Overview
Mercury is a heavy metal that is liquid at room temperature and toxic in all its common forms. It harms the nervous system and travels long distances through air and water, which is why it is controlled both in products and by international treaty.
Where it's restricted
Under RoHS mercury is capped at 0.1 percent by weight per homogeneous material. It is also restricted in vehicles under ELV.
Beyond product rules, mercury is one of the most tightly controlled substances globally. The Minamata Convention sets worldwide obligations to cut mercury use and emissions, and the EU puts those into effect through the EU Mercury Regulation.
Typical uses
Most electronics applications are now historical. Mercury was used in fluorescent lamps, in switches and relays, and in some sensors. Phase-outs and bans have removed it from most new designs.
Mercury sits under both product law and a dedicated global treaty. Compliance often means checking RoHS, ELV and the Mercury Regulation together.
Note: this is general educational information and not legal advice. Always check the official source before relying on it.