Lead

Uses of lead

The largest use of lead is within lead-acid batteries, accounting for 85 percent of lead consumption in 1995. Lead is also used in a very wide range of other products, including ammunition, glass, covering for cables, building construction materials, plumbing, solder, electrical and electronic components, pesticides, pigments, radiation shielding, and bearing metals. About 40-50 percent of lead used is recovered and recycled. Lead is the fifth most important metal, in terms of usage, in the US economy.

Lead is now banned for use within many products in the U.S. These bans typically involve restricting the amount of lead in the product to a certain low percentage, not removing it entirely. The most well-known example is leaded gasoline -- banning lead in gasoline has reduced environmental lead levels dramatically. Lead has also been restricted for use within paint and more recently within solder used in food packaging cans. There are also restrictions on lead used in plumbing pipes.

Health Effects

Lead can cause a variety of human health effects. Even at low levels, childhood lead exposure can cause delays in normal physical and mental development and deficits in hearing and learning abilities, often represented as a loss of "IQ". Chronic exposure has been linked to human cerebrovascular, kidney, reproductive, and neurological disease. Exposure of pregnant women can cause premature birth, low birth weight, or abortion. Certain compounds of lead are carcinogens. Lead accumulates in the human body in blood, bone, and soft tissue, but most of it is stored in bone.

In The Environment

Lead in air attaches to dust, and can be carried for long distances. It is usually retained in the upper level of soil, where it is expected to slowly be bound into insoluable salts. However, a heavy rain can wash some of it into water. Soil near hazardous waste sites or near areas with heavy automobile traffic can have high levels of lead; this can be taken up by plants or cause human exposure to children that play in the soil. Breathing lead dust in the air is another source of exposure. Ingestion of lead can occur through food, water (especially from corrosion of lead-based pipes), or dirt or paint chips swallowed by children.

Lead does not appear to bioconcentrate significantly in fish but does in some shellfish such as mussels. Lead shot and fishing wieghts can poison waterfowl; a bird may die of acute lead poisoning from ingesting 6 shot pellets, or chronic lead poisoning from even fewer.

Sources

Natural sources such as soil weathering or volcanoes are small in comparison to human (anthropogenic) ones.

The major sources of lead air releases are primary lead smelting (17 percent), non-municipal incineration (14 percent), aircraft fuel (14 percent), secondary lead smelting (11 percent), and miscellaneous fuel burning (10 percent). The major known sources of lead land disposal from TRI are primary lead and zinc smelting facilities (49 percent), secondary nonferrous metals (32 percent), primary copper (26 percent), steel mills (15 percent), and glass pressing and blowing (10 percent). The largest source by far used to be cars using leaded gasoline, but with the almost total elimination of this use, stationary sources now predominate.

Estimates of nationwide production, use, and release of lead in 1995 are:

• Primary production from mines in the U.S. was 827,000 tons. Secondary production, mainly from scrapped lead-acid batteries, was 2,148,000 tons. The United States had 15 percent of the world's production.

• Consumption (use) of lead was 3,536,000 tons. Of this, 3 million tons were used for storage batteries. The next largest single use was for ammunition, with 157,000 tons.

• EPA estimates that 1995 lead air releases were 3,943 tons, including both stationary and mobile sources. Land and water releases are not as well characterized.

• EPA's Toxic Release Inventory (TRI), which includes only manufacturing and Federal sources, reveals a large amount of lead land disposal. 1995 TRI lists 7,342 tons of land releases, 1,013 tons of air releases, and 31 tons of water releases. There were also 191,000 tons of transfers of lead: 177,500 tons to recycling, and 13,500 tons to disposal. Lead land disposal offsite totaled 12,270 tons.

• There were 34,800,000 tons of RCRA hazardous waste that contained lead generated in 1995. However, the percentage of this waste that consisted of lead as opposed to other ingredients is not known.

References

* Environmental Protection Agency. National Air Pollutant Emission Trends, 1900-1996. Office of Air Quality Planning and Standards. EPA-454/R-97-011. December 1997.

* Environmental Protection Agency. National Air Quality and Emissions Trend Report, 1996. Office of Air Quality Planning and Standards. EPA-454/R-97-013. December 1997.

* Environmental Protection Agency. National Primary Drinking Water Regulations: Technical Factsheet on Lead. Office of Ground Water and Drinking Water. January 1998.

* Agency for Toxic Substances Disease Registry. Public Health Statement on Lead. June 1990.

* U.S. Department of the Interior. Minerals Yearbook Volume 1. U.S. Geological Survey. "Lead" written by Gerald R. Smith. 1995.

* Environment Canada. Factsheet: Lead poisoning of water birds. CW69-4/96-1996E. 1996.

* Environmental Protection Agency. Toxic Release Inventory Database (1996 "frozen" version).

* Environmental Protection Agency. Biennial Reporting System Database (1995 final version).

Detailed Sources of Lead Emissions

Air releases of lead, 1995 (Source: Table A-6, EPA's National Air Pollutant Emission Trends)

Land disposal of lead -- Top 15 Industry Totals

(Source: 1995 TRI, manufacturing sources only. Facilities were classified by their first SIC code, so some lead may be incorrectly classed if it was associated with a secondary SIC code at a facility. Land disposal can be onsite, at the manufacturing plant, or offsite at a commercial land disposal facility. Land disposal methods include landfills, solidification/stabilization, land farming, and surface impoundment.)