1 paroxysmal Pertaining to or marked by paroxysm; caused by paroxysms or convulsions of nature. 2  paroxysmal Specifically In geology: Relating to or produced by a violent convulsion of nature.
Inorganic lead compounds are Group 2A - Probably carcinogenic to humans. American Conference for Governmental Industrial Hygienists (ACGIH): A3 - Confirmed animal carcinogen. Teratogenicity / Embryotoxicity: DEVELOPMENTAL HAZARD. May harm the unborn child. Known to cause: learning disabilities, effects on behaviour.
Lead. Lead is a soft, heavy, dull gray metal with low tensile strength. It is used in making type, for covering electrical cables, and in many alloys. The organic lead compound tetraethyl lead, Pb(C 2 H 5) 4, was widely used as a gasoline additive to prevent knock in automobile until concern about lead toxicity caused that use to be discontinued.