to handle any sunscreen absorbed through the skin. Thus, the FDA requires the statement: "children under 6 months of age: ask a doctor."
MED (Minimal Erythema Dose)
The minimum UVR dose that produces clearly marginated erythema in the irradiated site, given a single exposure
Oral pigmenting agents (unproven suntan agents)
Their active ingredients are the dyes canthaxanthin and -carotene. Both are approved by the FDA as color additives in foods. But the concentrations used in foods are 1/20th to 1/40th of that found in the oral products claiming to produce a tan. The dyes alter skin tone by coloring fat cells under the epidermal layer. The extent of tan varies from person to person. One major concern with these additives is the discoloration of the feces to brick red, which could mask GI bleeding
Benzophenones (type of sunscreen)
These agents are primarily UVB absorbers but also extends into the UVA region. Thus, many products contain these agents due to their broader spectrum and because some patients may be allergic to the aminobenzoic acid derivatives
Tan Accelerators (unproven suntan products)
These are cosmetic products that claim to stimulate a faster and deeper tan. They consist of tyrosine, an amino acid necessary to produce melanin. There is no current evidence to support that these products work
Suntan products
Those that contain a pigmenting agent and those that do not. Products that do not have a pigmenting agent are formulated with oily vehicles (e.g., mineral oil) and tend to concentrate UVR onto the skin. They provide no protection. The other type of suntan product contains the pigmenting agent dihydroxyacetone (DHA) and may or may not b e formulated with an oily vehicle. DHA has been the major ingredient in the products that claim to tan without the sun. DHA does not provide provide protection against UVR. It colors the skin a reddish brown color by binding to specific amino acids in the stratum corneum. Color fades after 5 - 7 days due to the desquamation of the stratum corneum. It colors unevenly. Particularly dry areas such as the elbows and kneecaps will absorb more DHA
UVA radiation (320 - 400 nm)
UVA radiation penetrates deeper than UVB radiation (all the way into the dermis) resulting in vascular and histological damage. It is believed to cause premature aging of the skin, can trigger herpes simplex and photosensitive reactions. UVA radiation can produce a tan without erythema and is why it is used in tanning booths
what will cause both drug and non-drug photosensitivity but UVB is most problematic
Visible, UVA (long wavelength UV) and UVB (medium wavelength UV)
Physical sunscreens (type of sunscreen)
Zinc oxide or titanium dioxide. Note: manufactures have developed a way to make titanium dioxide transparent. As such, it is being combined with other sunscreen agents to increase the spectrum of UVR protection. Problem with zinc oxide and titanium oxide is that they discolor clothing and may occlude the skin to produce miliaria (prickly heat) and folliculitis
UVB radiation (290 -320 nm)
this is the most active UVR and produces erythema which is why it is called the sunburn radiation. Therapeutically UVB aids in Vitamin D synthesis. Nonetheless UVB is thought to be primarily responsible for causing skin cancer and contributes to causing premature aging of the skin
