A hundred years ago suntan indicated affiliation to lower social classes. Fifty years ago it was a symbol of welfare and health. How is it now? Today still most of us dream about golden skin tone. However the awareness of damages connected with exposure to ultraviolet radiation make us have sunbathing under control and manufacturers of lotion with UV-blockers are in bloom. Nevertheless there still patients whose skin looks 20 years older than the records say and who comes to dermatologist not only because of cosmetic but because of a number of pathogenic changes including skin tumours. And this is why it is still very important to keep informing about undesired effects of long-lasting exposure to the sun or visiting solarium.
Solar light has negative impact on skin due to the UV waves from range 280-400nm. Ultraviolet radiation is divided into three ranges:
- UVA – 320-400nm, this radiation makes about 95% of total radiation which reaches surface of Earth. It is responsible for skin pigmentation and suntan. Unfortunately it is also responsible for photoaging and skin tumours.
UVA radiation is not fully blocked by the clouds or car windshields. So even inside a car or sunlit room we are exposed to it.
- UVB – makes about 5% of total radiation which reaches surface of Earth. It is responsible for sun burns and for skin pigmentation too. It has the greatest impact between 10a.m. and 3p.m. It is blocked by windshields. For many years it was believed that this radiation is the main reason for detrimental changes to skin resulting from sun exposure.
- UVC – is absorbed and dispersed by the ozone layer surrounding our planet. It is used for sterilization in laboratories.
The appearance of an ozone hole is still under discussion because the risk of UVC and UVB exposure to human beings increases (under normal conditions radiation is partially blocked by ozone).
Exposure to UVA and UVB at a time results in more severe changes than it could be deducted from simple mathematics. UVA radiation penetrates deeper and escalates harmful UVB. Skin has a several defending mechanisms protecting against UV radiation energy. One of them is presence of colour compounds such as melanin and other structures among other collagen, which role is to absorb and disperse UV as well as stabilising free radicals. Unfortunately constant exposure to UV leads to damages in DNA, changes in connective tissue and losing stability of cellular membranes. Also horny layer of skin (stratum corneum) has ability to reflect part of radiation, so it is sort of protection.
Exposure to the certain amount for UV – after 2-6 hours, results in erythema which is a symptom of sun burn, in the other words – severe skin damage by UV. Erythema appears because of both UVA and AVB radiation. They cause higher blood flow and its intensification is opposite proportional to the amount of melanin in skin. The change of a skin colour into brown depends on genetic determinants such as race and melanin content in skin (within white race we distinguish a few photo-types of skin, out of which one never suntan but always sunburns, and another always suntans before getting erythema). Intensity of suntan depends on a content of melanin accumulated as a response to UV. This is a two-phase phenomenon. In the first phase, during exposure to solar light, photo-oxidation occurs and immediately pigment gets darker. The effect of the second phase is noticeable after approximately 72 hours. Intensification of melanin synthesis in epidermis takes place and a number of melansoms increases.
(Rhomboidal skin in a neck; chronic after-sun skin damage)
Chronic of skin is caused by long-lasting exposure to the sun and may have mild or severe course – from both fine and deep wrinkles, through flaccidity, to changes in pigmentation and vascular changes. Pale complexion is more vulnerable to severe consequences of sunlight damages. Also people working in a direct sunlight like farmers, fishermen or those spending a lot of time in solarium or excessive sunbathing in hot countries belong to the group of higher risk.
Of course wrinkles, increasing flaccidity and dryness of skin are also elements of natural, biological process of ageing and occur to people who do not sunbathe. However kind of wrinkles, widened vascular vessels (teleangiectasias), blotches, discolourations and yellowish shade of skin are characteristic to people who do sunbathe and they are intensified. Sun affects degeneration of elastic fibres, intensification of elastosis, cumulation of glycosaminglycans, decrease of collagen fibres, increase of number of fibroblasts. All these processes are main reasons for irreversible changes to epidermis such as thickness and reduced elasticity.
The difference between condition of suntanned and untanned skin is well reported in literature on an example of a teacher who worked in a classroom where one wall was windows. She always had windows on her left side. After 40 years of work there were significant macroscopic differences in elasticity and number of wrinkles.
Photoaging is not only an acceleration of natural ageing process. It intensifies damages because some cellular structures are damaged while some repairing processes are inhibited.
Wrinkles are the first results of photoaging. At the beginning they are tiny but with time they become deeper and grooves are formed. This happens because collagen destruction is intensified by UV radiation.
Lentigines (also called liver or gerontic stains) start appearing on the skin at outer parts of hands, face, arms and lower-arms. They are of various intensification with 95% of people of white race. They may not change throughout a whole life, but some of them may evolve into a malignant lentigo which is the first stadium of benign melanoma and is lethal in most cases.
Numerous clusters of concentrated melaninized cells usually located on face are freckles (or ephelides). Long exposure to sunlight make them darker and increases their number.
Rhomboidal skin of neck occur after many years of working outdoor for examples as construction workers. Skin is bleary, rough, tough and with grooves in a shape of rhombs.
In the area of eyes there may appear numerous comedos, cysts and grooves, and skin may become yellowish. These are symptoms of Favre-Racuchot syndrome which is one of the most serious skin damages caused by sunlight.
Web-like discolouration usually appear on lateral parts of neck as well as on face and upper part of a chest. The area just under chin is protected against UV and usually is free from any changes. Almost only women suffer from this symptom what is caused by hormonal factors. Similarly chloasma – discolouration on chicks – refers to women in their menopause, pregnancy or using oral contraceptives. In the last case the risk of discolouration is higher when affected by tanning.
(Rhomboidal skin of neck, mottled skin of back, flaccid skin of arms)
At elderly age there start appearing characteristic ecchymosis (solar peliosis). This symptom is connected with fragility of capillary vessels resulting from degeneration of supportive connective tissue of skin. Even minor injuries may cause disproportionate massive bloody haemorrhages.
Over-calloused, desquamating stains and ciliary cartilage on hands, face or other parts of a body exposed to sunlight are called senile callousing (solar). Apart from cosmetic defect, some of these changes are starting points for neoplasm of skin. According to statistics described in literature, 20% undergo such evolution. Thus when manicurists notices solar callousing, she should oblige a customer to visit dermatologist in order to prevent development of neoplasm. Pathologically changed skin on hands – including callous – and nails stylization doesn’t go together and may harm reputation of a nail salon (especially in case of neoplasm diagnosis). Isn’t ironic in our times that the number of diseases increases although we use more UV blockers. It happens because such UVB filters our skin doesn’t get sunburnt and our exposure to UVA is longer. So the risk is higher too. The most effective method of prevention from skin damages – apart from no tanning – is using shields both physical and chemically active. Physical shields work as a mirror which reflects and disperse UV radiation. The drawback is that the are visible on skin, for example zinc paste – one of the older sun protector). Chemical shields and transparent. They absorb both UVB and UVA radiation (for complete protection it is necessary to use a mixture of different chemical filters). The level of protection from sunlight is described as a SPF (sun protection factor) and its number is a result of dividing minimal dose of UV radiation that causes erythema of protected skin by a dose that causes erythema of unprotected skin. A lot of beauty products contain UV shields but only SPF 15 (or higher) ensures optimal protection when used regularly a few times a day by a person of II photo-type. Clothes also protect from UV. Cotton T-shirt is equal to SPF 8. Industry is developing clothes of SPF 36. In case of solar damage of skin, we should avoid further exposure. Skin should be covered with shield cream 30minutes before getting out (this is the time needed for cream to penetrate through stratum corneum), and later sun shield should be applied every 4 hours (including lips). It is not recommended to sunbathe from 10 a.m. to 2 p.m. when UV is the highest.
Tretinoin is a derivative of vitamin A and may minimize effects of photoaging and enable restoration of collagen. It is available on prescription in a form of cream or gel. Tretinoin stabilises collagen, increases its synthesis and has positive impact on damaged skin keratin. It is good for solar discolouration, lentigines and solar callousing. It leads to relief of symptoms. After cure with this medicine skin becomes soft and less rough. Wrinkles are reduced and skin looks younger. Due to irritation, skin blushing and a number of dermatological contra-indications tretinoin cannot be used during pregnancy and must be prescribed by a doctor.
(Numerous points of senile callousing)
Also alpha-hydroxy acids are significant countermeasure of skin ageing processes caused by sunlight. Their use leads to thinning of stratum corneum (horny layer) and refining minor wrinkles. The application of glycol acid and trichloroacetic acid may have positive impact on reduction of deeper wrinkles along with increase of risk of discolouration and scars (that is why these acids should be applied only by experienced professionals and acids of higher concentration should be applied by doctors).
Considering reaction of skin after exposure to sunlight, we should neglect photo-allergies (photosensitisation). Some chemical compounds contained in beauty products, herbs may have negative negative influence on relation between UV radiation and skin. UV radiation may lead to skin inflammation frequently accompanied with a rush and permanent discolourations. If a worker of solarium doesn’t ask a customer about medicines she/he uses (unfortunately it hardly ever happens in Polish solariums) and lets a customer use it for a certain way (time and type of lamps), such situation may end up with massive skin burn. Photo-sensitiziting substances are: John’s Wort herb, psoralens (to use only under doctor’s supervision; it’s completely forbidden to suntan in solarium or in the sunlight while using medicines of this group); chemical colourants; quinones, eosin, methylene blue, rose bengal sodium; medicines: barbiturates, sulphonamides, anti-inflammatory non-steroid drugs, some contraceptive medicines, tranquillizing phenotiazines, retinoid derivatives, some beauty products, UV filters (!!) such as benzophenons, cinnamic acid derivatives, oxybenzone, PABA acid, PABA esthers; fragrances such as: musk, lavender oil, cedarwood oil, vanilla oil, sandal oil, bergamot oil. Frequent discolouration on lateral parts of neck are evidence for using perfumes without UV filter.
There is also a group of diseases they may be induced or whetted by UV radiation and this doesn’t depend on outer substances. This kind of diseases is called photo-dermatosis and they are not related to allergy. For some of them future prognosis can be very serious, for example DLE (discoid lupus erythematosus) when untreated, leads to death.
No matter on our health condition, we have to be reasonable and moderate when we plan sunbathing. Intensive suntan not only makes us look older but also induces pre-malignant changes and malignant themselves. Protecting ourselves from intensive sunlight and UV radiation, we care about our health and beauty.
Dr hab. n. med. Małgorzata Sokołowska-Wojdyło
Department and Clinic of Dermatology, Venereology and Allergology of GUMed