Because of the variety of different substances found together in electroscrap, incineration is particularly dangerous. For instance, copper is a catalyst for dioxin formation when flame-retardants are incinerated. The introduction of WEEE into incinerators results in high concentrations of metals, including heavy metals, in the slag, in the fly ash, the flue gas and in the filter cake. Municipal incineration is the largest point source of dioxins into the US and Canadian environments and among the largest point source of heavy metal contamination of the atmosphere.
Some producers send their electroscrap to cement kilns for use as an alternative to fuel.
Smelting can present dangers similar to incineration. Indeed, there have been concerns expressed that the Noranda Smelter in Quebec, where much of the North American electroscrap is sent, is producing dioxins due to the residual presence of PVC or other plastics in the scrap. Noranda has denied that their smelter presents a pollution hazard. It has become common knowledge that all landfills leak. The situation is far worse for older or less stringent dump sites.