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IPEN Body Burden Community Monitoring Handbook OrganometalsOrganolead Compounds Chemical Name: Alkyllead compounds may be confined to tetramethyllead (TML, Pb(CH3)4) and tetraethyllead (TEL, Pb(C2H5)4). CAS Number: 75-74-1 (TML) and 78-00-2 (TEL). Properties: Solubility in water: 17.9 mg/L (TML) and 0.29 mg/L (TEL) at 25°C; vapour pressure: 22.5 and 0.15 mm Hg at 20°C for TML and TEL, respectively; log KOW: Discovery/Uses: Tetramethyl and tetraethyllead are widely used as “anti-knocking” additives in gasoline. The release of TML and TEL are drastically reduced with the introduction of unleaded gasoline in late 70’s in USA and followed by other parts of the world. However, leaded gasoline is still available which contribute to the emission of TEL and to a less extent TML to the environment. Persistence/Fate: Under environmental conditions such as in air or in aqueous solution, dealkylation occurs to produce the less alkylated forms and finally to inorganic lead. However, there is limited evidence that under some circumstances, natural methylation of lead salts may occur. Minimal bioaccumulations were observed for TEL in shrimps (650x), mussels (120x) and plaice (130x) and for TML in shrimps (20x), mussels (170x), and plaice (60x). Toxicity: Lead and lead compounds has been found to cause cancer in the respiratory and digestive systems of workers in lead battery and smelter plants. However, tetra-alkyllead compounds have not been sufficiently tested for the evidence of carcinogenicity. Acute toxicity of TEL and TML are moderate in mammals and high for aquatic biota. LD50 (rat, oral) for TEL is 35 mg Pb/kg and 108 mg Pb/kg for TML. LC50 (fish, 96hrs) for TEL is 0.02 mg/kg and for TML is 0.11 mg/kg. Source: UNEP Chemicals, Regional Reports of the Regionally Based Assessment of Persistent Toxic Substances Program (2002) Available from: http://www.chem.unep.ch/pts UNEP Chemicals 11-13, chemin des Anemones CH-1219 Chatelaine, GE Switzerland. 
IPEN Body Burden Community Monitoring Handbook - 2003 |
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