We all know suntanning can cause skin ageing and skin cancer. Although it is important to avoid excessive UV radiation, sunlight also has a positive effect on the body’s resilience, synthesis of vitamin D and boosts our mood by encouraging the release of endorphins. Balance your time in the sun and use protection.
- About 5% of the UV radiation reaching the earth consists of UVB rays with the remaining 95% being UVA rays
Ultraviolet radiation that reaches us from the sun is divided by wavelength into UVA, UVB and UVC radiation. The ozone layer protects us from almost all of the UVC radiation. UVB is also mostly absorbed by the ozone layer – although a small percentage does reach the earth. Long-wave UVA radiation is not absorbed by the ozone layer. UVB radiation intensity does not depend on the season or time of day. It also is not blocked by window glass. UVB ray impact is most intense at midday and closer to the equator where the path through the ozone layer is the shortest. Incidentally, one should note the importance of maintaining the ozone layer.
- UVB causes sunburn and DNA damage
When we talk about sun protection, we think first about UVB protection. UVB radiation causes direct DNA damage to cells, triggering inflammation and weakening immune system reaction.The main task of skin as our largest organ exists to protect us. In the case of excessive UV, a disproportionate amount of energy is spent on protection and fighting the damage. Our skin produces melanin to fight UV radiation. Melanin’s dark colour absorbs UVB radiation. Melanin also acts as an antioxidant. Antioxidants neutralise the free radicals produced by UV radiation. The human body also has various other defence mechanisms: enzymes continuously repair DNA damage, and epidermis may become thicker over time to provide better protection.
Again, UVB radiation levels depend on the time of day and seasons, and excessive exposure may over-stress the skin’s protective functions, increasing risks of mutation and skin cancer considerably.
- UVA reaches the dermis, damaging collagen and elastin and gradually causing wrinkles
Secondly, we must also look at UVA. Long-wave UVA radiation reaches deeper into the dermis. Its DNA damage is not as direct as in the case of UVB. However, the absorption of UVA in the dermis produces reactive compounds that damage collagen and elastin, the proteins that give skin its firmness. Several studies have also confirmed a strong connection between UVA and highly dangerous melanoma.
Damage from free radicals is not perceived immediately. Sunbeds – which use UVA – taken in your 20’s will be evident in your 30’s in the form of sagging skin. Chemical self-tanning lotions intensify harmful free radicals; we recommend avoiding these completely.
- SPF does not determine when and how long you can stay in sunlight. You do!
SPF stands for “Sun Protection Factor”. It is a system that indicates how much protection your skin gets from UVB radiation. Note that SPF is not related at all to UVA radiation. There are generally two ways that SPF lotions provide UV protection: the chemicals absorb UV radiation, or they reflect it back from skin.
The tests to calculate the SPF level of a particular product involve applying 2 mg of cream to a square centimetre of skin: in other words, about 40 g of cream per human body. In reality, hardly anybody ever uses this much lotion. In order to determine a safe period of time for sunbathing, you should consider the intensity of UVB (so the height of the sun), the amount of cream you’ve applied, and your skin type. If the bottle reads SPF15, you might think that it extends the sunbathing time without sunburn by 15 times; but in reality the given number should be divided by around three.
- Melanin and suntan as a defence reaction against UV radiation. What should you know about it?
Melanin gives skin its pigment. It is produced in cells called melanocytes, that are located between the epidermis and dermis. On a molecular level, suntanning increases the skin’s production of melanin to absorb the harmful UV radiation and neutralises free radicals, also resulting in a darkening of the skin. The immediate darkening of the skin right after exposure is due to the melanin that we already have in our skin reacting to UV radiation. Then, new melanin is formed for 2-3 days after sun exposure (called delayed tanning).
Note that our skin requires UVB exposure to produce protective extra melanin, so there is no use to prepare for sun holiday in sunbeams, since they use UVA radiation. Large doses of UVA can produce pigment spots that begin to appear in your 40’s. These are the natural ageing of the skin, and avoiding overexposure is the only way to prevent them.
- Several substances that absorb UV radiation can damage both the human body and aquatic organisms
Studies have shown that retinyl palmitate – a form of vitamin A – damages the skin by releasing free radicals after exposure to UV radiation, and therefore potentially increases the risk of cancer. We recommend avoiding products with this ingredient. Other ingredients to avoid include oxybenzone, parabens and fragrances, that can all have an adverse effect on the skin when exposed to UV radiation by releasing free radicals that cause cell damage, encouraging hormonal changes or causing allergic reactions. Both mineral radiation blockers and chemical blockers can have a negative effect on aquatic life. Chemicals can also be toxic to sea phytoplankton, crustaceans, seaweed and fish.
In the section 5 below, we provide a list of ingredients to look for, and ones to avoid.
- Organic oils can protect against UVB
Some natural oils can provide a natural SPF. Remember though that SPF is not constant in oils, and that they generally only provide protection against UVB. Raspberry seed oil, however, provides both UVB and UVA protection and it is comparable to titanium dioxide in its efficacy.