Mercury

Mercury is used in many electrical and electronic applications because it is both very mobile and a good conductor. Typical traditional applications are in contact thermometers, tilt switches and of course batteries. It is also widely used in lighting applications including fluorescent tubes and mercury vapour lamps.

See the Where do RoHS Materials Occur? section of this toolkit for more details.

Because the undesirable properties of mercury have been known for many years, a lot of work has been undertaken already to either replace the element or, where this is not immediately possible, to reduce the levels used.

• Lighting
  Mercury is a key ingredient of fluorescent lighting tubes and it is used to generate the ultraviolet light which excites the phosphor coating of the tube to give the visible light. There do not appear to be viable alternatives for this application, although manufacturers have managed to reduce the quantity of mercury needed per tube. Exemption for the use of Mercury in certain lighting application do exist in the RoHS Directive.
  
  
• Batteries
  Mercury was key ingredient of various types of batteries although most manufacturers have been able to produce mercury-free zinc carbon and alkaline manganese batteries for some time. It is likely that mercury based button cells such as those used in hearing aids and some military applications will continue to be manufactured. The disposal of batteries will be addressed by the forthcoming Batteries Directive.

Summary - mercury