Agency for Toxic Substances and Disease Registry
Case Studies in Environmental Medicine (CSEM) 

Lead Toxicity
Where Is Lead Found?

Learning Objectives

Upon completion of this section, you will be able to

• describe potential sources of lead exposure in the U.S. today

Introduction

The distribution of lead in the environment varies from place to place. Each of the following sources of lead is discussed further below.

• The most widespread source of lead today for U.S. children is in lead paint that remains in older buildings.
• Lead may be found in and around workplaces that involve lead.
• Lead may contaminate water, food, and beverages, but the contaminant cannot be seen, tasted, or smelled.
• Lead may still be found in some commercial products.
• Some imported home remedies and cosmetics contain lead.
• Lead concentrations in soil, air, and water can be especially high near the sites of historic or ongoing mining operations or smelters.
• While blood lead levels over time are consistently declining, it is still a serious health problem for many, particularly children in urban areas.

Landrigan (2002) estimates that the U.S. incurs $43.4 billion annually in the costs of all pediatric environmental disease , with childhood lead poisoning alone accounting for the vast majority of it. This is a very high cost to our society, which include medical costs, disability, education and parental lost work time.

Homes and Buildings

Lead was banned from consumer use paint in the U.S. in 1977. Even though leaded paint may be covered with non-leaded paint, lead may still be released into the home environment by peeling, chipping, chalking, friction, or impact. Lead may also be released through past or ongoing home renovation. Lead-contaminated household dust is the major course of lead exposure to children in the U.S. (Lanphear et al. 2002)
Between 83% and 86% of all homes built before 1978 in the U.S. have lead-based paint in them. (CDC 1997a)

• The older the house, the more likely it is to contain lead-based paint and to have a higher concentration of lead in the paint.
• The number of existing U.S. housing units built before 1950, when paint had high lead content, decreased from 27.5 million in 1990 to 25.8 million in 2000 (CDC 2003); despite the gradual decline in the number of houses containing lead paint, however, it still poses a risk.
• Before 1955, a significant amount of white house paint sold and used was 50% lead and 50% linseed oil. In 1955, manufacturers adopted a voluntary house paint lead-content standard of 1%, but house paint with higher levels of lead continued to be manufactured. (Rabin 1989 as cited in AAP 1993)
• The amount of lead allowable in paint was lowered by federal law to 1% in 1971 and then to 0.06% in 1977.
• Workers renovating highway overpasses and bridges are frequently exposed to lead paint applied to these structures over many years before current regulations were in place.

In addition to degradation of interior paint, lead may be tracked into homes in significant quantities from exterior soil that was contaminated by historical use of lead in paint, gasoline, or industries.

Drinking Water

Lead occurs in drinking water through leaching from lead-containing pipes, faucets, and solder, which in turn can be found in plumbing of older buildings.

• Homes built before 1986 are more likely to have lead pipes, fixtures and solder, although newer homes may also be at risk.
• Boiling water will not get rid of lead.
• Other potential sources of lead contamination include brass fixtures, older drinking water coolers, and older coffee urns (Mushak et al. 1989 as cited in AAP 1993).

Foods and Beverages Contaminated with Lead

Even when lead is not intentionally used in a product, it may contaminate items such as food, water, or alcohol. Lead may contaminate food during

• production and processing
• packaging
• storage

Production

Production sources may include

• root vegetables uptake from soil
• atmospheric lead deposition into leafy vegetables (Mushak et al. 1989 as cited in AAP 1993)
• grinding or cutting equipment during processing

Packaging

Lead in packaging may contaminate food.

• Bright red and yellow paints on bread bags and candy may contain lead (ATSDR 2005; Mushak et al. 1989 as cited in AAP 1993).
• Although lead was phased out of cans in the U.S. in the 1980’s, some imported cans may still contain lead.

Storage

Food or beverages may be stored in lead-containing vessels that contaminate the product.

• Even "safe" pottery and ceramic-ware can become harmful if the protective glaze wears off and exposes people to lead-containing pigments.
• Lead-glazed pottery, particularly if it is imported, is a potential source of exposure that is often overlooked.
• Wine and homemade alcohol that was distilled and/or stored in leaded containers.
• Wine or other alcoholic drinks stored in leaded-crystal glassware may become contaminated.

Other

Other sources of food contamination include

• candies, especially chili-based imported from Mexico
• certain “natural” calcium supplements
• some ceramic tableware (especially imported)

Commercial Products

While lead is prohibited from many products in the U.S., imported or pre-regulation products may still pose a risk. Consumer products are not routinely tested for lead.

Lead is still used in commercial products such as

• automotive batteries
• bridge paint
• computers
• jewelry
• pewter
• some ceramic glazes

Imported Home Remedies and Cosmetics

Using certain imported home remedies or cosmetics. Several examples are listed below.

The Mexican folk remedies azarcon and greta used to treat the colic-like illness "empacho" contain lead. These remedies are also known as

• alarcon
• coral
• liga
• Maria Luisa
• rueda

Lead-containing remedies used by some Asian communities are

• ba-baw-san
• bali goli
• chuifong
• ghasard
• kandu
• tokuwan

Middle Eastern remedies and cosmetics include

• alkohl
• cebagin
• saoott

For more information on these products, see the Centers for Disease Control web site, especially Appendix 1 of the document “Managing Elevated Blood Lead Levels Among Young Children” (CDC 2002) at http://www.cdc.gov/nceh/lead/CaseManagement/caseManage_main.htm or Saper et al. 2004.

The Natural Environment

Because of widespread human use of lead, lead is ubiquitous in the environment. These background levels vary depending on historic and ongoing uses in the area.

• Even abandoned industrial lead sites, such as old mines or lead smelters, may continue to pose a potential public health hazard.
• Industrial sources range in size from large mines and hazardous waste sites (e.g., Superfund sites) to small garages working with old car batteries.
• Industries such as mining and lead smelting contribute to high levels of lead in the environment around such facilities.
• Local community members may be exposed to lead from these sources through ingestion (or inhalation) of lead-contaminated dust or soils.
• Old leaded paint may also contaminate soil, especially in areas immediately adjacent to pre-1978 houses.
• People may be exposed to lead in soils directly or by eating foods grown on lead-contaminated soils.
• The past use of lead in gasoline has contaminated soils, especially along roadways. Tetraethyl lead was phased out of gasoline in the U.S. between 1976 and 1996.

Workplaces

The major exposure pathways for workers are inhalation and ingestion of lead-bearing dust and fumes.
Workers in the lead smelting, refining, and manufacturing industries experience the highest and most prolonged occupational exposures to lead (ATSDR 2005).
Increased risk for occupational lead exposure occurs among

• battery manufacturing plants
• construction workers especially renovation/rehabilitation
• rubber products and plastics industries
• soldering
• steel welding/cutting operations
• other manufacturing industries (ATSDR 2005)
• bridge maintenance and repair workers
• municipal waste incinerator workers
• people who work with lead solder
• radiator repair mechanics
• pottery/ceramics industry employees

Primary Exposure

It is important to note that occupational exposures can also result in secondary exposure for workers’ families if workers bring home lead-contaminated dust on their skin, clothes, or shoes.

• Children may also be exposed to occupational lead sources if parents work in these industries and allow their children to visit them at work.
• Many small businesses and cottage industries are actually located in the home.

Secondary Exposure

Secondary exposures can be prevented by workers showering and/or changing clothing and shoes before returning home.

Lead solder/pipes

Drinking water

Packages or storage containers

Food, beverages

Paint (pre-1978)

Household dust and soil

Production sources

Imported foods, remedies, cosmetics, jewelry

Mining and smelting

Outdoor air and dust

Workplaces involving lead

Outdoor and indoor air and dust

Gasoline (pre-1988)

Soil

Key Points

• Prior to the 1970s, lead was widely used in paint and gasoline.
• Lead paint is a primary source of environmental exposure to lead. Lead may be released from old paint in home environments if the paint is disturbed (e.g., renovation), deteriorated (peeling, chipping, and chalking), or subject to friction or impact (doors, windows, porches, etc…).
• The past use of lead in gasoline and paint can result in high lead levels in soil.
• Some commercial products still contain lead.
• Workers in many industries (and secondary exposure to their families) may have occupational exposure to lead.
• Contaminated drinking water, food, alcohol, and home remedies are sources of environmental exposure to lead.
• Historic or ongoing lead-related industries (including mining and smelting) can result in high lead levels in surrounding soil.

Progress Check