May 25 2007
Sunscreen? For a long time this meant nothing more than protection against sunburn, which is caused by part of the sun’s ultraviolet rays known as short-wave UVB radiation. Long-wave UVA radiation, which accounts for 90 percent of the UV light that reaches the earth, was always thought to be harmless. But now we know that it also affects the skin: among other things, it causes the skin to age prematurely, a process known as photoaging. The characteristic signs include wrinkle formation, decreased elasticity of the skin, pigment spots and lowering of the body’s immune function. Since the body gives no warning of excess UVA radiation, as it does for UVB radiation by developing sunburn, the effects accumulate unnoticed and only become apparent after years.
Sun creams have so far offered protection only against UVB radiation and thus against sunburn, but too little against UVA radiation. The EU Commission has now recognized the problem and last year issued a recommendation that sunscreen products should also provide a minimum of protection against UVA. Even without sunbathing, we are exposed to UVA radiation more often than generally assumed – even under a cloudy sky, in the half-shade and behind windows. "UV filters are increasingly being used in daily skin care and decorative cosmetics. In these applications, special emphasis should be placed on providing reliable protection against free radicals and premature skin aging. Both are caused mainly by deeply penetrating UVA rays", explains Dr. Heike Flößer-Müller, sun protection expert of BASF's Technical Support Cosmetic Solutions. "BASF has developed the highly effective and reliable UVA filter Uvinul® A Plus, to address this need."
UVA radiation causes mainly chronic damage to connective tissue. It generates free radicals, highly aggressive reactive compounds that attack everything around them. For example, they harm cell membranes and cause genetic damage – leading to disturbances of the finely tuned balance of cellular functions. The body's natural breakdown of connective tissue fibers consisting of elastin and collagen is also overstimulated by UVA radiation. The skin then loses elasticity and moisture and wrinkles form or deepen. The innovative UVA filter Uvinul® A Plus protects against these effects. It absorbs the incident radiation and converts it into harmless heat. The substance is highly light-stable, which ensures long-lasting protection. Professor Leonhard Zastrow, Head of Research for the cosmetics manufacturer Lancaster in Monaco, has tested the filter: "Uvinul® A Plus is able to efficiently intercept UVA radiation – thereby considerably reducing the formation of free radicals in the skin.
It also can be superbly combined with other cosmetic ingredients. For us as a cosmetics manufacturer, that is a major advantage." BASF's all-round UV protection concept includes not only chemical UV filters like Uvinul® A Plus, but also physical filters which reflect the sun's rays – both long-wave UVA and short-wave UVB radiation. Miniscule particles of titanium dioxide and zinc dioxide serve as mini-mirrors. They measure no more than a five thousandth of a millimeter and are therefore invisible on the skin. About 400 of these particles would have to be placed side by side to obtain the thickness of a human hair. Although they are so minute, these particles are not absorbed by healthy skin from sunscreen products. This is shown not only by BASF's own investigations but also by independent studies performed as part of the EU Nanoderm project. Even the best filters, whether chemical or physical, and highest sunscreen factors cannot prevent a small amount of UV radiation penetrating into the skin. BASF's products keep the damage at bay: highly active antioxidants such as special forms of vitamin C and E deactivate free radicals and protect the skin cells against oxidative stress. Active agents derived from chamomile and the provitamin B5 simultaneously exert antiinflammatory and conditioning effects. Vitamin A normalizes the breakdown of connective tissue fibers overstimulated by UVA radiation, cell regeneration is activated and the depth of wrinkles is reduced."With its UV filters, antioxidants and other skin soothing and normalizing agents, BASF offers a well coordinated and interacting, threefold protective system against UV radiation and its harmful effects", says Dr. Heike Flößer-Müller. "We should act responsibly where the sun is concerned – not just on vacation but also in everyday life."
The Prospects
Climate change will mean a further increase in the UV radiation reaching the earth's surface. Growing numbers of consumers are beginning to realize the importance of obtaining protection especially against UVA radiation, and of safeguarding skin against premature aging and other forms of sunlight related damage. The quest for youthfulness and beauty with radiant, wrinkle-free skin has created what is now one of the world's most lucrative markets – the anti-aging industry. An international study conducted by the marketing information company ACNielsen in June 2006 showed that the anti-aging skin care sector currently accounts for 30 percent of the total international market for skin care products. In Germany alone, almost Euro 280 million was spent on anti-aging products for face care. Increased awareness in the population, the anti-aging trend and not least the pressure from the EU recommen-dation will in the near future lead to more widespread use of UVA filters – both in sunscreens and in products for daily skin care and decorative cosmetics. Industry insiders are now talking about annual growth rates of 5 to 6 per cent in this segment.
The Info Box
UV filter substances perform many different functions
They reduce the amount of UV light penetrating into the skin by reflecting, dispersing or converting it into harmless heat. Usually, several different filters are now combined in one sunscreen product to filter out the entire spectrum of UVA and UVB radiation from sunlight. BASF is one of the world's largest producers of UV filters for the cosmetics industry and supplies many prominent sunscreen manufacturers.
Chemical UV filters: these agents absorb the radiation and convert it into harmless heat. An important feature is that the absorber molecules convert the energy without reacting with other molecules or being destroyed – that would make them ineffective. The UVA filter Uvinul® A Plus responds to the incident energy by undergoing a short-term internal rearrangement reaction known as the H-shift: the absorbed UVA radiation stimulates the molecule and one hydrogen atom migrates to a different position inside the molecule. When converted back into its original state, the energy absorbed as UV light is gradually released as heat, allowing the molecule to absorb further radiation energy. This mechanism ensures effective and long-lasting protection.
Physical UV filters: microfine particles of titanium dioxide or zinc oxide function as physical UV filters. Incident UV radiation is not only reflected, but also dispersed and absorbed by them. Since these particles are white, they can cause an undesired whitening effect on the skin at high concentrations. This is prevented by reducing the size of the pigment particles to about 200 nanometers (millionths of a millimeter) – which makes them transparent on the skin. Physical UV filters are used mainly in sunscreens with higher sun protection factors above 25. They are also suitable for the sensitive skin of children and people with allergies.