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SOURCES OF LEAD

How did lead get into the environment?  Major sources of lead  Other sources  References

How did lead get into the environment?

During the last 100 years, lead was added to many U.S. products including paint, gasoline, water pipes and health care supplies. About 330 million tons of lead were mined for these purposes. Even though lead's use is now restricted and regulated because of known health risks, the heavy metal is still mined and added to products.

Because it does not break down, most of the lead ever produced remains in soil, dust and other environs. The odorless, colorless, tastless metal so widely present in homes, yards and workplaces can only be detected through chemical analysis.

In most U.S. communities, the major sources of lead are old, peeling lead-based paint, contaminated soil and dust, drinking water and household products.

The two biggest contributors of lead to the envionment are leaded paint and gasoline. Leaded paint use peaked in the 1920s and gradually fell off until its ban in 1978. At its zenith in the 1970s and before its use was restricted in 1986, leaded gasoline spewed up to 250,000 tons of lead per year into the environment.

Major sources of lead

• Paint. Between 1920 and 1950 paint contained lead. Although most manufacturers had phased lead out of their products by the 1950s, mandatory paint lead bans were not enacted until 1978. Today, many who live in older homes are still exposed to lead inside the house when walls crack, paint peels or renovations are done and outside by soil and dust near the foundation that is contaminated with leaded paint chips. (Protection tips)
• Gasoline. Leaded gasoline was used in the U.S. from 1923 to 1986. A rapid government phase out ended the use of this anti-knock additive and ushered in the era of unleaded gasoline. (see the online article Bad decisions again and again for a brief look at lead in the environment and a history of lead in gasoline).

  Environmental lead contamination from gas peaked in the 1970s when more than 205,000 tons of lead per year were put into the atmosphere . By 1990, lead released from gas fell to 520 tons (1-3). Today, most of this lead is concentrated in soil and dirt near major freeways and busy intersections in most U.S. cities. Eating soil and breathing the dust puts many, especially children who play and live in these areas, at risk for lead poisoning each year. (Protection tips)

• Food and drink cans. Between 1976 and 1991, one of the top three major sources of lead exposure in the general population was from soldered cans (1). Lead leached from the lead solder, used to hold the can together, into the food and was consumed by anyone who ate the product. In 1980, 47% of food and soft drink cans were lead soldered, while in 1990 only 0.85% of cans were lead soldered. Since November 1991, lead soldered cans are no longer made in the U.S., but exposure can still occur with food imported from other countries with less strict standards. (Protection tips)
• Lead pipes. Lead leaches into drinking water supplies from lead water pipes and lead solder used on the pipes. Incentive programs in the 1980s reduced the use of lead pipes and products that carry drinking water. Treating water to reduce pipe corrosion in existing lines also reduced lead content in drinking water. (Protection tips)
• Consumer products. Many cosmetics and other nonfood consumer goods still contain large amounts of lead. In a recent study (4), Howard Mielke of Xavier University of Louisiana, reported that several types of lead-based hair coloring products contained lead acetate levels between 2,300 and 6,000 micrograms of lead per gram. After its use, hands, faucets, combs and other articles were coated with dangerous amounts of lead that could be transferred from surfaces and ingested by anyone who comes into contact with it. (Protection tips)

Other sources of lead

• contaminated cooking utensils
• ethnic medicines
• lead batteries
• primary batteries, wet and dry
• valve and pipe fittings
• pottery
• automobile parts and accessories
• hobby sources of lead
  • firing ranges, casting ammunition or making fishing weights
  • making stained glass
  • refinishing furniture
  • artists paints that contain lead
  • lead solder for electronics
• occupational sources such as factories, industry and repair:
  • secondary metal smelters
  • brass or copper foundries
  • automobile repair shops
  • industrial machinery and equipment
  • remodeling or renovating old homes
  • chemical and chemical preparations
  • bridge, tunnel and highway construction

References

1. Pirkle, J.L. , D.J. Brody, E.W. Gunter, R.A. Kramer, D.C. Paschal, K.M. Flegal, T.D. Matte. 1994. The decline in blood-lead levels in the United States. Journal of the American Medical Association. 272(July 27):284-291.
2. Nriagu, J.O. 1990. The rise and fall of leaded gasoline. The Science of the Total Environment. 92:13-28.
3. Montaque, P. 1997. Bad decisions again and again. Rachel's Environmental Health Weekly. #541(April 10). http://www.monitor.net.rachel.
4. Mielke, H. W., M.D. Taylor, C.R. Gonzales, M.K. Smith, P.V. Daniels and A.V. Bucknerl. Lead based hair products: Too hazardous for household use. Journal of American Pharmaceutical Association. NS37(Jan/Feb):85-89.
5. Citation for graph

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http://www.tmc.tulane.edu/ecme/leadhome/sources.html