WHAT IS UV RADIATION?
Everyone is exposed to UV radiation from the sun and an increasing number of people are exposed to artificial sources used in industry, commerce and recreation. The skin’s built in cellular protection systems gradually decline with age and the endogenous production of free radicals increase due to metabolic changes. Our environment also plays a role in the formation of superoxide radicals. UV radiation and pollutants all promote the formation of these radicals which are one major causes of skin aging and skin pigmentation disorders.
Therefore of all the skincare formulations applied to the skin, sun protection is one of the most important in order to protect it from further damage and the appearance of dark spots.
All sun protection is not created equal, as various types of compounds protect against different bands of radiation. We need to understand what the UV spectrum is and how it affects the skin to make more informed and better choices.
Emissions from the sun include visible light, heat and Ultraviolet (UV) radiation. Whereas UVC rays (wavelengths of 100-280 nm) are absorbed by the atmospheric ozone, most radiation in the UVA range (315-400 nm) and about 10 % of the UVB rays (280-315 nm) reach the Earth’s surface. Both UVA and UVB are of major importance to human health.
Small amounts of UV are essential for the production of vitamin D in people, yet over exposure may result in acute and chronic health effects on the skin, eye and immune system.
UVB radiation penetrates the epidermis and is responsible for the most epidermal damage through its ability to create erythema and sunburn. It has been labelled the tanning ray because it stimulates the melanocyte to trigger melanogenesis. UVB radiation also stimulates the cells to produce a thicker epidermis. These reactions are the body’s defence against further UV damage. High doses of UVB increases your likelihood of developing skin cancer. The exact mechanism of how UVB initiates or promotes skin cancer is not yet known. In people suffering from Xeroderma pigmentosum, a rare pigmentation disease, the ability to repair DNA damage caused by exposure to UV radiation is impaired. The much-increased rates of skin cancer in these patients suggest that direct UV damage of DNA may be the mechanism that links exposure to the development of cancer.
UVA radiation activates melanin pigment already present in the upper skin cells. It creates a tan that appears quickly but is also lost quickly. Furthermore, UVA penetrates into the deeper skin layers, and have been linked to the damage of the collagen and elastin support fibres of the dermis due to an increase in the matrix metalloproteinases (MMO’s) enzyme, collagenase contributing to dermal matrix and skin aging. Recent studies strongly suggest that UVA radiation may enhance the development of skin cancers. The mechanisms of this UVA damage are not fully understood, but a popular hypothesis assumes that UVA increases oxidative stress in the cell.
UNDERSTANDING UV PROTECTION DOSAGE
Active ingredients in sunscreens come in two forms, mineral and chemical filters. Each uses a different mechanism for protecting skin and maintaining stability in sunlight.
The most common sunscreens on the market contain chemical filters. These products typically include a combination of two to six of the following active ingredients: Oxybenzone, (Benzophenone), Avobenzone (Butyl Methoxydibenzolmethane), Octisalate (Ethylhexyl Salicylate), Octocrylene, Homosalate and Octinoxate (Ethylhexyl Methoxycinnamate).
Studies have shown that mineral sunscreens containing zinc oxide and/or titanium dioxide to be less harmful and toxic for the body than chemical filtres. However only a handful of products on the market combine mineral filtres with chemical filters.
Sunscreens are marketed by SPF, a value that represents the degree of UVB protection they offer, but not their protection from UVA rays. Unfortunately these days, a race is on among sunscreen makers to create the highest SPF that R&D can buy, it is a marketing battle fought on the ground of SPF rating that is least understood by consumers.
One of the greatest myths and misunderstandings surrounding SPF protection is that SPF is not an amount of protection per se. Rather, it indicates how long it will take for UVB rays to redden skin when using a sunscreen, compared to how long skin would take to redden without the product. Despite long-awaited changes, many sunscreens continue to carry high SPF ratings that some experts consider misleading and potentially dangerous, according to a survey of 1,400 sunscreen products by to the Environmental Working Group, a consumer watchdog group.
Many consumers assume that SPF 30 is twice as effective as SPF 15, but in fact the difference between the two is actually negligible. In terms of percentages: SPF 15 filters out 93 percent of all incoming UVB rays. SPF 30 keeps out 97 percent and SPF 50 keeps out 98 percent.
The Skin Cancer Foundation maintains that a broad spectrum (UVA/UVB) sunscreen with an SPF of 15 or higher is necessary for adequate protection on a normal daily basis. Although SPF 50 provides only 5 % more protection against UV radiation than SPF 15, on the downside SPF 50 contains much higher concentrations of chemical and potential endocrine disrupting and irritating filters. Laboratory studies indicate that some chemical UV filters may mimic hormones, and physicians report sunscreen-related skin allergies, which raises important questions about unintended human health consequences from frequent sunscreen application. Treated skin such as with chemical peelings as it is more permeable and potentially sensitive and reactive hence it is preferable to privilege the use of mineral filtres on treated skin.
No sunscreen, regardless of strength, remains effective longer than two hours without reapplication. High SPFs create a false sense of security, encouraging individuals to over expose their skin to the sun. The re application of sun protection rather than resetting the exposure time back to zero instead acts as a booster to the initial application. For example two applications of sunscreen at the 60 and 120 minute adds only around 45 minutes more protection against sunburn or 100% MED (minimal erythema dose). MED is a universal scale and threshold value used to determine each individual‘s propensity to sunburn when exposed to sun (UV intensity) or an artificial light source that may produce sunburn. UV damage can take place without skin-reddening doses of UVB radiation, and even the best sunscreens should be considered just one vital part of a comprehensive treatment regimen to protect your skin.
PREVENTION IS BETTER THAN CURE
Skin Cancer in its various form is the most common type of cancer worldwide and overall rates are increasing, mainly due to over-exposure to radiation from Sunlight. There are two main types of skin cancer melanoma and non-melanoma, the latter being more common. Melanomma are nearly always pigmented and usually develop from pigmented skin lesions.
The incidence of non-melanoma skin cancer is increasing with an estimated 1 million new cases each year in the USA alone. Survival rates for non-melanoma skin cancer are over 99% if caught early, hence the importance of surveillance and prevention treatments with a dermatologist.
If you have a mole, freckle or dark spots that you are concerned about, go and see a medical expert. It may well not be a melanoma; however, if it is a melanoma, it is crucial that it is recognized and treated early.
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