 Patterson examined the levels of lead in the common environment and in deeper parts of the oceans and Antarctic ice, showing that lead had only been brought to the surface in recent times.He would discover that the higher levels of lead were from the use of tetraethyllead in leaded gasoline, despite long-established claims by Robert A. Kehoe and others that this chemical was safe.Patterson would continue to campaign against the use of lead, ultimately resulting in government-mandated restrictions on the use of lead.