One of the main characteristics of WEEE is that it contains substances (lead, cadmium, mercury, chromium and persistent organic compounds) that, due to their properties, can cause toxic effects on health and the environment if not handled properly. It also contains substances with a high economic value (palladium, gold, silver, copper, ruthenium, indium, etc.) that can be recycled and reincorporated as raw material for new products. A group of hazardous substances contained in WEEE are halogenated flame retardants, such as polybrominated biphenyls (PBB), polychlorinated biphenyls (PCB) and polybrominated diphenyl ethers (PBDE). These compounds were incorporated into the Stockholm Convention (EC) in 2009, to which Mexico and 180 other countries are party. In addition to PBDEs, the best practice approach covers other significant contaminants potentially present in WEEE, consisting primarily of various heavy metals, such as lead, mercury, cadmium, among others; as well as the so-called rare earths and other elements such as beryllium, antimony, among others. There are other categories of contaminants such as ozone-depleting substances, or gases classified as greenhouse gases. Generally, these contaminants are found in a particular and practically limited way to one category of WEEE, represented by heat exchange equipment such as refrigerators and air conditioning equipment, among others containing chlorofluorocarbons (CFCs) and hydrochlorofluorocarbons (HCFCs). The environmentally sound management of WEEE must obviously contemplate the consideration with a comprehensive approach of all the contaminants present in them, as well as their maximum level of use; said contaminants are presented in the following table: