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Lead paint is paint containing lead, a heavy metal, that is used as pigment, with lead(II) chromate (PbCrO4, "chrome yellow") and lead(II) carbonate(PbCO3, "white lead") being the most common. Lead is also added to paint to speed drying, increase durability, retain a fresh appearance, and resist moisture which causes corrosion. 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.
Additional recommended knowledge
Although lead improves paint performance, it is a dangerous substance. It is especially damaging 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 and affects every organ system of the body. It also is dangerous to adults, and can cause reproductive problems for both men and women.
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.
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 not found in other paints, and certainly not in the other white pigments. 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.
Lead paint will often become discolored over long periods of time. This is due to the reaction of the lead carbonate in the paint with traces of hydrogen sulfide in the air and with acids, often from fingerprints.  As a result, many older works of art that used lead paint now show some discoloration.
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, usually of titanium and zinc white, 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.
Lead-based paint in the United States
Paint containing more than 0.06% (600 ppm)[vague] lead was banned for residential use in the United States in 1978 by the U.S. Consumer Product Safety Commission (16 Code of Federal Regulations CFR 1303). 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."
Lead-based paint in real estate maintenance and renovation
Proper maintenance entails repainting before chipping or peeling occurs. Many children are poisoned during unsafe renovations or repainting jobs in pre-1978 housing. Therefore, homeowners are encouraged to 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 the United States Department of Housing and Urban Development 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.
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 HEPA-filtered vacuum, wet washing surfaces (with a tri-sodium phosphate solution such as Ledi-Solv) 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. These "wet sanding" and "wet scraping" methods creates much less dust than its dry counterparts and is required by law.
Also, do not use methylene chloride, a common ingredient in paint strippers, to strip lead based paint. There are specialized paint strippers for use with lead paint such as LEAD-OUT Paint Stripper, Strip-Tox, Lead-X, and others. Some of these specialized strippers render lead non-hazardous decreasing the risks associated with lead paint removal.
HUD requires 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 U.S. Government and many states have regulations regarding lead-based paint. Many of them apply to evaluating a property for lead-based paint. There are two different testing procedures that are similar but yield different information. Lead-based paint inspections will evaluate all painted surfaces in a complex to determine where lead-based paint, if any, is present. The procedures for lead inspections is outlined in the HUD Guidelines, Chapter 7, 1997 Revision. The other testing is a lead-based paint risk assessment. In this testing, only deteriorated painted surfaces are tested and dust wipe samples are collected. This information will help the risk assessor determine if there are any lead hazards. Many property owners decided to get a combination of both tests to determine where are the property lead-based is present and what hazards are present as well. Risk assessments are outlined in the HUD Guidelines, Chapter 5. In addition, if a child is poisoned in a property, the owner may be required to perform abatement (permanent elimination of the lead hazard).
Lead evaluations of paint are usually performed by a field testing method known as X-Ray fluorescence (XRF) using equipment such as the RMD LPA-1 or the Thermo Scientific's Niton. XRF is the preferred method because it is not destructive and a reading is usually obtained in about 4-8 seconds with a 95% accuracy at the 2-sigma level. Instruments of this sort have an inconclusive range, and when a reading falls in this range (range is different for each instrument and model), a paint chip may be taken and sent for laboratory analysis. Testing for lead in dust, water, and air also require laboratory analysis. Commercially available lead test kits are often used to test for the presence of lead, but they are not reliable and not authorized by HUD to be used in determining if a property is lead-based paint free. 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.
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. Unfortunately, it allows owners to not even test for lead-based paint; instead owners can simply disclose that a test has never been performed.
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 refiled 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. The Missouri Supreme Court ruled against the City of St. Louis in their case against the lead paint companies in a 4-3 decision on 6/12/07 . They majority opinion cited Zafft v. Eli Lilly in saying that the city was unable to prove which company poisoned which children. 
Rutherford J. Gettens; Hermann Kühn; W. T. Chase (1967). "Identification of the Materials of Paintings: Lead White". Studies in Conservation 12 (4): 125-139..
|This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article "Lead_paint". A list of authors is available in Wikipedia.|