Lead is usually mined and refined into its elemental form, which is a heavy bluish-white substance. Once mined, lead is often converted into other chemical forms, such as lead carbonate, the pigment used in paint. Yet once taken from the earth, lead will always be a potential health hazard. It is one of the navy metals, like mercury, that is considered hazardous to the human body. Despite this danger, lead’s color stability made it desired pigment to put into paint.
Paint consists of pigment (color), a resin or polymer (which forms a coating or film) and a solvent (in which the pigment and resins are suspended). When the paint is applied, the solvent evaporates, leaving behind the pigment. Pigment is the actual material, or “color,” left on the surface that has been painted. You may have noticed, when opening a can of paint, that the liquid has separated into its different components: solvent and resin float to the top, and pigment sinks to the bottom. The paint must be vigorously stirred or mixed before it can be used. In lead paint, the pigment is composed of various compounds which contain lead.
There are many forms of lead used in paint pigments; the two most common forms are white lead (basic lead carbonate) and red lead (one form of lead oxide). The amount of lead in the pigment is very high, often more than 38% of the dried weight of the paint. After the solvent dries, the dried paint contains pigment oils and resins that either coat or penetrate the treated surface. In this manner, the surface is protected from weathering or wear, and its useful life is extended.
No, because not all paints contain lead. Historically, lead paint was favored for use by both public and private consumers, due to its durability. In many cases, lead paint was specifically requested, even by architects and the federal government. Millions of tons of lead were incorporated into paint.
Once lead pigment was proven to be a health hazard, it was officially banned from paints used in residences. Regulations to this end went into effect in 1978. Before this date, however, other non-leaded paints, such as latex-based paints (which substitute titanium dioxide for lead carbonate), were also used on homes. Hence, it is not possible to tell for certain whether or not a surface contains lead paint by simply looking at it or scraping it.
The painted surface must be examined by a trained inspector. If the building was built before 1978, the possibility of lead- painted surfaces increases, in particular, the painted exterior surfaces and walls.
Lead paint has not yet been banned from use altogether. Its renowned durability makes it the pigment of choice for use on industrial surfaces, such as bridges and traffic lane markers.
Lead in our living areas and our food chain is due to an industrial environment, not to natural processes. Our bodies are not designed to process lead and therefore it is a poison. It has no biological use in the human body, even in trace amounts.
When introduced into the body by ingestion or inhalation, the lead pigments are separated and the body is fooled into accept- accepting them as normal, healthy elements like calcium and iron. The lead pigment then changes form and becomes an improper part of the body’s biochemistry, inhibiting the ability of various body organs to perform their normal function. Often cells die and are not replaced, and the entire body deteriorates.
It is not possible for the body to rid itself of all the lead that has entered it; lead will remain stored in the bones for decades beyond the initial exposure period. The total amount of lead stored in the body is often termed the “body burden”.
With exposure or re-exposure to lead paint/dust, the amount of this body burden can further increase; in so saying, the effect of exposure is cumulative. Hence a person may suffer initial exposure during childhood, which then may be compounded in adulthood by living in a contaminated residence, working in a hazardous environment, or by eating contaminated food.
Lead paint becomes harmful when inhaled as dust or ingested as paint chips. Of these two ways, dust is the less obvious, yet more common, mode of poisoning.
As our lead-painted architecture ages, the dust problem increases, as does lead exposure. The lead paint which previously covered wood surfaces is now wearing, flaking, and peeling off. The dust of this worn-off paint may be carried into the home by the wind, where it can become imbedded in fabric, in rugs or cracks in floors. Dust may also accumulate on window sills or other such exposed areas.
The dust is easily picked up by the touch of a hand or any object, especially those that are wet. Thus a toy wetted by a child’s mouth is capable of picking up contaminated dust, which is then ingested when the child puts the toy back in higher mouth. Paint chips are the most visible sign of lead paint problems.
Since lead paint is most deteriorated on the exterior of houses, the chips often find their way into window sills and the soil surrounding the building. Until recently, soil was ignored when investigators looked for evidence of lead poisoning; now, due to awareness that lead can enter the ground by means of paint deterioration and by auto emissions, soil is suspect for its possible contribution to lead poisoning. Lead can enter into the food chain by way of the soil and be unsuspectingly ingested.
THE RISK OF LEAD PAINT EXPOSURE
Most people do not realize the danger posed by the lead-based paint covering the walls and exterior of their homes. If the old flakes or the dust of such paint is ingested in sufficient amounts, it can cause lead poisoning, a condition that can lead to noticeable impairment of health, including brain damage and possibly death.
Until recently, soil was ignored when investigators looked for evidence of lead poisoning; now, due to awareness that lead can enter the ground by means of paint deterioration and by auto emissions, soil is suspect for its possible contribution to lead poisoning.
COMMON HAZARDS OF LEAD PAINT AND HOW THEY OCCUR
ADULT EXPOSURES TO LEAD PAINT
Adults can also be poisoned by accidentally ingesting lead paint, for example, by eating food contaminated by a paint chip. Other means of adult exposure include contamination by workers who bring lead dust home from their high-exposure work environment, and thereby expose their spouses and children. Workers with potentially high exposure to lead include lead smelter workers, as well as those removing lead paint from industrial and residential buildings (lead abatement workers).
WORKER EXPOSURES TO LEAD PAINT
Dust kicked up by one group of workers, such as the lead abatement workers, can inadvertently expose other workers, who in turn may bring their contaminated belongings home, and thus unknowingly expose their family to the lead poison. In the construction and decorating trades, workers may not realize that the surfaces being treated during the course of their work may contain lead. Nor do they realize that the generated dust is being incorporated into their air, clothing, and tools.
In one case, a steel river bridge was being repainted. Its surface was first “sandblasted” to remove the paint, rust, and any other material which would prevent the new coat of paint from adhering. The dust from the sandblasting contained large amounts of lead, which contaminated other construction workers on the site, as well as the river and nearby land.
Properly trained and certified lead abatement workers are well aware of these risks. They are careful to wear protective clothing, clean their tools, and erect barriers to avoid contaminating other workers on the site.
PAINTERS AND LEAD PAINT EFFECTS
Historically, painters have been innocent victims of lead paint poisoning. Lead from the dust of sanded surfaces and from the aerosol formed by paint was incorporated into their bodies in large doses. Over a long period of time, their “body burden” of lead was deposited into their bones. Yet these people did not realize they were suffering, because visible signs of toxicity would only occur on hot, sunny, summer days. On such occasions, they would exhibit classical symptoms of lead poisoning, which included lethargy, nausea, vomiting, and occasional seizures. The lead in their bodies had been mobilized by exposure to sunlight, which activated the vitamin D (calcium pathway of bone change), and also released large amounts of lead into their blood.
Do-it-yourselfers and their families are another large group of past and potential victims. When “rehabbing” older homes, which often contained large amounts of lead paint, the dust generated from sanding old paint contaminated their entire dwelling. In the 1970s and 1980s, many of the children of these do it-yourselfers were poisoned by exposure to this dust.
Dust remains a potential hazard today because many people are unaware that they can release dangerous lead- paint dust into the air while “rehabbing” property.
OTHERS AT RISK OF LEAD PAINT
Some medical disorders can make people highly susceptible to lead poisoning. Mentally impaired individuals are at risk, being more sensitive to smaller amounts of lead. As their brains are already working at maximum capacity, no reserve pathways exist to make up for further damage caused by lead poisoning.
In addition, individuals displaying the pica condition (a habitual hand to mouth action) tend to ingest more lead than healthy people, for their disease renders them apt to pick up contaminated dust and uncontrollably put it in their mouths.
PET EXPOSURES TO LEAD PAINT
Virtually everyone can be affected by lead paint, including pets, because lead paint has a sweet taste. President Bush’s dog, Millie, attracted national media attention by exhibiting symptoms of lead paint poisoning, presumably from chewing on the White House.
Children run the greatest risk of being lead poisoned because lead is easily incorporated into their growing bodies, where it disrupts the normal growth pattern of cells. Accumulation of smaller amounts of lead in a child’s body may also result in damage that does not become visible until the child is old enough to express learning disabilities. Studies have shown that as many as three million children may have been exposed to lead poisoning, and many of these have been adversely affected.
Young children are most often the victims of lead paint poisoning, since they put almost anything into their mouths, chewing on wood trim, window sills and other potential lead- painted surfaces. The single most widely exposed group appears to be young children living in older residences contaminated by lead paint. Studies have shown that this group suffers subtle neurological damage, caused by blood lead levels which were previously believed to be non-toxic.
The potential to cause harm to small children has prompted some states to take legislative action against this problem, resulting in regulations that force home owners, tenants, and landlords to carefully examine the paint covering their dwellings.
The unborn child is also susceptible to lead health hazards.
Even without direct contact to environmental lead, the unborn child can be poisoned. If a pregnant woman has been exposed to enough lead, her bones may store high levels of lead. The metabolic changes which occur in the body during pregnancy may cause the stored lead to be released into the blood, thus exposing the unborn child. Because the unborn child is extremely sensitive to any environmental toxins, the potential for damage is even greater than that of exposing a child or an adult to the same amount of lead.
Of particular concern is the developing neurological system of the developing unborn child. Studies have claimed that permanent learning disabilities can be attributed to exposure during this stage of development.