SUN PROTECTION

OTC TREATMENTS FOR SUN RADIATION PROBLEMS-1

The scotching summer is ahead.In tropical countries like Middle East the summer would roast the sands continously for eight months.In other parts of the world like Europe,Eastern Asia,Central Australia,and the Americas there are frequent attacks of heat waves with the raises in mercurily level as high as 45 Degree Celcius.
Our skin is more vulnerable to the attacks of heat waves especially by the Ultra Violet region of the EMR radiating from the SUN.Generally over exposure to the scotching sunlight will damage our skin
SUNTAN  is a skin response to injury by sunlight.Only UV over exposure of the skin would produce SUNTAN and SUNBURN

THE ULTRA VIOLET SPECTRUM:-

UV-B in mild exposure by evening sunlight is responsible for the preparation of Vitamin-D3 by our body from skin cholesterol
UV-B radiation is erythrogenic and long time exposure to it at peak hours like 10 a.m to 2 p.m it can cause severe erythema and skin cancers.

The sunburn is more likely to occur in high altitudes as UV-B intensity increases by every 4 % with an increased altitude height by every 250 meters. Our solar radiation contains electrical (vertical) and as well as corrospondig magnetic (horizontal) oscillating waves.Hence this is generally known as Electro-Magnetic Radiations or simply by the term EMR.
This EMR contains three portions as Ultra-viotet,Visible and Infra-red regions.Out of these three regions the Ultra-Violet or the UV region is having the heat waves with more frequent and congestive waves with shortest lenghths with the highest skin penetrating power.
The UV spectrum ranges from 200 to 400 nanometers(nm).A nanometer is one thousandth of a millimeter.Imagine the shortest lenghth of one UV wave to another.Therefore the waves are highly frequent with high penetrating power and the most dangerous.
Further the UV radiation is devided into A,B,and C. and each differ from the other by the wavelengths with corrosponding frequencies as follows:-
UV-A :-The smallest sizes of photon radiation with shortest wavelenghths ranges from 320-400 nm.UVA is having more penetrating power and can pass the ozone layer to reach the earth 10 to 100 times more than UV-B.As these are very small photons hence they are less likely causes erythema but these UV-A deeply penetrating into the dermis and make the skin more vulnarable to the effect of UV-B which is carcinogenic.Also UV-A can produce photoaging and photodermatoses on prolonged exposure.
Becareful when you go for a walking when the season is cloudy and pleasant,and on a fullmoon out walk as these seasons are the one with maximum UV-A radiations.
Further UV-A can be divided into two as 1,and 2.UV-A-1 is less likely erythrogenic and melanogenic than UV-A-2 and the UV-A-2 is more likely to UV-B.
UV-A is often tanning boths and is often entertained in the psoralen plus UV-A(PUVA) treatment of psoriasis.
UV-B they are radiations of little bit bigger photonic particles than UV-A particles with the wave lengths of 290nm to 320nm.As these are bigger particles and having less penerating power than the UV-A particles but still they can pass the ozone layer and reaches the earth,and produces more serious effects to the skin like skin erythemas,and skin cancers.
These radiations causes sunburn and suntan more effectively.A proper exposure to this radiation during sunbath with a fixed and calculated time by your skin doctor,you can get a good protective suntan at your skin.
SUNTAN is natural way of tanning or blackening your skin by calculative exposure to the sulight to protect your skin from further damages by the sun.UV-B radiation is good skin tanner because it is melonogenic.But a doctor should advice.Also a small exposure to this radiati
UV-C:-It is bigger particles than the other two radiation the least penetrating power because they have long wavelength with less frequencies and hence most of them are retained by the ozone layer from not reacing the earth.

OTHER SKIN REACTIONS TO SUNLIGHT

1.Actinic keratosis it is a precancerous condition may happen after long time sun exposure.It is typically araising at the middle or later age,with the manifestations of sharp demarcated,roughened hardened growth,which may be fltened or raise leads to squamous cell carcinoma.
2.Skin cancers
A.Squamous cell carcinoma Leasions apperaed mostly as thickened rough particles which can bleed.Among the skin cancers it accounts for 15%
B.Basel cell carcinoma It appears as pearly transluscent bumps and originates in the basal cell.It accounts for 80% of the skin cancers.
C.Malignant melanoma originates from the melanocytes and is the most dangerous form of skin cancers.It is charectorised by the changes in the appearances of moles such as colour fading,dissappearing,shape and borders of the mole becomes irregular,asymmetrical,and diameter over 6 m.m.
3.Drugs Induced Skinreactions
A.Photo-Allergic Reactions occur when light makes a drug into an antigen or a photoallergen (Hapten) if the drug is repeatedly used as skin creams.For example some creams or ointments if repeatedly uses may suddenly produce skin rashes as they become allergents due to light.
B.Phototoxic reactions occurs when light transfer a drug into a toxic form,which result into a tissue damage.
C.Implicated Drugs Many drugs are implicated in causing photo allergy or photo toxic reactions.(e.g)1.thiazides;2.tetracyclines;3.Phenothiazines;4.Sulphonamides;and sunscreens.Some drugs are producing both photo toxic and photo allergic reactions.
4.Photodermatoses They are photo reactions caused by light of specific wavelenghths.(e.g)1.Polymorphous light erruptions;2.Lupus erythematous;and solar urticaria.
5.Photoaging It is the aged appearence of skin by sun exposure and not by real aging.Dry,scaly,yellow skin with deep wrinkles,thin and more fragile.
SUNSCREEN AGENTS
People can protect their skin from violent UV radiations by avoiding exposure,by wearing protective clothings and by applying sunscreen agents.
The sunscreens should be applied evenly throughout all the exposed parts of our skin,30 minutes to 2 hrs (for PABA and PABA esters),before sun exposure to allow proper penetration,and binding to the skin.
Persipiration,swimming,bathing,clothing,sand baths,towel bath may remove the sunscreen and needed to be reapplied.
Hence we must by the products after seeing the labels for the how for the products substand inspite of persipiration and swimming.
If a product is labelled as water proof that means it can adhere on the skin upto a maximum period of 80 minutes swimming
If a product is labelled as water resistant means it can withstand with our skin upto a maximum period of 40 minutes swimming.
Sunscreens should be noted in the label for their Sun Protection Factor (SPF).Baby oils,mineral oil,olive oil,and cocoa butter are not sunscreens but can be used to produce a Tan.
SPF of 30 is enough to give 97% protection from the UV radiation.The American FDA is recommending the upper limitation of SPF is 30 only any benifits getting by increasing this limit is interestingly negligible.An SPF of 15% is the upper limitation set by Skin Cancer Foundation.Hence products with SPF mor than 30 as SPF 50 ,SPF 100 etc.etc on the labels are merely for business attractions and of no use.
SPF can be calculated by Minimal Erythema Dose (MED) of the protected skin devided by that of the unprotected skin
MED is defined as the amount of sun radiation needed to produce minimal skin redness.
For example a man who gets minimal skin redness by the exposure of his skin 20minutes to the sun and want to stay in the sun for 120 minutes can use a sunscreen with the SPF of 6 as (120/20=6).When he use the sun screen of SPF-6 should its substantivity so that it must not be femoved by swimming or clothing.
An SPF of 15 can give 93% protection from the UV-B radiation.
Some people may get allergic reactions to some sunscreen cream beware of that.

TYPES OF SUNSCREENS

Physical sun blocks are opaque preparations that can block from UV to visible portions (290 nm to 700 nm) of the sunlight.These products often contains concenterated Titanium Di Oxide,and Zinc Oxide.These products are not attractive for greater area use but can be used in smaller areas like upper nose.Newer products with diluted titanium dioxides are available and are more cosmetic and attractive.Red Petrolatum covers a spectrum of 290 nm to 365 nm.
Chemical sun screens acts by absorbing a specific portion of the UV radiation inorder to prevent to reach the skin.These are of 5 groups as followsl:-
1.PARA AMINO BENZOIC ACID (PABA) and its esters primarily absorbs UV-B radiations (e,g) p-amino benzoic acid,glyceryl PABA,padimate-O.
Cinnamates primarily absorb UV-B rays.(e.g) cinoxate,octyl methoxycinnate.
Salicylate primarily absorb UV-B rays.(e.g) ethyl hexyl salicylate and homosalate.
Benzophenones absorb UV-B and a portion of UV-A rays.(e.g) oxybenzone,dioxybenzone.Because of their extensive coverage these can be used for photosensitivity reactions.
Miscellaneous the newer product butylmethoxydibenzoylmethane prvides full coverage UV-A and UV-B .This product with the combination of oxybenzone,and octyl methoxycinnamate offers the greatest protection in both UV-A and UV-B
Special agents of interests
Dihydroxyacetone (DHA) it offer an artificial suntan by reacting with keratin in the stratum corneum
It is not offering protection from UV rays and it is not producing natural looking tan.It's can withstand for a limited period and would peel off automatically.Also it will discolour hair and clothing.
Beta carotene a vitamin-A precursor can produce discolouration when taken orally.It is protective against some forms of abnormal photosensitivity like erythropoietic protoporphyria.But it is not protective against sunburn in normal individuals.
Tyrosine As tyrosine is a precursor in the synthesis of tan producing pigment melanin it is also used as an tanning agent but it is not a proved agent.