Lead is one of the elements in nature. It is usually found in combination with other elements to form different minerals. The mineral called galena is most often mined in this country to produce lead metal as we recognize it.
There are so many sources of lead in our environment. An individual can get lead poisoning from a variety of sources. Major sources of lead exposure include lead in paint, gasoline, water distribution systems, food, and lead used in hobby activities. Lead exposure attributable to automobile air emissions was a major exposure source prior to 1796. Between 1976 and 1990, lead used in gasoline declined by 99.8% in the United States, but not in some other countries where lead is permitted in gasoline: National Association of Physicians for the Environment (NAPE, 1993).
1
Lead poisoning is an environmental and public health hazard of global proportions. Children and adults in virtually every region of the world are being exposed to unsafe levels of lead in the environment. In fact, children are exposed to lead from different sources, such as paint, gasoline, and solder, and through different pathways such as air, food, water, dust and soil. It can be from a single high level exposure or the cumulative effect of repeated high or low level exposures. Once introduced into an environment, it can stay there in a dangerous form for a very long time. For example, a home that was contaminated with lead dust from a renovation may lead poison a child many years later.
On one hand, in the U.S., the major sources of lead exposure culpability have shifted from gasoline to paint and water distribution systems and fixtures. On the other hand, in Eastern Europe and many developing countries, the air pollution contribution of lead exposure remains high.
Although all U.S. children are exposed to some lead from food, air, dust, and soil, some children are exposed to high dose sources of lead, lead-based paint is the most widespread and dangerous high-dose source of lead exposure for preschool children.
Lead-based Paint
Throughout the 1940’s and 1950’s lead-based paint was in widespread use. It continued to be used in lower concentrations until the mid-1970’s.
2
The manufacture of paint containing high concentrations of lead for interior and exterior residential surfaces, toys, and furniture was banned in 1978 by the Consumer Product Safety Commission.
3
Although lead-containing paint was banned for residential use in the United States in 1978, residential paint on older buildings is the most frequent source of lead exposure in young children. It has properties that make it deal as a base for glazes, paints, solder, bullets, sinks and plumbing fixtures. Lead has been used to make petroleum products, glass panels, crafts, batteries, jewelry pencils, colored newsprints, etc.
4
However, with high lead content is estimated to be in 74 percent of all housing built before 1980.
5
Those housing units containing deteriorating lead-based are the major concern. Of even greater concern is these homes that have young children as occupants.
Lead paint exposure accounts for as much as 90% of childhood lead poisoning. While generally considered an inner city problem, it is, in fact, not so.
6
Lead paint not only directly poisons individuals, but contaminates soils and other surfaces which can also be the cause of poisoning.
Millions of tons of lead-based paints were applied to housing in this country before it was banned in the 1970’s. It was considered the highest quality paint because it did not crack or peel and kept its color well. Many federal and state regulations required use of paint in public housing and other buildings.
Lead from different sources such as from lead-paint, gasoline, and solder may enter the body through air, food, water, dust and soil. Lead-based paint is still available for industrial, military and marine use and occasionally ends up being used in homes. Paint with high content is estimated to be in 74 percent of all housing built before 1980.
7
Those housing units containing deteriorating lead-based paint on surfaces broken, sanded, or scraped, it breaks into tiny, sometimes invisible, pieces that children may swallow or inhale.
Pica, a craving for unnatural food, is one way children are exposed to lead when they eat tiny pieces of peeling or chipping lead-base paint. A child does not have to eat paint chips, however, to become poisoned. More commonly, children ingest dust and soil contaminated with lead from paint that reenter that flakes or chalks as it ages. Lead-contaminated house dust can settle on floors, walls, and furniture. Settled lead dust can reenter the air through cleaning, such as vacuuming or sweeping, or by movement of people throughout the house. Lead-contaminated house dust, ingested via normal repetitive hand-to-mouth activity, is now recognized as a major contributor to lead poisoning in children. Adults can also be exposed to lead in the same ways.
The risk of lead poisoning is related to both the presence and the condition of the paint. The risks of lead poisoning are greater when lead-paint has deteriorated or when lead-based paint (even intact paint) is located on surfaces accessible to children. Lead-based paint on interior and exterior windows is a major concern because it is abraded into dust by repeated opening and closing of the windows.
As many as 60% of all housing units in Massachusetts (up to 85% in urban areas) contain lead paint. This is approximately 1.2 million dwellings in Massachusetts alone.
8
Conditions such as deteriorating paint, dwellings undergoing interior or exterior uncontrolled renovation without proper precautions taken, lead paint in places where children visit, lead contaminated soils, and lead paint in common areas of apartments all can contribute to a child’s exposure to lead paint. Paints used in industry on equipment or in playgrounds or parks may still contain lead. But, a variety of other substances contribute to lead poisoning. The normal activity that children engage in by putting their hands, fingers, and other objects in their mouth transfer lead containing dust into their bodies. The above factors contribute to the fact that the number of children exposed to lead paint is greater than the number who live in housing that contains lead paint and any child may be subject to exposure to lead from paints.
Lead allowed in paint now is still potentially a problem because at all levels of exposure, lead poisoning causes severe adverse health effects in both children and adults, affecting their ability to learn and thrive, their productivity, and their global competitiveness (U.S. National Academy of Sciences, 1993).
Lead in Homes
Exposure of children can also be the result of lead in household dust while there are obvious sources of lead in homes, such as peeling and other non-intact lead paint, there are also some not so obvious sources as well. Dust in homes can contain lead from lead painted surfaces that rub against each other. Windows and doors are a large source of this type of lead dust. This dust has been danger to children who play in the dust and put things in their mouth. Other lead exposure can result from sources such as toys, furniture, and older linoleum. It may be found in tableware as diverse as: ceramic dishes, bean pots, crystal, pewter, brass and enamel metal-ware. certain types of glazed and pewter dinnerware, and lead paint decorated drinking glasses. The Food and Drug Administration (FDA) set strict limits for the lead content on products made or sold in the United States. China and lead crystal can leach dangerous amounts of lead into food.
9
Lead in Food
Exposure may result from individuals eating foods contaminated with lead. This lead can come from foods grown in soils with a high lead content. Lead compounds were also once used as insecticides for certain fruits and vegetables. Lead has also contaminated foods from improper canning procedures, cooking foods in cans with soldered seams, and serving foods in plates or containers that contain lead or have lead containing coatings on their surfaces. Occasional servings of food from these products are acceptable, food storage is unsafe. Food can also be contaminated with lead when it is grown in soil with a high lead content or when plants are sprayed with insecticides containing lead. It may be in the paint on your walls, or in the water. Lead can be found in some soldered canned goods from other countries. Some home remedies also contain lead compounds that can be the cause of lead poisoning. As many as 5% of children have high enough lead intake through water and food to cause health risks.
10
Lead in Soils
Lead in soils and dust in the environment has been, and will continue to be, a source of lead poisoning. The sources include flaking, chipping, or weathering paint: improper renovation of buildings and disposal of building materials; lead by the side of roads that has settled out from burned leaded gasoline; settled dust from industrial sources and lead around houses from lead paint that has been scraped off during the continuing repainting of the house.
Lead in Water
Drinking water can also have dangerously high levels of lead. As many as one in five Americans are exposed to dangerously high levels of lead in water. Lead rarely found in water at its source. The water becomes contaminated as it moves through the water distribution system. The lead can come from lead pipes or connectors; lead solder used to connect pipes and fumes; brass fixtures; and lead lined tanks in water coolers. The most serious problems come when the water is acidic. The acidic water will greatly increase the amount of lead that will leech from lead plumbing. In 1986, the federal government has made it illegal to use lead solder (greater than 2% lead in solder) or nine (9) waterlines.
11
Newer pipes may pose more of a hazard than older pipes. In older pipes, a mineral scale develops on the interior of the pipe, preventing the lead from leaching into the water. Newer pipes do not have this scale.
Components causing lead contamination include lead pipes, lead-based copper piping solders and brass fixtures.
Lead pipes
for conveying drinking water has been used for centuries because of its flexibility, durability and long life. Lead pipes are used in the United States, however, lead concentrations exceeding the regulation levels owing to lead pipe were reported in a number of cities.
Lead Solder
have been identified as a significance source of lead contamination.
Brass Faucet
fixtures have been identified as a major lead source in tap water. Levels of lead contamination found in natural raw waters, treatment plants or in distribution mains are typically low and rarely exceed drinking water regulations. However, high lead levels are usually found at consumer’s taps. Tap water can be contaminated by lead pipes, copper pipes with lead solder or bronze and brass faucets contaminating lead.
Contamination of lead in groundwater origin from the dissolution of lead from soil and earth crust. Lead particulate from the combustion of leaded gasoline, fossil and ore smelting can contaminate local surface water by surface runoff. . Lead itself has minor content in the earth crust. A widely distribution in of lead sedimentary rock and soils are reported an average lead content of 10 mg in 1 kg (10ppm) soil usually found in upper ground soil and lead in a range of 7 to 12.5 ppm is found in sedimentary rock.(U.S..EPA, 1987).
12
This means that lead generally present in a form of carbonates and hydroxide complex in soil. The solubility of lead control the lead dissolution into surrounding water. Strongly absorption by soil and complexion by humus can further limit the lead concentrations in surface waters and groundwater.
Children are more affected by the same amount of lead from these and other sources than adults. Foods such as baby formula may pose a significant lead poisoning hazard if lead contaminated water is used in its preparation. As many as 5% of children have high enough lead intake through water and foods to cause health risks.
13
Lead in the Air
Lead in the air has come from a variety of sources. One of the largest contributors has been from leaded gasoline. Millions of tons of lead were added to gas before use was limited by EPA regulations restricting the use of lead in gasoline. Much of this lead is still present in the environment as lead in soils and lead in dust. Aside from lead paints, lead is emitted into the air from industrial emissions. These industrial sources included smelters, refineries, incinerators, power plants, manufacturing operations, recycling efforts, and hundreds of other sources.