Sun Damage: How Does It Occur?

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Thursday, February 28th, 2008 Subscribe To Our Feed

The sun damages our skin, this is not news but how does this occur. It is common knowledge that sun exposure causes premature aging of the skin as well as skin cancer but there is still some confusion as to with UV rays are harmful. The misconception that tanning salons are safe and do not cause damage is still widely believed but this is not the case. The other source of confusion is that we need sunlight to survive, this is true however you only need approximately 15 minutes of sunlight per day to get the vitamin production that this provides.

There are three basis categories of UV radiation. UVC radiation is a category that is currently not a concern because it is mostly absorbed by the ozone layer of the atmosphere. This may change in the future with the ozone being depleted by pollution year after year however that is another topic completely.

The second category is UVB radiation which is probably the one that most individuals have heard about, at least the damage that it inflicts. UVB affects the epidermis (outer layer of skin) and is responsible for sun burns. It is most intense in the summer months and between the hours of 10:00 am and 2:00 pm. The other important distinction is UVB rays can not penetrate glass. Have you ever seen someone who drives a lot in the summer with their window down and one arm hanging out?

The third category is UVA radiation. Until recently UVA rays were over looked but are considered to be the most dangerous because of their penetrating capabilities. UVA rays effect the deep layers of the skin and ultimately more efficient at causing damage. It should also be noted that it is not filtered by glass, and is constant throughout the day. Unlike UVB rays, UVA rays are just as intense throughout the year and there is no reprieve in the winter months.
Although the process is not fully understood, UVA and UVB radiation are responsible for extensive skin damage including wrinkles, lowered immunity against infection, aging skin disorders, and cancer. Some of the agreed upon mechanisms for UV skin damage are collagen breakdown, the formation of free radicals, and inhibiting the immune system.
Collagen and elastin are found in a deep layer of your skin called the dermis and are responsible for the skins structure and elasticity. It has been shown that the UV rays cause the accelerated breakdown of collagen and an excess accumulation of elastin. When elastin accumulates, enzymes which are responsible for remodeling sun damaged skin by manufacturing and reforming collagen are produced in large quantities. The problem however is the formation of new collagen in disorganized and solar scars are produced. When this process is repeated again and again wrinkles are formed.

Free radicals which are created by UV radiation are unstable oxygen molecules (they have only 1 electron instead of two). To bring themselves back to balance the free radicals will steal an electron from another molecule and the process cascades. This process damages cell function and can alter genetic material. The disruption in cell function causes an increase in the production of the enzyme responsible for collagen breakdown which results in wrinkles. Damage to the genetic material (DNA and RNA) leads to cancer.

UV radiation affects the bodies defense system in two distinct ways. White blood cells and specialized skin cells called Langerhans cells are responsible for attacking developing cancer cells however they are both suppressed when sunlight causes competing chemicals to be released. Cell-suicide a process know as apoptosis is the last line of defense of the immune system which severely damaged cells are destroyed. UV exposure actually inhibits this process allowing genetically damaged cells to divide, possibly leading to cancer.

Understanding the extent to which sun damages the skin, it is apparent why prevention should be a priority. Avoiding the damaging rays of the sun needs to be a constant and on going part of our daily rituals to ensure we have healthy skin for years to come.

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