Lead paint

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Lead paint is paint containing lead, a heavy metal. Lead was added to paint as pigment and to speed drying, increase durability, retain a fresh appearance and resist moisture which caused corrosion. Because of its toxicity, paint containing more than 0.06% lead was banned for residential use in 1978 by the U.S. Consumer Product Safety Commission. Paint with significant lead content is still used in industry and by the military. For example, leaded paint is sometimes used to paint roadways and parking lot lines.

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[edit] History

For centuries, the primary white pigment in paints was white lead (basic lead carbonate, 2PbCO3·Pb(OH)2), one of the oldest pigments known. Red lead was once popular as a primer. Many countries banned lead in residential paint early in the 20th century. Despite mounting evidence of the effects of its use, lead was still used in paints in the United States until the danger became too widely known to be ignored. After the 1978 ban, paint manufacturers replaced lead with other ingredients, such as barium sulfate and titanium dioxide.

[edit] Toxicity

Although lead improved the performance of paint, lead is extremely toxic to living organisms. It is especially dangerous to children under age six whose bodies are still developing. Lead causes nervous system damage, hearing loss, stunted growth, reduced IQ, and delayed development. It can cause kidney damage. Lead affects every organ system of the body. It also is dangerous to adults, and can cause reproductive problems in adult men. One myth related to lead-based paint is that the most common cause of poisoning was eating leaded paint chips. In fact, the most common pathway of childhood lead exposure is through ingestion of lead dust through normal hand-to-mouth contact during which children swallow lead dust dislodged from deteriorated paint or leaded dust generated during remodeling or painting. Lead dust from remodeling or deteriorated paint lands on the floor near where children play and can ingest it. Some children were also exposed by chewing window sills or other componets painted with lead paint. This is because lead has a sweet taste and lead-poisoned children often suffer from a disease called pica, a craving to eat non-food items.

The U.S. Government defines "lead-based paint" as any "paint, surface coating that contains lead equal to or exceeding one milligram per square centimeter or 0.5% by weight." Some states have adopted this or similar definitions of "lead-based paint." These definitions are used to enforce regulations that apply to certain activities conducted in housing constructed prior to 1978, such as abatement, or the permanent elimination of a "lead-based paint hazard."

[edit] Lead-based paint in housing

Advertisement from the Lead Industry Association, November, 1940.
Enlarge
Advertisement from the Lead Industry Association, November, 1940.

One practical way to protect children from lead-based paint and prevent childhood lead poisoning is to keep old paint intact. Proper maintenance entails repainting before chipping or peeling occurs. Many children are poisoned during unsafe renovations or repainting jobs in pre-1978 housing. Therefore, carefully stabilize any deteriorated (peeling, chipping, cracking, etc.) paint in a lead-safe manner (see next paragraphs). Then simply repaint with new paint designed for household use.

Working in a lead-safe manner means avoiding dry sanding, dry scraping, removing paint by torching/burning, the use of heat guns over 1100 °F., machine-sanding or grinding without HEPA-filtered dust collection or HEPA-filtered vacuum. These methods are now prohibited by HUD because they have been proven to create significant levels of lead dust during remodeling, renovation and painting. They must be avoided, especially in properties where children under age six reside. Adult workers using unsafe work practices or improper protective gear may also become lead-poisoned.

Advertisement from the Lead Industry Association, November, 1940.
Enlarge
Advertisement from the Lead Industry Association, November, 1940.

The principles of lead safety during remodeling also include restricting access to the work area by not allowing children or pets to enter, laying thick plastic sheeting on the floor to collect dust, use of a filtered vacuum, wet washing surfaces to clean thoroughly at the conclusion of each day and the end of the job, and special attention to cleaning with repeat washing with detergent and vacuuming to pick up all remaining dust. In preparing the surface for painting, be aware that dry sanding or dry scraping may create undesirable lead dust, so spray a mist of water onto the surface to be prepped. This "wet sanding" and "wet scraping" methods creates much less dust than its dry counterparts.

HUD recommends a dust test for "clearance" at the end of any remodeling or repainting job be performed by a third-party professional who is independent of the entity performing the work. Contact your state's lead poisoning prevention program (call the local health department or environmental department) or look in your Yellow Pages director under "lead paint" or "environmental consultants" to locate a lead-based paint professional who can do a clearance examination for your job.

Lead laws: The Federal Government and many states have regulations regarding lead-based paint. Many of them apply to evaluating a property for lead-based paint (or lead hazards) and [abatement]. In addition, if a child is poisoned in a property, the owner may be required to make other permanent repairs or replace windows, for example, when the windows are shown to be hazardous because they generate lead dust from friction upon opening.

Lead evaluations are performed by laboratory analysis. Commercially-available lead test kits are often used to test for the presence of lead, but they are not completely reliable. The home's year of construction can be a clues as to the likelihood that lead is present in its paint. Homes older than 1940 almost certainly contain lead paint, homes built between 1960 and 1978 may contain lead paint, while homes built after 1978 are less likely to have lead-based paint. The U.S. Department of Housing and Urban Development's Office of Healthy Homes and Lead Hazard Control performs regular studies of housing-based health hazards in the U.S.

[edit] State action against the lead paint industry

The state of Rhode Island filed suit in 1999 to get the companies that used to sell lead-based paint to clean up the lead paint still contaminating many houses and apartments in Rhode Island. After one trial that ended in a hung jury, the state refilled the case.

In February 2006 the jury decided in favor of the state and said that Sherwin-Williams, NL Industries and Millennium Holdings would have to pay for a clean up of lead-paint in the state.

Earlier this year an appeals court in California reinstated a public nuisance lawsuit. A public nuisance lawsuit filed by the city of Milwaukee is scheduled to go to trial in 2007. There is a case now before the Supreme Court of New Jersey to determine if the case can go forward under the public-nuisance laws there. The case was originally filed in 2001 by twenty-six (26) public entities including the cities of Camden and Newark.

[edit] Lead disclosure in United States real estate transactions

In 1996, the Lead-Based Paint Disclosure Regulation was enacted. It requires owners of pre-1978 "target housing" to disclose to potential buyers or renters all known information about the presence of lead-based paint and/or lead-based paint hazards in the property. It requires that the potential buyer or tenant be given the lead information pamphlet, "Protect Your Family from Lead in Your Home," or other EPA-approved pamphlet as well as a specific disclosure statement.

[edit] Lead paint in art

In art, lead white is known as flake white, also sometimes known as Cremnitz white. Flake white is traditionally considered to be the most structurally sound underpainting layer for oil painting, possessing a combination of flexibility, toughness, and permanence that is not to be found in other paints, and certainly not in the other white pigments.[1] Genuine flake white is difficult for artists to obtain in many countries, even though other toxic paints (such as the cadmium-based colors) may be readily available. Where flake white is currently available to artists, it is usually only in small tubes designed for painting, not in the larger cans traditionally used for underpainting (coating the canvas prior to the actual painting) which was flake white's most important purpose.

[edit] Substitutes

Paint manufacturers replaced white lead with a less toxic substitute, titanium white (based on the pigment titanium dioxide) which was first used in paints in the 19th century. (In fact, titanium dioxide is considered safe enough to use as a food coloring and in toothpaste, and is a common ingredient in sunscreen.) The titanium white used in most paints today is often coated with silicon or aluminum oxides for better durability.

For artists, zinc white is less opaque than titanium white, and is better for misty glazes and adding aerial perspective.

Some art-supply manufacturers supply a "lead white hue," a mixture which attempts to imitate the hue of genuine lead paint without the toxicity. It does not, however, have the desirable structural (physical) properties of lead white.

[edit] References

  1. ^ For further discussion of this issue, see Ralph Mayer's classic work, The Artist's Handbook of Materials and Methods.

Rutherford J. Gettens; Hermann Kühn; W. T. Chase (1967). "Identification of the Materials of Paintings: Lead White". Studies in Conservation 12 (4): 125-139..

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