Paste: cosmetics: Crisis on your face?

Cosmetics: Crisis on the face?

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Scientific squirrel published on
Author: lalunasun

According to my daily life experience, most people have limited knowledge about cosmetics and many misunderstandings. We often see people talking about cosmetics as a matter of color, and their prejudice is not even out of fear of substandard cosmetics, it is a kind of preconceived impression that long-term use of cosmetics will accumulate "toxicity" in the skin, and even think that the chemical components in cosmetics will absorb blood, cycle the whole body, and poison the major organs.

Ms. Ma Yue-ling's article on her official website can be described as a result of this point: "A beauty-loving woman will put a large amount of chemical cosmetics on her face for a long time, day and night. Do you dare to eat these chemicals ?...... The skin on the face is associated with the body. Cosmetics coated with the skin can be absorbed by the blood vessels under the skin, and then gradually hurt people's liver, kidney and brain through blood circulation. Originally, everything that enters the human body's blood must first pass through the gastrointestinal tract, a unique epidemic prevention system of the human body ....... The cosmetics coated on the face may enter the blood without any choice or protection, and then hurt the body. Especially for some women who have been doing facial beauty all the year round ,...... There are many problems in the blood, some with high blood viscosity, some with high blood fat, some with abnormal hemoglobin, platelet and other indicators, which are related to too many impurities in their blood. This serious pollution of internal circulation, not only the damage to all organs in the body, but also the contaminated impurities will be congested in the meridian, resulting in a high probability of suffering from various tumors ."

I admit that it is not easy to refute such a passage-if every sentence is incorrect-but I am willing to commit myself to it. Let's start with the skin and the gastrointestinal tract.

Skin is the first line of defense against immunity
Our digestive tract consists of the mouth, swallow, esophagus, stomach, duodenal, intestinal, colon, and large intestine. The digestive juice contains digestive enzymes and a small amount of bactericidal enzymes. Some of the food we eat is decomposed into small molecules and then absorbed; those that cannot be decomposed, such as cellulose, will be discharged. Although the normal physiological function of the digestive tract also contains immunity, it is mainly used to defend against microbial pathogens. For small chemical molecules, the intestinal defense function is limited. It cannot selectively only absorb substances that are beneficial to the organ and not harmful substances-otherwise, how can many foods be poisoned? Ms. Ma yueling's strong hopes for the gastrointestinal tract are doomed to become wishful thinking.

Compared to the digestive tract, the skin is more like a powerful wall. What is put on the skin, its skin absorption is extremely limited. This is closely related to the structure and properties of the skin.

In this figure, we can clearly see the hair and other ancillary structures, the skin, as well as the dermis and its internal vascular nerves. The next figure further shows the structure of the skin.

 

The epidermis is protected by Keratin (5-20 layers of dead cells, which are filled with keratin fibers that are insoluble in water but can be combined with a large amount of water) transparent layer (with stronger protection capability than the stratum corneum) and granular layer (absorbing moisture from the outside, and preventing water from penetrating inside) the spine cell layer (the cells flow through the dermis lymph), the base layer (derived from the nutrition in the upper dermis capillary) these five parts. Under these five layers is the dermis, which contains the distribution of capillary, neural, lymphatic vessels, sweat glands, hair follicles, and sebaceous glands.

The road to blood from the small and small molecules used for external use on the skin is really tortuous. First, most of them will be blocked by the dense stratum corneum. Only a few of them can squeeze into the epidermis from the gap of the stratum corneum. A small portion of fat-soluble products can penetrate through the cell membrane of the stratum corneum and then penetrate through other layers of the epidermis; A very good person may be able to sneak in from the hair follicle opening, pass through the hair follicle, and then pass through the sebaceous gland or the hair follicle wall ...... After dozens of levels, there are no more molecules that can enter the dermis layer. It is even more negligible to enter the blood layer.

Cosmetic, percutaneous removal of blood is not an objective, safety evaluation of its own standards

Cosmetics are intended for the Human Surface skin and its ancillary organs (such as hair and nails). [1] It is designed to play a role in the most peripheral part of the human body, it does not need to go deep into the body or reach a certain internal organ.

Let's take a look at skin care products for skin conditioning. Large molecules like mineral oil, hyaluronic acid, and collagen can only cover the surface of the skin. Like a "lid", they can absorb and lock water. Other major small molecules, it is indeed more or less capable of penetrating the skin. Even so, the structure of the skin has determined that the skin absorption of skin care products is extremely limited.

Even with a small amount of components, there is almost no need to worry about the safety of those components. "Almost" is because, indeed, a small number of people are sensitive to spices, preservatives, and other ingredients in cosmetics, or the stratum corneum is too thin to withstand the weakening of the barrier by Trace alcohol, in addition, the quality of some unqualified products is considered.

In fact, some people worry about harmful components entering the body. What worries about the body is that the nutrients cannot pass through. Junyi skin care investigator almost made a variety of techniques to enhance the skin penetration: first increase the water content of the stratum corneum, and then use components with low polarity and good affinity with the skin, if this is not the case, you can use a promotional material or a new dosage form, such as lipid. What are the results? The active ingredients are still almost inaccessible to the dermis-today, only the injection or botox can be used to smooth wrinkles. It's just a dream to stimulate the synthesis of a variety of proteins in the dermis by applying active ingredients. It can be said that the skin is also the skin, defeat also the skin.

Make-up products is another big block of cosmetics that plays a nutritional role in skin care products (skincare products) [2] What is the possibility of subcutaneous access?

Make-up products are based on grease, such as lipsticks, and those with powder raw materials, such as foundation and eye shadows. Whether it is grease or powder, they have large particles and are not chemically friendly to the skin. They really do not "enter the door of the Skin ". At most, there will be a very small amount of powder stuck in the pore opening, but will not continue to inwards. Surface active agents, pigments, spices, preservatives, etc. Although the molecule is slightly smaller, it is only exposed to the skin surface. On the one hand, the continuous matrix (powder and grease) hinders the inner path of other components. On the other hand, if the product is designed to be used only outside the skin, some components may enter the skin, R & D personnel will add additional anti-osmotic agents to the product, it is equivalent to plating a film on the skin. A typical example of this is some sunscreen containing avobenzone. Interested readers can look at the sunscreen composition table by themselves.

Cosmetics have an independent set of safety evaluation standards and methods. In China, all cosmetics need to undergo sixteen tests in five major stages, including acute/subchronic oral toxicity tests-although cosmetics do not taste well, but it's okay for adults to eat a few mouthfuls. Some effective components are even simulated or similar components of the skin. For example, the sub-resources used in moisturizing products, such as sharks and Ceramide, are essential for maintaining normal physiological functions of the skin. In general, it may not be as unhealthy or even less dangerous as barbecues or salted fish to compare cosmetics with food like Ms Ma.

In addition to oral toxicity, cosmetic skin toxicity, irritation, mutation-induced carcinogenic, etc. must be fully taken into account. If cosmetics "increase the chance of suffering from a certain tumor", why are there no restrictions or prohibitions on the use of cosmetics in various countries or regions? At least like a cigarette, it is mandatory to print "cosmetic is harmful to health" on the cosmetic packaging.

To sum up, there is no need to worry about blood poisoning of qualified cosmetics. Ma yueling's point of view on digestive tract and cosmetics is nonsense. Aging of the skin is a constant process. The sooner you start protecting it in the right way, the longer it will take. It would be a pity to reject cosmetics for "harmful to the human body", "lipsticks containing lead may cause cancer" and other reasons without evidence. After all, beauty and health are worth it.

References
[1] cosmetic science, Ji shixiang
[2] cosmetics of Wikipedia