The Personal Care Product Council’s online ingredient dictionary, the wINCI, defines chelating agents or sequestrants1 as “ingredients that complex with and inactivate metallic ions to prevent their adverse effects on the stability or appearance of cosmetic products.”2 Metallic impurities can come from many different sources, primarily from either the ingredients themselves—specifically those that are naturally derived, the water system, or minute extractions from metallic equipment and storage containers. If not deactivated, these metallic ions can deteriorate cosmetic products by reducing clarity, compromising fragrance integrity and causing rancidity/oxidation.
The mechanism for chelation, described as a chelate complex, is based on multiple bonding (polydentate ligand) around a single central atom. Common chelating agents include ethylenediaminetetraacetic acid (EDTA) and its derivatives, etidronic acid and its derivatives, galactaric acid, sodium metasilicate and phosphate derivatives. Disodium EDTA and tetrasodium EDTA are two popular chelators used in the US personal care industry. Chelators are used in almost
Chelators are used in almost every personal care formulation type to increase effectiveness and improve stability, thereby improving consumer acceptance. In addition, they have demonstrated the ability to boost preservative activity. Chelators are used in liquid soap and body wash to prevent fragrance and color degradation and for their synergistic effect with antimicrobials. They are also incorporated into bar soap to prevent rancidity, softening, brown-spotting, cracking and discoloration due to metal ions, as well as to enhance foaming and rinsability.
In creams and lotions, again they are used to prevent rancidity, the discoloration particularly of organic dyes, off-odors and the degradation of active ingredients, in addition to improving the shelf life and efficacy of vitamins, essential oils and fatty acids. In wipes, chelators prevent fragrance degradation and provide preservation protection. In deodorants and antiperspirants, they prevent fragrance degradation and provide antioxidant protection, particularly when formulated with botanical actives and vitamins.
Finally, in shampoos and conditioners, chelators prevent fragrance and color degradation, haze formation and precipitation, and again, they provide a synergistic effect with antimicrobials; in coloring shampoos, they preserve formulation stability in addition to stabilizing tint and color intensity by stabilizing the redox system. Another potential use is for the neutralization of reactive oxygen species (ROS) that are generated by iron or other metal catalysts upon exposure to ultraviolet (UV) radiation, which can induce cutaneous pathologies such as skin cancer, photosensitization and photoaging.3