In addition, it must be pointed out that people's skin color has a lot to do with race and genetic factors.
There are melanocytes in the basal cell layer of human skin epidermis Melanocytes contain tyrosinase, which can oxidize tyrosine to form melanosome. This kind of cell particle is the key factor to determine skin color, which can't be changed by any cosmetics. Some advertisements claim that cosmetics with the functions of "whitening" and "removing spots" are just temporarily covering up skin color. With the increase of age, collagen fibers and elastic fibers in subcutaneous tissue will gradually age and lose elasticity. No cosmetics can reverse the aging process of skin. Even cosmetics with anti-wrinkle cream added with vitamin A acid can only reduce wrinkles to a certain extent, but they will never disappear. In a word, using cosmetics can beautify the face, but this is temporary. At present, there is no cosmetic that can remain young forever after use.
Chemical composition and classification of cosmetics
Among the cosmetics sold in China, there are more than 200 kinds of chemical raw materials used by domestic manufacturers and more than 500 kinds of chemical raw materials used by importers. The chemical components of cosmetics mainly include oil ester, wax, fatty acid, alcohol, emulsifier, preservative (aldehyde), essence, organic solvent, hydrolyzed protein salt, acid, alkali, inorganic salt and so on. Some cosmetics also add a certain amount of nutritional tonics and drugs (including traditional Chinese medicine and even hormones). There are many kinds of cosmetics, and there is no clear and unified classification standard. It can be roughly divided into four categories: skin care, hair care, beauty and curative effect.
Regulations on Hygienic Management of Cosmetics
General cosmetics production technology and equipment are relatively simple, with small investment, large market demand and fast investment, so there are many varieties and great competition. Unqualified cosmetics are also easy to enter the market. In order to safeguard the interests of consumers and ensure people's health and safety, the production and sale of cosmetics must have hygienic inspection standards. Hygienic inspection of cosmetics includes the following aspects: specification of raw material selection, determination of harmful and toxic residues, microbial content and toxicological indicators (see table). The specific data requirements of some health inspection standards are similar to those of medicines and foods.