Description: Sun Protection Factor (SPF) is a popular marketing concept with little clinical relevance. Sun protection does not mean diligent use of sunscreen. This article belongs to DermaFiction series.
I am not Copernicus to say that sun is the centre of life. I do believe excessive sun exposure has harmful effects and tanning should not be encouraged. I do believe that certain wavelengths within solar spectrum can hasten the ageing process (at least the visible signs of it). But I DO NOT believe that sunscreen is the panacea for all your sun woes. I DO NOT believe that our good old sun (whom Hindus worship as Sun God) is the biggest killer, humanity has ever witnessed.
Finally I have said it! I am sure I am going to pay dearly for those two ‘DO NOT’s. I am sure the mercenaries of the notorious multi-billion dollar sunscreen industry will be lurking in the darkness to silence me forever. I can see one black Mercedes stopping in my driveway.
The magic figure of 100 SPF was the biggest and perhaps the most effective tactic adopted by you-know-who. The poor unsuspecting muggles assumed that 100 imply 100 percent protection. They never understood the magic equation of SPF that translates 50 SPF to 98% and 100 SPF to 99% protection. Then the almighty FDA shrunk all 100 SPF sunscreens to 50+ (1) recognising the limitations in present SPF determination (2). Do I hear footsteps outside?
Melanoma, the serial killer on the prowl is supposed to be sun’s recruit. But the evidence in favour of the use of UV weapon in melanoma’s killing spree is not consistent. Majority of melanomas occur in areas not directly exposed to sunlight. Circumstantial evidence suggests gene mutations. In any case our 100-SPF friends failed to control melanoma. The incidence of melanoma continues to rise at a rate faster than that of many common cancers.(3) Non-Melanoma cancers are more associated with UV exposure, but are generally not lethal. The footsteps are near now. They may be here any moment.
During 10 years of my clinical practice in India and Middle East as a dermatologist, I have been seeing one or two sun induced skin disorders every other day but I see just as many sunscreen induced acne and an occasional contact dermatitis from sunscreens. My research showed that SPF is directly proportional to amount of sunscreen applied at least on pigmented skin though cost may follow a geometric progression.(4) Many of us are not aware that an umbrella (5), wide brimmed hat and even clothing (6) can give you sun protection. This is often expressed in terms of Ultraviolet protection factor (UPF) and it comes at no cost and no side effects. Do I hear a knock on my front door?
My hands were trembling when I opened the front door. He just stared, his eyes flashing coldness, having a macabre look inside my soul. “We have our answer to FDA. Hope you have seen that” (7) he said. Only his lips moved. The rest of his body remained still.
“But you need the sun for Vit D…” (8) I could not finish. The silencer muffled the shot. But it found the target. He waited for few minutes till the sunscreen advertisement on the TV finished and walked back to his Mercedes.
1. Sayre RM, Dowdy JC, Lott DL, Marlowe E. Commentary on ‘UVB-SPF’: the SPF labels of sunscreen products convey more than just UVB protection. Photodermatol Photoimmunol Photomed. 2008 Aug;24(4):218-220.
2. Miura Y, Takiguchi Y, Shirao M, Takata S, Yanagida T, Fukui H, et al. Algorithm for in vitro Sun Protection Factor based on transmission spectrum measurement with concomitant evaluation of photostability. Photochem. Photobiol. 2008 Dec;84(6):1569-1575.
3. Aceituno-Madera P, Buendía-Eisman A, Arias-Santiago S, Serrano-Ortega S. Changes in the incidence of skin cancer between 1978 and 2002. Actas Dermosifiliogr. 2010 Jan;101(1):39-46.
4. Sandra A, Eapen BR, Shenoi SD. Effect of thickness of sunscreen on SPF. British Journal of Dermatology (Suppl). 2000;143(57):24.
5. Utrillas MP, Martínez-Lozano JA, Nuñez M. Ultraviolet Radiation Protection by a Beach Umbrella. Photochem Photobiol [Internet]. 2010 Jan 6 [cited 2010 Feb 9];Available from: http://www.ncbi.nlm.nih.gov/pubmed/20059729
6. Gambichler T, Dissel M, Altmeyer P, Rotterdam S. Evaluation of sun awareness with an emphasis on ultraviolet protection by clothing: A survey of adults in Western Germany. J Eur Acad Dermatol Venereol [Internet]. 2009 Jul 13 [cited 2010 Feb 9];Available from: http://www.ncbi.nlm.nih.gov/pubmed/19627409
7. Russak JE, Chen T, Appa Y, Rigel DS. A comparison of sunburn protection of high-sun protection factor (SPF) sunscreens: SPF 85 sunscreen is significantly more protective than SPF 50. J. Am. Acad. Dermatol. 2010 Feb;62(2):348-349.
8. Osterwalder U, Herzog B. Sun protection factors: world wide confusion. Br. J. Dermatol. 2009 Nov;161 Suppl 3:13-24.
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“If this is the case, then this pathway and its protective capacity should be taken into consideration in the design and use of broad-spectrum sunscreens.”