Halogens (salt builders, Greek "hals," salt) directly bind with metals, therefore without the participation of acids, salts. The most important halogens are chlorine, bromine, fluorine and iodine. They appear in cosmetics in word components such as chloro, bromo, fluoro and iodo. They all possess a preservation and antimicrobial effect. They are even components in nature and different circulation also important for human beings. One knows also that they are extremely reactive, toxic and can damage cells. Preserving cosmetic components made on the basis of halogens (such as bromo-chlorophene, chloroacetamide, chlorobutanol, chlorophene, chloroxylene oil, chlorphensine, methylclhloroisophthiazolinone 2-bromo-2-nitro-1, 3 dioxane) and the many iodine complexes such as iodopropynyl butylcarbamate can be allergenic, protein and DNA changing and are generally hazardous to health, and are nevertheless encounter in many cosmetics. They can be absorbed into the skin, remain there, cause destruction and damage. The halogen organic compounds are also therefore to be expressly avoided because they can create cancer-causing nitrosamines.

Chemical preservative, can be allergenic. Halogen-organic connection.