A toxin is generally defined as a substance that has the potential to damage or kill. The response depends upon dose (concentration), exposure pathway and assimilation, and may vary from organism to organism.

Both the US Environmental Protection Agency and the UN Environment Programme maintain active lists of known toxins. The European Commission has Directives on Waste Electrical and Electronic Equipment (WEEE) and Restriction in Hazardous Substances in Electrical and Electronic Equipment (RoHS).

A life cycle study will list potential toxins. An understanding of the supply chain will indicate potential areas where toxins may be present.