Misunderstanding and Truth about Sunscreen (Sunblock, Cream)
What kind of sunscreen should I apply?
Many people pay attention to ultraviolet rays only in summer. However, even in winter or rainy days, we are exposed to 60-70% of ultraviolet rays on sunny days in midsummer, and 70% of ultraviolet rays are transmitted through black tanned car glass and 40% through thin cloth. Even indoor lighting produces very small amounts of ultraviolet rays except for long, one-shaped fluorescent lights. (Of course, there is no need to apply sunscreen because of indoor lighting.)
Therefore, it is best to apply sunscreen all year round. About 90% of our skin's aging is due to ultraviolet rays. If you look at people who have been sick in the hospital room for decades due to the aftereffects of various diseases, you can see that their faces are very young without wrinkles, pigments, and no wrinkles. If you look at those who have driven trucks for a long time, your left face looks much older than your right. As such, photoaging is fatal. Even if you use sunscreen well, you can look nearly 10 years younger than your peers when you are in your 60s and 70s at no big cost.
Some people say, 'Modern people are too sensitive to ultraviolet exposure. "What do you mean by blocking all of your bones when you get UV rays?" It makes sense. 90% of vitamin D, which helps absorb calcium in the body, is made from the skin, and vitamin D can be synthesized from the skin only by squeezing ultraviolet B. Furthermore, Korea is one of the countries with the most severe vitamin D deficiency. It means that I lack sunbathing. In the 2010 National Health and Nutrition Survey, 47.3% of men and 64.5% of women were deficient in vitamin D. About 10% had little vitamin D.
So how much do you need to get in the sun to synthesize enough vitamin D? In summer, if you expose your limbs with sunscreen only on your face and expose your face for about 15 minutes a day, and in winter, with your face and hands and feet exposed for 30-40 minutes, there is no shortage of synthesizing vitamin D (1000 IU) needed per day. Sunbathing time is also very important, but in summer, the sun is too strong between 10 a.m. and 2 p.m., so it is recommended to avoid sunburn and sunbathe at this time in winter, on the contrary to winter. If exposure to sunlight is difficult, there is a way to take vitamin sanctions or supplement them through muscle injections, but if you eat them, it is more effective to take vitamin D3 made by your skin than vitamin D2, and if you want to get a hip injection, 2-3 months apart. Especially in winter.
When choosing sunscreen, the most important thing to consider is its ingredients and UV protection index. Depending on the ingredients, sunscreen can be divided into inorganic sunscreen (inorganic sunscreen) containing metal components such as zinc and titanium and organic sunscreen (organic sunscreen). The metal component of inorganic sunscreen is stable against light, so it maintains for a relatively long time, does not absorb all over the body, and causes little skin trouble, but the "white cast" that appears white when applied is a big disadvantage. Also, the applicability is lower than that of chemical sunscreen. When time passes after application, organic sunscreen feels greasy, but inorganic sunscreen sometimes feels dry on the contrary. Recently, however, the size of metal particles has been reduced, and some formulations with less white cast have been released, reducing the degree to which they appear white. Recently, most of them are sunscreen, which is a mixture of organic and inorganic ingredients, and there are many products that apply well and do not have white cast.
However, it is recommended to use inorganic sunscreen (inorganic sunscreen) for infants under the age of 2 and severely sensitive skin. In particular, children can rub and eat sunscreen, so sunscreen containing titanium dioxide (TiO2) that is less irritating to both the skin and mucous membranes is good. Infants under 6 months of age are advised not to apply sunscreen.
Many people complain of having trouble after applying sunscreen. However, contact dermatitis is rarely caused by sunscreen. Usually, products with a high UV protection index use a lot of organic solvents (there are many types of sunscreen such as PABA) to dissolve sunscreen ingredients in the product, and most of these ingredients cause allergies or membranes to irritate the skin and cause trouble. The higher the UV protection index, the higher the concentration of UV protection materials and the higher the concentration of organic solvents to dissolve them. Therefore, if you keep having troubles after applying sunscreen, it is recommended to use inorganic sunscreen, which is less organic, and among them, it is better to use the one with fewer ingredients.
There is also a controversy over the appropriate UV protection index, which can be determined according to the user's habits and environment. If you can apply sunscreen at appropriate time intervals in a typical living environment, SPF30 or PA++ products can block UV rays well even in summer. However, SPF50+, PA+++ or higher products are recommended if UV rays are strong, exposed for a long time, or cannot be applied frequently.
This is because the amount of ultraviolet rays that touch the skin decreases by half compared to the SPF30 product, and the duration that can protect the skin when the same amount is applied is twice as long. Some say that SPF30, 60, and UV protection rates are only 96.6% and 98.3%, respectively, which are only 1.7%, so it doesn't matter what you apply, but it's twice as different from the skin's point of view. (For example, SPF 30 products transmit 3.3% of ultraviolet B, but 60 products transmit only 1.7%.)
It can be said that the right way to use sunscreen is more important than the choice of sunscreen. The most important thing is usage, and the survey found that in most cases, less than half of the quantitative amount is applied. When applied to the entire adult face, the correct amount of coating is about 1.2g, which is about a small pill of jujube. It's roughly right if you apply a little more than twice the amount you usually apply. It is also important when to apply it, but it takes time for sunscreen applied to the skin to spread evenly to a certain thickness, so it is appropriate to apply it 15-30 minutes before going out. As many people know, if possible, it is ideal to apply it once every two hours. When you apply it on top, apply only about half of the amount you applied for the first time.
Some people say that inorganic sunscreen can be used as soon as you apply it, but it does not spread evenly regardless of organic or inorganic substances, so it is recommended to apply any blocking agent 15 to 30 minutes before. Sunscreen is harder to remove than basic cosmetics because it uses a method of applying oil film to particles of sunscreen to maintain its effectiveness for a long time. Therefore, it is recommended to double wash your face with cleansing oil and cleansing foam. Otherwise, there are quite a few cases of acne or trouble.
Recently, there are many foundations and powder-type products including sunscreen. These products are helpful, but the best way is to use sunscreen before color makeup because the amount actually used on the skin is not enough to show the sunscreen effect displayed on the product. However, for women, it is not easy to apply sunscreen on time after applying makeup, so it is helpful to apply powder-type products every two hours with good basic makeup.
Since many years ago, spray-type sunscreen has been on sale because it is convenient to use. In the case of spray, it is recommended to rub and spread evenly on the skin because it does not spread evenly if you spray it on the skin and stay still. The stability of inhalation into the respiratory tract is not yet clear, and some papers have reported that lung inflammation has occurred in children, so it is better not to use it in children and be careful not to inhale it in adults.
The most controversial thing these days is the safety of sunscreen.
In particular, there was an article recently published that applying some sunscreen and tightening ultraviolet rays in a swimming pool containing chlorine results in carcinogens. Can sunscreen really turn into carcinogens? First of all, I think we can say that physical sunscreen is somewhat safe. This is because inorganic sunscreen is the principle that the metal component physically bounces off ultraviolet rays, and because it is very stable against light, it does not change easily to other components.
In the case of organic cars, there is no study showing that carcinogens are generated only when UV rays are applied or only when they enter swimming pool water containing chlorine. The problem is when chlorine and ultraviolet rays are exposed to organic cars at the same time, and in the case of a relatively widely used organic sunscreen called Avobenzone, trace amounts of chlorinated phenol and acetophenone (acetophenone) are not yet recognized carcinogens in the human body. However, there are results that damage DNA in animal experiments) is detected relatively consistently. The problem is the amount, but in most cases, trace is detected to the extent that it is difficult to measure the amount. It is still unknown whether the incidence of cancer will increase significantly even in this amount.
If it were me, I would feel free to apply some kind of sunscreen in my daily life. This is because there is no evidence that exposure to ultraviolet rays can turn into carcinogens. However, I think I will use physical sunscreen when I go to an outdoor swimming pool or water park.
In addition, the risk posed by some sunscreen is a hormonal abnormality.
Because the structure of some organic sunscreen components is similar to estrogen, when these components are absorbed into the body, they are mistaken for female hormones, resulting in poor sperm mobility in men. In fact, if you urinate after a while after applying sunscreen, a trace amount of the ingredient is detected in the urine. It means that it is absorbed by the whole body. (FYI, there is no evidence yet that physical sunscreen is absorbed by the whole body.)
But in conclusion, it can be said to be tilted. The structure is similar to estrogen, but even if applied to the exposed area every day, the amount is too small to cause abnormalities in the actual endocrine system. The larger and more well-designed studies consistently conclude that sunscreen does not cause confusion in the sex hormone system. This is all the more so in the amount we use on a daily basis.
The last question raised is whether nano-sized inorganic sunscreen is safe.
As mentioned above, the disadvantage of inorganic sunscreen is the white cast, and in order to reduce this, the size of metal particles has been reduced. The advantage of such particle nanonization is that the white cast phenomenon is reduced, but the disadvantage is that it is questionable about the reduction of UVA and safety. In particular, nano-sized ZnO (zinc oxide) will be absorbed throughout the body and affect it. (Actually, nano-sized zinc oxide cannot be used for UV protection purposes in the EU. Anyway, the EU does not grant permission for now if something is a little suspicious. I think it's very meticulous in terms of safety:) Studies have shown that nano-sized zinc oxide can damage cells when it meets cells.
However, several studies have shown that when nano-sized zinc oxide or titanium dioxide is actually applied to the human body, these inorganic sunscreen components penetrate lower than the stratum corneum, the outermost layer of the skin. A study conducted by the EU also concluded that very small amounts of zinc ions may be absorbed when zinc oxide is applied, but it is too small to affect the human body. Even in common sense, it is not easy for charged metal ions to penetrate various charged skin and go inside. In the case of nano-sized inorganic sunscreen, it is recommended to use it if you hate the white cast even if the sunscreen effect is slightly lowered among those who have sensitive skin.
What I felt while writing this article was that the more interested in health and skin, the more repulsive and misinformation you have about sunscreen. The more interested you are, the more you search, and the more you will be exposed to information that looks like the truth and makes you want to believe it. Sunblocks do much more good than harm. Each person has a different skin tone and different sensitive ingredients, so I think the most important thing is to consistently use the product that suits you the best.