Scientific Investigations Report 2006–5155
U.S. Geological Survey Scientific Investigations Report 2006–5155
By David R. Wilburn and David A. Buckingham
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This report compares estimates of U.S. apparent consumption of lead with estimates of total U.S. consumption of this mineral commodity from a materials flow perspective. The difference, attributed to the amount of lead contained in imported and exported products, was found to be significant for this sector. The study also assesses the effects of including mineral commodities incorporated in manufactured products on the interpretation of observed trends in minerals consumption and trade.
Materials flow is a systems approach to understanding what happens to the materials we use from the time a material is extracted, through its processing and manufacturing, to its ultimate disposition. The U.S. Geological Survey (USGS) provides accurate and detailed mineral production and mineral commodity consumption statistics that are essential for government, nongovernment organizations, and the public to gain a better understanding of how and where materials are used and their effect on the environment and society.
Published statistics on mineral apparent consumption are limited to estimates of consumption of raw material forms (ore, concentrate, and [or] refined metal). For this study, apparent consumption is defined as mine production + secondary refined production + imports (concentrates and refined metal) – exports (concentrates and refined metal) + adjustments for government and industry stock changes. These estimates do not account for the amount of mineral commodities contained in manufactured products that are imported to the United States, nor do they deduct the amount of these mineral commodities contained in manufactured products that are exported from the United States.
When imports or exports of manufactured products contribute significantly to the total use of a particular raw material, an estimate of consumption that does not consider the incorporated forms of these mineral commodities within imported or exported manufactured products can be either under- or overreported (depending on the net trade flow). Factors that influence consumption and trade patterns include variations in industry structure, labor or financial markets, legislation, and technology. As U.S. trade patterns of manufactured products change, omitting mineral commodities incorporated into these goods as part of U.S. mineral commodity consumption estimates may affect the interpretation of observed trends in minerals consumption and trade.
Although it may be desirable to include minerals contained in manufactured products as part of consumption estimates, collection and estimation of these data are sometimes difficult. Consumption and trade data for every traded product may not be readily available. Compiling comprehensive consumption statistics for mineral commodities, which have many end uses, each including multiple products, may be time consuming. For these reasons, studies of all mineral commodities are not feasible. Mineral commodity selection for this study is based on data accessibility considerations and the relative importance of lead contained in imported and exported products when considered part of total U.S. lead consumption.
Lead was selected for this initial evaluation of total mineral consumption because of the need to understand the consumption pattern of this potentially toxic metal and its compounds, the relative simplicity of this sector’s end-use structure, and the availability of trade data. This study draws upon the findings of an earlier lead consumption study (Biviano and others, 1999) conducted by the USGS for the period 1984 to 1993, but uses a different study methodology for an industry whose structure has changed from that considered in the earlier study.
Figure 1 shows the quantity of material contributing to U.S. total consumption of lead metal from domestic and foreign industrial sectors in 2004, based upon trade data reported by the USGS and the U.S. International Trade Commission (USITC). For this study, total consumption is defined as primary and secondary refined lead production + refined metal imports for consumption + refined lead contained in imported products – refined lead exports – refined lead contained in exported products + adjustments for government and industry stock changes. The U.S. total consumption of lead metal is the sum of U.S. production from primary refineries and secondary recyclers, refined metal imports and exports, and shipments of lead scrap into and out of the United States. Included are estimates for the amount of lead contained in manufactured products that are imported and exported (of which about 85 percent are lead-acid battery products). Changes in U.S. Government stockpiles and industry stock changes are also included. For 2004, the U.S. apparent consumption of lead metal is reported as 1.44 million metric tons (Mt) (Gabby, 2006); however, when the quantity of lead contained in imported and exported manufactured products (colored boxes) is taken into account, the total U.S. consumption of lead metal is estimated to be about 1.78 Mt. Most of the difference between the two estimates, approximately 340,000 metric tons (t), can be attributed to the inclusion of lead contained in imported and exported manufactured products in the total consumption statistics. Minor variations in data comprehensiveness and estimation methodology may also affect results.
The lead-acid battery sector is the principal end use of lead in the United States, accounting for approximately 81 percent of the reported U.S. lead consumption in 2003 (Matos and others, 2005), 83 percent in 2004 (Gabby, 2005), and 85 percent in 2005 (Gabby, 2006). Lead-acid batteries include starting-lighting-ignition batteries for vehicles (accounting for about 87 percent of lead-acid batteries by weight), stationary, uninterruptible power-supply equipment for computer and telecommunications networks and hospitals (about 8 percent), and as a source of motive power in airline ground equipment, golf carts, industrial forklifts, and mining vehicles (about 5 percent) (Battery Council International, 2005a). The lead-acid battery, similar to the automotive battery shown in figure 2, is an example of a manufactured product that can be tracked through the economy. These widely used batteries are highly recyclable, are an important component of total U.S. lead consumption, and are reported separately in trade statistics. The potential toxicity of lead-acid batteries makes quantifying the use of these products within the United States important. For these reasons, the lead-acid battery sector was selected as a case study for this lead consumption analysis.
The potentially toxic effects of lead on organisms have become widely recognized since the mid-1980s, resulting in Federal, State, and local legislation governing lead production, trade, domestic use, and disposal, which in turn have influenced lead end-use patterns, the amount of product recycling, and U.S. trade. Compliance with environmental regulations has significantly reduced or eliminated the use of lead in nonbattery applications (such as gasoline, nonmilitary ammunition, paints, solders, and water systems). Since 1989, most states have passed legislation prohibiting the disposal of lead-acid batteries in landfills and incinerators and requiring retailers to accept used batteries for recycling when consumers purchase new batteries (Battery Council International, 2005b). Lead-acid battery recovery for recycling has increased from about 70 percent in 1980 to about 93 percent in 2003 as a growing number of communities and States have restricted lead-acid batteries from disposal at landfills or combustors (U.S. Environmental Protection Agency, 2005). In 2005, the Battery Council International released a study reporting a recycling rate for lead-acid batteries of about 99 percent for the 1999 to 2003 period (Battery Council International, 2005a). While lead use in other applications has declined, the total amount of lead contained in lead-acid vehicle batteries has generally continued to grow, primarily because of increasing vehicle sales in the United States.
Analysis of Results