Lead products

Applications. The principal use for rigid polyurethane foams is for iasulation ia various forms utilized by a variety of iadustries. Lamiaates for resideatial sheatiag (1.2 to 2.5 cm thick with aluminum skins) and roofing board (2.5 to 10.0 cm thick with roofing paper skins) are the leading products with about 45 metric tons of Hquid spray systems also ia use. Metal doors iasulated by a pour-ia-place process coastitute another substantial use. 

Rigid Applications. The use of the lead stabilizers is very limited in the United States but, they are stiU used in several rigid PVC appHcations in Europe and Asia. The highest use of lead stabilizers in rigid PVC is for pipe and conduit appHcations. Tribasic lead sulfate is the primary heat stabilizer with lead stearates included to provide lubrication. The lead products are typically fully formulated, usually including lubricants and pigments for pipe extmsion appHcations. These lead one-packs, when used at about 1.8—2.5 phr, provide all of the stabilizer and lubrication needed to process the polymer. A lead one-pack contains tribasic lead sulfate, dibasic lead stearate calcium stearate, polyethylene wax, paraffin wax, ester wax, and pigments. 

Use of lead ia modem iadusttial society results from its unique physical and chemical properties. By the middle of the nineteenth century, world production of lead had risen to 1 x 10 metric tons per year, passed 1 x 10 t /yr early in the twentieth century, and reached 1.5 x 10 t /yr by midcentury. Lead production is expected to reach 5.6 x 10 t/yr by the year 2000. 

Secondary Lead. The emphasis in technological development for the lead industry in the 1990s is on secondary or recycled lead. Recovery from scrap is an important source for the lead demands of the United States and the test of the world. In the United States, over 70% of the lead requirements are satisfied by recycled lead products. The ratio of secondary to primary lead increases with increasing lead consumption for batteries. WeU-organized collecting channels are requited for a stable future for lead (see BATTERIES, SECONDARY CELLS Recycling NONFERROUS METALS). 

Table 5. World Mine and Refined Lead Production, 1(P t...

The principal U.S. lead producers, ASARCO Inc. and The Doe Run Co., account for 75% of domestic mine production and 100% of primary lead production. Both companies employ sintering/blast furnace operations at their smelters and pyrometaHurgical methods in their refineries. Domestic mine production in 1992 accounted for over 90% of the U.S. primary lead production the balance originated from the smelting of imported ores and concentrates. 

Secondary lead production made up over 70% of the lead produced in the United States in 1992 vs 54% in 1980. The amount of secondary lead produced was 698 X 10 t in 1988, 888 x 10 t in 1990, and 878 x 10 t in 1992. Of the 1.2 x 10 t of lead consumed in the United States in 1992, approximately 880,000 t were produced from the recycling of lead—acid batteries and 350,000 t from primary sources. A similar trend exists worldwide. In 1992, for the first time, slightly over half (51%) of the lead produced in the world came from secondary sources. 

In determining the purity or percentage of lead in lead and lead-base alloys, the impurities or minor components are deterrnined and the lead content calculated by difference. Quality control in lead production requires that the concentration of impurities meet standard ASTM specifications B29 (see Table 7). Analyses of the individual impurities are performed using various wet chemical procedures and instmmental methods such as emission spectroscopy. 

Trade association of manufacturers of lead products and lead components mining companies, smelters and refiners of lead. Provides lead information to consumer s and is a clearinghouse for lead recycling information. 

The U.S. is the world s largest recycler of lead scrap and is able to meet about 72% of its total refined lead production needs from scrap recycling. The secondary lead industry consists of 16 companies that operate 23 battery breakers-smelters with capacities of between 10,000 and 120,000 t/yr five smaller operations with capacities between 6000 and 10,000 t/yr and 15 smaller plants that produce mainly specialty alloys for solders, brass and bronze ingots, and miscellaneous uses. 

FIGURE 3.4 Primary lead production process. (From U.S. EPA, Profile of the Nonferrous Metals Industry, publication EPA/310-R-95-010, U.S. EPA, Washington, DC, September 1995.)... 

The metal casting industry conventionally divides casting products into ferrous and nonferrous metals, in particular, iron-based, steel-based, aluminum-based, and copper-based castings. The other castings of low fractions include magnesium, lead, zinc, and their alloys. In the U.S., the foundry industry currently produces 11 million tons of metal product per year, with a shipment value of 19 billion. Of them, iron and steel accounted for 84% of metals cast.5 The remaining 15% of foundry operations are concerned with aluminum, copper, zinc, and lead production. Table 4.2 summarizes critical physical and thermal properties of aluminum, iron/steel, and cast iron. 

A cohort mortality study was conducted to compare the mortality rates due to chronic renal disease in 4,519 battery plant workers and 2,300 lead production or smelter workers from 1947 to 1980 (Cooper 1988 Cooper et al. 1985). The mortality data for these workers were compared with national mortality rates for white males. Environmental lead levels and PbB levels were available for only about 30% of all workers for varying time periods from 1947 to 1972. Statistically significant increases in mortality from "other hypertensive disease" and "chronic nephritis" were seen in both lead cohorts. Limitations of this study include the fact that various confounding factors, such as smoking, were not accounted for, and the workers were probably exposed to other toxic chemicals. 

Domestic lead metal production rose at an annual rate of 1.3% between 1990 and 1996, going from 1.33 million metric tons to a record high of 1.43 million metric tons. Primary lead production declined at an annual average rate of 3.2% during this time period, dropping from 404,000 metric tons in 1990 to... 

Although certain uses of lead preclude recycling (e g., use as a gasoline additive), lead has a higher recycling rate than any other metal (Larrabee 1998). An estimated 90-95% of the lead consumed in the United States is considered to be recyclable. In the United States, 77.1% of the lead requirements were satisfied by recycled lead products (mostly lead-acid batteries) in 1996. This compares to 69.5% in 1990 and 55.2% in 1980 (Larrabee 1997, 1998). 

Of the known aquatic releases of lead, the largest ones are from the steel and iron industries and lead production and processing operations (EPA 1982a). Urban runoff and atmospheric deposition are significant indirect sources of lead found in the aquatic environment. Lead reaching surface waters is sorbed to suspended solids and sediments (EPA 1982a). 

Cooper WC. 1981. Mortality in employees of lead production facilities and lead battery plants, 1971-1975. In Lynam DR, et al. eds. Environmental Lead Proceedings of the Second International Symposium on Environmental Lead Research, December, 1978, Cincinnati, OH. New York, NY Academic Press, 111-143. 

Cooper WC. 1988. Deaths from chronic renal disease in US battery and lead production workers. Environ Health Perspect 78 61-63. 

Mehta FR. 1990. Lead absorption in workers handling lead products. Indian J Ind Med 36 15-20. 

Hasrat JA, De Bruyne T, De Backer JP, Vauquelin G, Vlietinck AJ. Isoquinoline derivatives isolated from the fruit of Annona muricata as 5-HTergic 5-HT1A receptor agonists in rats unexploited antidepressive (lead) products. J Pharm Pharmacol 1997 49 1145-1149. 

Second, we analyse the position of the leading products in the different therapeutic and generic drug markets. Our aim is to evaluate the extent to which the leaders achieve dominant positions in each market. Positions of dominance are shown in terms of the market share of the most frequendy prescribed active ingredient, product or presentation in its therapeutic group of active ingredients, products or presentations, called v, in which g = 1,2,..., G are mutually exclusive groups. 

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