Tetraethyllead (common name tetraethyl lead), abbreviated TEL, is an organolead compound with the formula (CH3CH2)4Pb. An inexpensive additive, its addition to gasoline (petrol) from the 1920’s allowed octane ratings and thus engine compression to be boosted significantly, increasing power and fuel economy. TEL was phased out because of the toxicity of lead and its deleterious effect on catalytic converters. It is still used as an additive in aviation fuel for piston engine-powered aircraft. (Wikipedia)
The Ethyl company, now known as Innospec, is the world’s only remaining manufacturer of TEL.
In a 2010 investigation by The Guardian and Guardian Films, Innospec, while trading as company Octel, was revealed to have been bribing officials in Iraq and Indonesia with millions of dollars to continue using TEL as a fuel additive, which has links to causing to brain damage in children. The company has since settled this matter with all of the authorities, and has a new management team in place who have introduced new compliance procedures.