Sun and Skin (Photoderm)

8/11/2019 Sun and Skin (Photoderm)

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Solar radiation is responsible for most of the deleterious skin conditions that are often erroneously

attributed to aging, such as:

the appearance of sun spotsthose brown spots that tend to appear on areas of skin exposed t

the sun,

the appearance and accentuation of wrinkles and sagging skin, Enlargement of blood capillaries on the face, and the development of various skin tumors.

The suns radiation ranges over a wide spectrum of wavelengths.The wavelength of ultraviolet radiation

is adjacent to that of visible violet light. Ultraviolet- B (UVB) (290-320 nm) rays are high-energy

emissions, which can cause significant damage to living tissues and cells. This is the main type of

radiation that is responsible for: sunburn, tanning, and the appearance of skin tumors following

prolonged, cumulative exposure to the sun.

The energy level of ultraviolet-A (UVA)(320-400 nm) rays is less than that of UVB rays, so they cause

less skin damage. UVA waves are divided into short UVA (320-340 nm) and long UVA (340-400nm).This long length makes the UVA wave incapable of holding many photons (a photon is a basic element

of nature. It can't be destroyed into smaller elements. It was first identified by Max Planck in 1900 as the

packets of energy). So, carrying no energy, it can't be felt (no heat sensation caused).

Until recently, UVA rays were thought to provide safe tanning, and most solariums still use lamps that

emit UVA for achieving a tan. However, even UVA rays cause skin damage. UVA rays discreetly

penetrate skin deep into the epidermis and cause cellular DNA damage. UVA also cause the production

of more free radicals. It also causes temporary pigmentation (or short term tanning) which lasts for a

couple of hours. Moreover, UVA rays penetrate deeper into the skin than do UVB rays, causing damage

to the elastin fibers located deeper in the skin, and thus hastening skin aging.

Another fact that must be kept in mind is that UVB rays do not penetrate glass, while UVA rays do.

Therefore, for example, when driving in a car with closed windows, skin damage can occur because of

the UVA radiation. Hence, in an air-conditioned car, one tends to forget that the skin is still exposed to

ultraviolet radiation. Therefore: It is not advisable to expose oneself to the suneven through a glass

window. Tanning at a solarium can damage the skin.

What is Suntanning?

When we talk of suntanning, we mean that the skin color darkens. From a medical point of view,

suntanning is, in fact, the natural mechanism by which the skin protects itself. The suns rays that reach

the epidermis cause the melanocytes, that is, special cells in the epidermis, to produce melanin, which

is the colored compound (pigment) that makes the skin darker. Melanin provides the skin with natural

protection against solar damage. However, the amount of melanin that is produced in fair-skinned

people following exposure to the sun is relatively low and does not afford them adequate


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protection,and they must take additional precautions against solar skin damage. In dark-skinned

people, the amount of melanin produced is higher and is consequently more effective . That is wh

dark-skinned people often look younger than fair-skinned people of the same agein the former, the

skin changes less with age, and wrinkles and pigmented patches appear less frequently. Nevertheless,

even dark-skinned people should avoid excessive sun exposure. Tanning does afford the skin a certain

degree of protection, but usually not sufficient to prevent skin damage.

Sunburn

Apart from tanning, ultraviolet radiation also causes redness. The medical term for this redness is

erythema, and its appearance following exposure to the sun has nothing to do with melanin production

Erythema begins soon after excessive exposure to ultraviolet lightsome four to six hours following

exposurereaching its peak around 24 hours thereafter. A mild burn (termed first-degree) is manifeste

by redness with pain and sensitivity of the skin. A deeper burn (second-degree) appears following mor

prolonged exposure to the sun and is manifested by the appearance of blisters, peeling, and severe pai

The treatment of first-degree burns is based on cooling the burnt area by rinsing with water. Soothingapplications can also be used, such as those containing aloe vera. A second-degree burn (or a relativel

severe or widespread first degree burn) requires medical attention. In second-degree burns antibacteri

preparations, which inhibit or kill bacteria and prevent infection of the burn, may be used. Silver

sulfadiazine,an effective product for treating burns, is active against bacteria and cools and soothes th

burnt area. It may be used in cases of severe sunburn.

Vitamin D and the Sun

Vitamin D is needed by the body to build and strengthen bones.Recent research studies have

suggested that an appropriate amount of vitamin D may assist in preventing certain kinds ofmalignancies and certain disorders of the immune system. Exposure to sunlight stimulates the

production of vitamin D in humans. It should be noted, however, that the amount of sunlight needed to

produce the vitamin D required by the body is minimal. Exposing a few square centimeters of skin for a

few minutes daily is sufficient. There are certain people who may lack vitamin D, however, especially

those living in northern countries, the elderly, the incapacitated, and people who intentionally avoid any

exposure to the sun for religious, medical, or any other reasons. Absolute avoidance of sun exposure is

definitely not desirable. On the other hand, worrying about an adequate supply of vitamin D is certainly

no justification for excessive sun exposure. This is especially important in people with extremely fair

complexions, those with a history of skin cancer, or those with evident sun-damaged skin. Low levels of

vitamin D can be rectified by the ingestion of tablets, along with a proper diet including foodstuffscontaining vitamin D.


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LONG-TERM EFFECTS OF SUN EXPOSURE: SKIN DAMAGE

The changes that occur as a result of exposure to the sun are not the same as those processes that

occur with natural aging of the skin are known technically as photoaging.

Effects on the Epidermis

Freckles: an uneven distribution of pigment in the skin in young people caused by prolonged

solar exposure.

Solar Lentigines:In older people, the solar exposure leads to the appearance of sun spots.

Benign tumors:solar keratosis.

Malignant tumors:malignant melanoma, basal cell carcinoma, and squamous cell carcinoma.

Effects on the Dermis

The destruction of elastin and collagen fibers Damage of the delicate blood vessels of the skin and the supporting tissues . The blood

vessels become more fragile, making them more prone to hemorrhages (bleeding) following

relatively minor injury.

The capillaries of the face may enlargea phenomenon known as telangiectasis.

What Does Sun Protection Factor Mean?

The effectiveness of a given SPF is measured in terms of the redness (erythema) that appears on the

skin following sun exposure. The concept of a minimal erythema doseis an expression of the minimaamount of radiation that causes reddening of the skin. This radiation dose varies from person to person

depending on his/her skin shade and type. For example, if it takes someone, without any sunscreen, 10

minutes of sun exposure to develop erythema, exposure to that same strength of sunlight by using a

sunscreen with an SPF of 15 will take 150 minutes (10 15) to develop erythema.

Considerations of Various Sunscreens

There are four main considerations when using a sunscreen: endurance on the skin, skin irritation,

eye irritation, and SPF.

1) Endurance on the skinAccording to the FDAs definitions: A water-resistantproduct provides skin protection even after 40 minutes of immersion in (fresh)

water.

A waterproofproduct retains its protective capabilities after 80 minutes of immersion in (fresh)

water.

A product that does not lose more than 25% of its effectiveness after a 40-minute swim is

recognized as water-resistant.


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A product that loses over 25% of its effectiveness after a 40-minute swim is not water-resistant.

2) Skin irritation

Skin sensitivity tends to be more of a problem with chemical sunscreens. In the past, para-

aminobenzoicacidwas used in most sunscreens, but in recent years the trend has been to replace it

with other sunscreens of the oxybenzoneand benzophenonegroups, which cause fewer skin

irritations. Physical sunscreens, on the other hand, generally do not cause skin reactions. In many

cases, skin sensitivity from contact with sunscreens is caused by other ingredients in the preparation,

such as the perfumes or preservatives, and not necessarily by the sunscreen itself.

3) Eye irritation

Stinging of the eyes is a common side effect experienced after applying a sunscreen. The stinging

sensation is most commonly related to irritation of the eyes from the fumes of the preparation. People

who encounter this problem should change to a different sunscreen (preferably a physical sunscreen

that contains titanium dioxide). In general, any sunscreen can cause irritation if it comes into direct

contact with the eyes, as a result of the user rubbing the eyes after applying the preparation, or because

the sunscreen is too runny. Water-resistant sunscreens tend to be less runny, and are recommended fo

the area around the eyes.

4) Sun protection factor (SPF)

While until recently, SPF of 15 was considered to be optimal, many doctors now recommend using

preparations containing an SPF of 30 or greater. For people with skin type 1 or 2 and for certain people

at high risk (such as those with an increased risk of skin tumors) a preparation with an SPF of over 30

may be necessary. The recommended SPF depends not only on peoplesskin types, but also on the

length of time they intend to be in the sun.

Note: A sunscreen is considered to afford effective protection only if it has an SPF of 15 or greater. A

sunscreen with SPF 15 blocks about 93% of UVB radiation. A sunscreen with SPF 30 blocks about 97%

of UVB radiation. In sunscreens with SPF higher than 30, the additional improvement in the protection

from ultraviolet radiation is minimal.

Sunscreens may be physical or chemical. Most sunscreen preparations contain both physical and

chemical sunscreens, and may be in the form of a cream, an ointment, an emulsion, a gel, etc.


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Physical sunscreens prevent the suns rays from reaching the skin by reflecting and dispersing them,

as a mirror reflects light rays. The major component of physical sunscreens is a substance similar to tal

called titanium dioxide (anti-UVB) or zinc dioxide (anti-UVA) and Iron oxide (visible radiation).

Chemical sunscreens absorb ultraviolet rays, thereby preventing them from penetrating the skin. The

degree of absorption depends on the particular substance used and its concentration. Substances used

as chemical sunscreens are oxybenzone, benzophenones, and paraaminobenzoic acid (PABA).

These names can be found on the packages of different sunscreen preparations.

Sun Related Skin Pathology:

There are two main types of sun-related disorders: sun inducedand sun aggravated. The sun induce

ones are the ones that start after the exposure to the sun. However, the sun aggravated diseases startaway from sun exposure and get worsened after exposure to the sun.

The sun induced disorders are diseases like Benign Summer Light Eruption or Sun Allergy, skin

ageing, Skin Cancer and Photosensitisation. These four are induced by the sun exposure. The sun

aggravated diseases are ones like Vitiligo, Acne and Rosacea (Mainly Couperosis) and other hype

pigmentation disorders.

It has been proved that UVs play an integral part in accelerating the symptoms of skin ageing, especiall

in fair skin. This is due to the fact that Phaeomelanin (the melanin in fair skins) is a strong inducer for

the production of free radicals.

Documents

Sun and Skin (Photoderm)