Sunscreens

The sun enables the life on earth. However, while enjoying its warmth, we must protect ourselves from the excessive exposure to its radiation. On this page, you will find the key points of

• why is it important to protect ourselves from the sun
• who needs protection and when
• how to properly protect yourself
• what are sunscreens
• how should we use them
• what are the benefits of using them
• what are the possible disadvantages of using them.

Why should we protect ourselves from the sun?

Exposure to ultraviolet (UV) radiation is one of the causes of skin cancer. It is also a factor that we can affect by changing our behaviour. Other significant risk factors for skin cancer include genetic factors that affect, for example, the skin colour and its ability to tan, number of moles, the repair of damaged DNA and the control of cell growth. However, these are factors that are out of our control. In Finland, 40% of the new cancer diagnoses are skin cancers, so the matter is not insignificant.

Another common skin damage caused by the sun is premature aging and wrinkling of the skin. Uncommon damages include different kinds of rashes and allergic reactions to the sunlight. Of course, exposure to sunlight has also benefits, such as the creation of vitamin D, soothing of certain rashes, decreasing of blood pressure due to release of nitric oxide from skin and the feeling of well-being that, just like the suntan, appears only after the damage has already been done.

Who needs protection and when?

The need for protection depends on the amount of expected exposure to sunlight and individual risk factors.

The universal UV Index (UVI) indicates the intensity of the UV radiation from the sun. The worldwide UVI forecast is available, for example, on the website of the Finnish Meteorological Institute. It is generally recommended to start protecting yourself when the UVI level is at least 3. Of course, the need for protection also depends on the overall time of exposure to the sunlight. However, it is important to understand that the UV radiation damages the skin even in smaller exposures and even before the skin starts reddening.

Individual risk factors include, for example, age, skin colour and its ability to tan, skin that burns easily and skin cancer risk factors. Children’s skin cells are more prone to skin damages caused by the sun. The younger the children are exposed to the sun, the more their skin cells are affected by the cumulative sun damage. Therefore, it is recommended to keep the young children away from the sun and make sure that the children who are exposed to the sun are properly protected. Cancer is developed when a cell acquires enough gene mutations over the years.  Red hair, skin that burns easily and a family history of skin cancer, including in old age, could indicate genetic risk factors.

The level of the needed protection depends on the risk factors presented above. People with dark skin tone can manage even in the equatorial zone without burning their skin, whereas people with untanned light skin may get sunburn in twenty minutes, even in the Finnish midsummer sun. 

The people who need special protection from the sun include, for example, those who suffer from severe photosensitivity (e.g. photoallergic dermatitis) or have a genetic disorder that causes skin cancer already at early age (e.g. xeroderma pigmentosum). Additionally, other groups who need special protection include patients with organ transplants and other patients receiving immunosuppressive therapy since their long-term medication increases their risk of developing aggressive skin cancers. 

How to properly protect yourself from the sun?

The best method to protect yourself is to check the time and use common sense. So, especially on a holiday in the south, it is recommended to avoid the strongest sun radiation from 11 a.m. to 3 p.m. The locals neither expose themselves to the hottest part of the day, but rather take a siesta indoors. Another method is to cover up the areas exposed to the UV radiation. Sunglasses, a hat with a wide brim and a shirt already help a lot. The third protection method is the use of sunscreen in the areas that cannot be covered by clothing. The aim is to avoid the skin to turn red and sore at any point. 

What are sunscreens?

Sunscreens are cosmetic products that are applied on the skin to help protect the skin from the sun’s UV radiation and the damages caused by it. In addition to an ointment base, sunscreens contain substances intended to protect the skin against the UV radiation (filters) that are tested and found safe to use. These substances are listed in the Annex VI of the EU Regulation (EC) No 1223/2009 on Cosmetic Products. 

These UV filters are now widely used in face products, such as in moisturising, make-up and other products to prevent the skin from wrinkling. However, the protection these products provide is usually not sufficient in a strong UV radiation exposure.

UV filters

UV filters can be classified according to their solubility (soluble, insoluble) or wavelength of the radiation they attenuate (UVB, UVA and broad-spectrum filters) and according to their chemical composition (organic and inorganic). All these filters protect the skin against the UV radiation by absorbing the energy of the sun and turning it into heat. The degree of reflection of the inorganic titanium oxide (TiO2) and zinc oxide (ZnO) nanoparticles is rather low. Products that contain larger particles are used less since they cause the skin to appear white. Therefore, using the term ‘physical UV filter’ of these filters is no longer recommended. There are currently 25 different types of organic UV filters allowed in the EU. Out of these, however, only a dozen or so from the beginning of the list are widely used. Here is a table of the frequency of use (over 10%) of the UV filters contained in 150 sun-care products in the cosmetics database of the Cosmetics Allergy Portal (table updated in January 2020). 

Antioxidants acquired from a balanced diet or dietary supplements can provide some extra protection from the sun.

Ointment bases

Sunscreens are available in different kinds of options: from thin gels and lotions to thick creams, oils, sticks, powders, shake mists, sprays and foams. The consumer can choose from these according to their preference and need. Many of the products are waterproof. Following the recommendations of today, a single product usually includes several substances that protect the skin, resulting in more efficient protection against a broader spectrum of UV rays (both UVB and UVA) and a longer period of protection. 

There are dedicated sunscreens for children which usually, as a preventive measure, do not contain organic or inorganic UV filters that can penetrate the skin. Compared with the sunscreens for adults, a larger number of children’s sunscreens are waterproof. Children can occasionally use the sunscreens for adults as well.

Sun protection factors

The level of sun protection provided by sunscreen is estimated by using a commonly agreed international method (International Sun Protection Factor Test Method). The test measures the lowest dose of UV radiation that produces the first perceptible erythema with and without sunscreen product applied on the skin (Minimal Erythema Dose, MED). An artificial light resembling the sunlight spectrum is used as a source of UV radiation, and 2 mg/cm2 of sunscreen is applied on the skin.

Today, the sun protection factor (SPF) of sun-care products is indicated according to the EU Commission Recommendation 2006/647. This table presents the four categories of SPF with numbers and descriptions:

The UVA protection factor is measured by the Persistent Pigment Darkening (PPD) method and by defining the so-called critical wavelength. However, this information is rarely included in the sunscreen labelling. In Europe, it is recommended that the products’ UVA protection factor should be at least 1/3 of the labelled sun protection factor. In the US, only products with a critical wavelength of at least 370 nm can claim to provide broad-spectrum protection. 

How to apply sunscreen?

Studies indicate that consumers apply less sunscreen than the test subjects of the SPF measuring test (2 mg/cm2). Usually people only apply 0.4 - 1 mg/cm2 of sunscreen and they do not apply it evenly. Therefore, the protection factor is often reduced by one third of that indicated on the label. The problem can be solved by using only products that provide high protection or by re-applying the product 20–30 minutes after the first application. 

All authorities and experts agree that applying sunscreen once is not enough to provide sufficient protection for the whole day. In strong UV exposure, it is recommended to re-apply sunscreen every 1–2 hours.

The benefits of using sunscreen

The use of sunscreen alone does not necessarily reduce significantly the risk for skin cancer or photoaging of the skin. In addition, it is recommended to use common sense when it comes to spending time in the sun and also to protect the skin with clothing. However, the scientific evidence for the benefits of sunscreen is so strong that the US authority FDA, which is known to be strict, allows the sunscreen labels to include a claim for anti-cancer and anti-aging effect, provided that the product offers broad-spectrum protection and has a SPF of 15 at least. If one of these conditions is not met, the label must include a warning that states that the product offers protection only against sunburn but not against skin cancer or early skin aging.

There is also strong scientific evidence that broad-spectrum sunscreens prevent some of the skin diseases caused by the sunlight, such as photoallergic dermatitis and discoid lupus erythematosus (DLE).

Possible disadvantages of using sunscreen

In a comparative blinded study conducted in Australia (both light protection cream with filter and without were applied for 7 months), as much as 18.9% of the test subjects experienced side effects from sunscreen. In later studies, most of these side effects were defined as skin irritation symptoms. Test subjects who used pure ointment base without filters experienced an equal amount of side effects than those who used sunscreen with filters. The conclusion was that the waterproof ointment base causes more irritation symptoms and oozing bumps than a regular skin cream. An unexpectedly large proportion of the test subjects whose skin had irritation symptoms suffered from atopy. These people are apparently more susceptible to skin irritation symptoms caused by creams, as well as those who have rosacea (so-called couperose skin).

Allergic reactions are caused both by the substances of the ointment base, such as perfumes and preservatives, and the filters. No allergic reactions caused by inorganic filters have been reported. The most common filter causing allergic reactions has long been oxybenzone (INCI: Benzophenone-3), which has reported to cause immediate and delayed reactions both when exposed to light and without exposure to light. Another side effect can be eye irritation. Oxybenzone is no longer widely used in Europe: only 4% of the sunscreen products listed on the Cosmetics Allergy Portal contain oxybenzone. The second substance that most commonly causes allergic reactions in Europe is octocrylene, which is very widely used. In almost all cases, the person has first been sensitised to ketoprofen contained in anti-inflammatory gels, which can cause a cross reaction with octocrylene. Cases like this have not been reported in Finland. However, if you know that ketoprofen may cause you an allergic reaction, you should avoid products that contain octocrylene.

If a sunscreen product causes you allergic reactions repeatedly, you should consult a dermatologist or seek medical help in a dermatology outpatient clinic to find out what is causing the reaction. Any substance in the product could cause the reaction, and it can be examined by various suitable tests. Often, however, the reaction is only irritant, and in that case the allergy tests will remain negative. Irritant reaction usually presents on a skin which is already irritated, for example, atopic skin, or when using waterproof products. As a precaution, the safest option is to choose unscented products that do not contain oxybenzone. 

It is important to ensure a sufficient intake of vitamin D. Avoiding sunlight and using efficient UV protection reduces the skin’s ability to produce vitamin D. However, applying an insufficient amount of sunscreen, as many people do, seems to have only a minor effect. However, with a regular use of sunscreen, it is recommended to take vitamin D supplement all year round.

Conclusion

Everyone should protect themselves from excessive exposure to sun. However, what people consider ‘excessive’ can vary a lot. The individual and circumstantial factors presented above, appropriate clothing and the use of sunscreen form the basis for enjoying the sun safely.

Tapio Rantanen
dermatologist

Literature:

• Rantanen T, Suhonen R: Ihon aurinkosuojaus. Recallmed 2011, ISBN 978-951-847-086-4.
• Osterwalder U, Sohn M, Herzog B. Global state of sunscreens. Photodermatol Photoimmunol Photomed 2014; 30: 62–80.
• Iannacone MR, Hughes MC, Green AC. Effect of sunscreen on skin cancer and photoaging. Photodermatol Photoimmunol Photomed 2014; 30: 55-61.
• FDA sheds light on sunscreens. http://www.fda.gov/ForConsumers/ConsumerUpdates/ucm258416.htm
• Foley P, Nixon R, Marks R, Frowen K, Thompson S. The frequency of reactions to sunscreens: results of a longitudinal population-based study on the regular use of sunscreens in Australia. Br J Dermatol 1993; 128: 512-518.
• Kannan S, Lim HW. Vitamin D and photoprotection. Photodermatol Photoimmunol Photomed 2014; 30: 137-145.

Katso myös nämä sivut

• Sunscreens
• Fragrance allergy
• Probiotics, prebiotics and postbiotics in cosmetic products
• Work-related rash in beauticians and hairdressers
• Effects claimed for cosmetic products must be proved
• Hair dyes and paraphenylenediamine allergy
• EU Regulation on Cosmetic Products sets the regulatory framework for cosmetic products
• Safety of cosmetic products
• Henna tattoos
• Allergic contact dermatitis
• Rosin allergy
• Compositae allergy
• Testing of cosmetic product when suspecting allergy
• INCI names
• Frequently asked questions