Physician's Handbook on Childhood Lead Poisoning Prevention
Chapter Two
Environmental Sources of Lead
Summary
Children acquire lead from their environment principally through ingestion.
There are many potential sources and pathways of lead which may contribute to a particular child's lead exposure. These sources of lead are:
Interior and Exterior Paint
Children are poisoned by mouthing objects with lead dust on them, such as fingers and toys, by chewing on surfaces coated with lead paint, such as window sills, or by eating paint chips.
Soil and Dust
Over time, lead from a number of different sources has contaminated house dust, yards and playgrounds. In addition to lead-based paint, leaded gasoline and industrial sources have been implicated as sources of lead in soil and dust.
Drinking Water
The most likely sources of lead in drinking water are lead pipe, lead solder and brass fittings used in household plumbing.
Occupational Exposure
Construction, home renovation and steel and bridge workers in industries using lead may bring home lead dust on their clothes, skin and hair.
Hobbies
Hobbies, such as casting bullets and fishing weights, collecting lead toys or figurines, stripping and refinishing old wooden furniture and doors, and making stained glass and ceramic artwork, may be sources of domestic lead contamination.
Food
Lead enters the food chain from soil, deposition from the air, containers and food processing equipment.
Traditional Folk Remedies and Cosmetics
A number of remedies and cosmetics that contain lead have been identified.
Household Objects
A wide variety of household objects may contain lead, such as glassware, pottery, figurines, fishing weights, bullets, folk remedies and cosmetics. Other items containing lead which may be found in homes include curtain weights, plastic mini-blinds, antique toys and pewter.
Environmental Sources of Lead
Children acquire lead from environmental sources principally through ingestion. Lead is ingested directly as paint chips or following contamination of house dust, water and food. There are many potential sources of lead which may contribute to a particular child's lead exposure.
Interior and Exterior Paint
Ingestion of lead derived from lead-based paint is the most common modality of high-dose lead exposure for children. Children are poisoned by mouthing objects with lead dust on them, such as fingers and toys and by chewing on surfaces such as window sills which are coated with lead paint or by eating paint chips.
Dusting, flaking and peeling leaded paint is the most significant source of lead exposure in children. Even in well maintained housing units, some deterioration of paint occurs. As paint ages, it is converted into dust-sized particles. Children living in dilapidated older houses or well maintained houses undergoing renovation are at particular risk for lead poisoning due to contaminated house dust. Flaking exterior lead-based paint poses a similar threat to children playing in yards, playgrounds and even vacant lots where housing has been removed.
Remodeling of older homes containing leaded paint can disperse lead dust throughout the dwelling. This increases the likelihood of childhood lead poisoning through ingestion of that dust from fingers, contaminated food, dishware or eating utensils.
Since 1977, the Consumer Product Safety Commission has limited the lead in most paints to 0.06 percent (600 ppm by dry weight). Paint for bridges and marine use may contain greater amounts of lead.
Soil and Dust
Over time, lead from a number of different sources has contaminated house dust, yards and playgrounds. In addition to lead-based paint, leaded gasoline and industrial sources have been implicated as lead in soil and dust.
For many years, automobile exhaust from leaded gasoline was the single largest source of atmospheric lead. Although lead is no longer added to automobile gasolines, there is a substantially higher lead content in soil along highways and roads with high traffic flow. This may contribute to lead dust in nearby housing.
Industrial sources of lead include smelters, battery production or recycling, some paint and pigment production facilities and solid waste sites. Lead vapor and dust can be released in stack emissions from municipal incinerators. Lead may also be present in incinerator ash. Modern municipal waste-to-energy incinerators and permitted hazardous waste incinerators can release lead into the atmosphere. This occurs when air pollution control devices are not maintained or operated correctly.
Property formerly used for lead smelters, lead manufacturing, chemical waste management, auto salvage yards, waste oil recycling, municipal landfills and construction/demolition debris sites may contain lead. Contamination from these sites can result in human lead exposure via precipitation, infiltration, surface water runoff and air dispersion.
Drinking Water
Lead is more completely absorbed from drinking water than from food. Lead is not usually present in water at the source, but enters through the distribution system.
The most likely sources of lead in drinking water are lead pipes, lead solder and brass fittings used in household plumbing. It was common practice to use lead pipes for interior plumbing and for service connections joining residences to public water supplies before 1930. Copper pipes have been widely used since the 1930's and lead solder used to join copper pipes has been a source of contamination in household water. Lead was banned from solder in 1988. Brass used principally for valves is an alloy of copper and zinc with variable amounts of lead and other metals.
Corrosion, a chemical reaction that dissolves metal, can dissolve or leach lead from plumbing into drinking water. The corrosivity of water is affected by natural conditions and by water treatment. Water that is hot or that sits in pipes for extended periods, such as overnight, will likely contain more leached lead than cold water from a tap that has been run recently.
Acidic "soft" water (low mineral content of calcium and magnesium) may leach lead from plumbing, particularly when the water is hot.
Lead exposure from formula preparation has been described in infants. Common errors in preparation included; using first drawn morning water from a plumbing circuit with lead contamination, using "hot" tap water to prepare infant formula, extensively boiled tap water which, by evaporation, increases the lead concentration and lead vessels for boiling water.
Occupational Exposure
Chronic Lead Poisoning in Adults:
A blood lead concentration greater than 25 μg/dL is indicative of increased lead absorption in adults.
Parents working in construction, home renovations, steel and bridge work and other industries using lead may bring home lead dust on their clothes, shoes, skin and hair. Lead dust may contaminate their cars. Such occupations result in lead exposure to the adult and sometimes "take home" lead exposure to their children.
Lead paint is used on outdoor steel structures such as bridges, highways, boats and storage tanks. Workers engaged in maintenance activities such as grinding, cutting, drilling and debris clean-up are at serious risk of exposure and lead poisoning. Populations immediately downwind from these activities may be inadvertently exposed to lead dust if proper dust reduction and containment methods are not used.
Shooting ranges may be a source of exposure. There are over 400 shooting facilities in New York. Lead dust is produced from abrasion of bullets as they pass through the gun barrel and from fragments created when bullets strike the backstop. Lead residues remain on shell casings which are often collected for reloading. This lead may be brought home by the customer or range worker on clothing, skin and hair.
Occupations Associated with Lead Exposure:
- Lead production or smeltering
- Demolition of ships and bridges
- Production of illicit whiskey
- Battery manufacturing
- Brass, copper and lead (foundries)
- Matching and grinding lead alloys
- Radiator repair
- Welding of old painted metals
- Scrap handling of old buildings
- Thermal paint stripping of old buildings
- Sanding of old paint
- Ceramic glaze mixing
- Cable stripping
- Electronics welding
- Instructor or janitor at a firing range
Modified from Rempel D. (1989) "The Lead Exposed Worker" JAMA 262:533.
Hobbies
Hobbies such as casting bullets and fishing weights, collecting lead toys or figurines, stripping and refinishing old wooden furniture and doors and making stained glass, pottery or other artwork may create sources of domestic lead contamination.
Lead figurines are small statues cast primarily of lead with lesser amounts of tin and antimony. Figurines have been identified as a potential source of lead exposure in children. Large numbers of military and fantasy figurines, ranging in size from 2.5 to 13 centimeters, are sold each year in New York as collectibles or game pieces. They are sold at hobby shops, comic book stores, craft fairs and occasionally at toy stores. Most manufacturers include a warning on the package about potential lead exposure, but this is generally immediately discarded after purchase.
Although marketed principally to adults and school-age children, once in a home, lead figurines may become accessible to younger children who are already in the habit of playing with plastic figurines. During play, small children may ingest lead by mouthing, sucking or chewing on a figurine.
Food
Regulating lead contamination in foods is the responsibility of the United States Food and Drug Administration (FDA). The FDA has set a goal of less than 100 ug/day as the maximum lead intake by children one-to five years of age. Lead in food and beverages is encountered by virtually this entire age group in the United States. About 5 percent of children ingest enough lead from food and beverages to be at risk for adverse health effects. Lead enters the food chain from soil, deposition from the air, containers or dishes and from food processing equipment.
The FDA has estimated that about 20 percent of all dietary lead comes from canned food and two-thirds of that results from lead solder in cans. Acidic foods can leach lead from the solder in the seams of cans. The number of food cans that are lead-soldered continues to decline. In 1979, more than 90 percent of all food cans were lead soldered; in 1986, this figure was 20 percent or less than about two million cans. It is important to note that imported canned foods are not included in these figures and may still contain lead. Although the FDA has required the use of unleaded solder in baby food cans and has requested a phaseout of leaded solder in all food cans produced in the United States, some still remain on the market. The FDA phaseout does not apply to imported foods
Imported glazed ceramics and lead-containing pottery are also potential sources of dangerously high levels of lead. Lead glazed ceramics and lead crystal glassware can release lead into food and drink. Since ancient times, lead has been used in glazes for ceramic dishware. If lead glazed pottery is not fired to a high enough temperature for a long enough time, lead may subsequently be released from the glaze into food. Holding acidic foods and beverages such as tomato sauce, fruit juice, coffee, wine or vinegar, in inadequately fired ceramics, can leach this lead. Lead free glaze should be used on glazed ceramics.
Dishes and pottery made commercially in the United States since 1971 are generally safe to use. However, antiques and collectibles, dishes and pottery made in foreign countries and pieces made by amateurs for gifts or craft fairs may contain lead that could be a source of exposure if used for storing or serving food and drink.
Leaded crystal glassware may leach lead into food or beverages. The FDA recommend avoiding the use of leaded crystal glassware to store foods and beverages for extended periods of time.
Other sources of lead in food include urban gardens where the soil, air or water may be high in lead. Colored inks on plastic bread bags may contain lead pigments which leach into food when they are turned inside out for re-use. "Natural" calcium supplements derived from animal bone may contain lead if the animal source was exposed. Waterfowl may ingest leaded shot, become lead poisoned themselves and, possibly, be consumed by unsuspecting hunters and their families.
Traditional Folk Remedies and Cosmetics
A number of remedies and cosmetics that contain lead have been identified. The following are common folk remedies and cosmetics that contain lead:
Alkohl (also known as kohl, surma): a black powder used by Middle Eastern, African and Asian cultures as an eye cosmetic and umbilical stump remedy.
Azarcon (also known as reuda, liga, coral, alarcon and maria luise): a bright orange powder used by hispanic cultures to treat gastrointestinal upset and diarrhea.
Bali goli: a round, flat black bean which is dissolved in gripe water and used by Asian Indian cultures for stomach ache.
Ghazard: a brown powder used by Asian Indian cultures to aid digestion.
Household Objects
A wide variety of household objects may contain lead. Many already mentioned include glassware, ceramicware, figurines, fishing weights, bullets, folk remedies and cosmetics. Other lead-containing items that may be found in homes include plastic mini-blinds, curtain weights, imported crayons, antique toys, toy soldiers and pewter.
Bibliography
U.S. Environment Protection Agency (US EPA) (1987). Lead and Your Drinking Water, OPA-87-006.
New York State Department of Health (1992). A Preliminary Evaluation of Lead Exposure Associated with Lead Figurines.
Illinois Environmental Protection Agency. 1991.
Lead-Chemical Information Sheet. IEPA/ENV/91/209.
The National Rifle Association of America (1990). Effects of Exposure to Airborne Lead on Users of Indoor Firing Ranges. Second Edition.
New York State Department of Health (1992). Hazard Alert on Lead in Construction. Albany, NY: Author.
Olmez, I., J.P. Kotra, S. Lowery and W.H. Zoller (1984). Airborne Lead and Trace Elements in an indoor Shooting Range (1985). Environmental Toxicology and Chemistry, 4, 447-452.
U.S. Department of Labor (1991). Working with Lead in the Construction Industry. OSHA 3126
Food Chemical News (1991). Lead in Wine. 21.
Hawaii State Department of Health. Dishing Up Lead. A Guide to Poisonous Ceramics.
Lead Industries Association, Inc. (1972). Facts About Lead Glazes for Art Potters and Hobbyists.
U.S. Public Health Service, Agency for Toxic Substances and Disease Registry (1992). Case studies in Environmental Medicine. Atlanta, GA: Author.
U.S. Public Health Service, Agency for Toxic Substances and Disease Registry (1992). Toxicological Profile for Lead, Atlanta GA: Author.
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