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San Joaquin County Community Diesel Engine Emission Control Technologies <br /> Development Department <br /> oxide is the primary form found in the exhaust although cerium can also form <br /> salts. Oxides and hydroxides of cerium are poorly soluble in body fluids and are <br /> slow to clear from the organism. Nitrates,phosphates and chlorides have <br /> intermediate solubility and have clearance times up to several weeks. Sulfates <br /> and sulfides are easily soluble and clear from an organism within days. Cerium <br /> can affect the respiratory tract and associated lymph nodes(inhalation exposure) <br /> and once in the circulatory system can partition to the skeleton,liver,kidney and <br /> spleen. Studies subjecting animals to large dosages of cerium show evidence of <br /> neurological effects,possibly due to cerium competing with calcium binding <br /> sites in the brain. Long term human expose to cerium is correlated with rare <br /> earth pneumoconiosis,but the precise role of cerium in this disease is not well <br /> characterized due to confounding metal aerosols (HEI Attachment A,HEI <br /> Communication 9 2001,DieselNet 2002.02b,Mayer 1998,Mayer 1999). Effects <br /> of nano-particulate cerium oxide are unknown(Mayer 2002). However, <br /> projections show the environmental exposure to cerium from fuel additives will <br /> be orders of magnitude below occupational exposure limits. Further research is <br /> necessary to identify the size of emitted particles containing cerium,potential <br /> developmental and neurotoxic effects of cerium particles, the effects of engine <br /> aging and regeneration on emissions of cerium and the chronic effects of inhaled <br /> cerium particles in emissions on target organs (HEI Communication 9 2001;HEI <br /> Attachment A). <br /> Copper Based Additives <br /> Description: Copper will decrease PM emissions, lower the soot combustion <br /> temperature and facilitate filter regeneration. As with other additives, when used <br /> in conjunction with DPFs,the higher the additive concentration the greater the <br /> filter pressure drop due to ash accumulation and the greater the operating costs of <br /> the system. Copper platinum blends dropped balance temperature for trap <br /> systems from 537-557°C to 347°C. There are significant problems with copper- <br /> based additives. They can cause severe fouling of fuel injectors and cyclic soot <br /> loading of the filter yielding high temperature peaks during regeneration. Some <br /> ceramic fiber wound filters were determined to be incompatible with copper <br /> based additives as the high regeneration temperatures caused glazing of the <br /> copper and oil ash resulting in bonding of the fibers and decreased filter <br /> durability. Copper-based additives result in dioxin and furane emissions <br /> ., (DieselNet 2000.02b,Mayer 1998,Mayer 1999). <br /> Fate and Transport: Some fate and transport studies address environmental <br /> risks from copper. Copper is toxic to certain species,but more importantly, <br /> coppers additives result in the deleterious secondary emissions of furanes and <br /> dioxins. This precludes them from further consideration(DieselNet 2000.02b„ <br /> Mayer 1998). <br /> DeSilva Gates Quarry Project <br /> Draft Environmental Impact Report L-7 <br /> As 05105.05 <br /> r <br />