Lead Based Paint
The poisonous properties of lead have been known since antiquity. Benjamin Franklin wrote of illness seen among typesetters and attributed it to their exposure to lead. Since lead is used in a wide variety of materials and products, it is dispersed throughout the environment and there are many opportunities for exposure and poisoning.
In recent years, more and more attention has been directed to "small" doses of lead, once thought harmless. As a result, lead was banned from house paint in 1978 and almost completely removed from gasoline. Nationwide health surveys conducted in the late 1970s and the late 1980s show dramatic decreases in blood-lead levels for all segments of the population. However, research also done in the '80s and '90s shows that serious damage can be done by blood-lead levels once thought harmless, without any obvious warning signs.
Young children are especially at risk for these health problems, which include delayed development, reading and learning difficulties, lowered IQ, hyperactivity, and discipline problems. It only requires a few grains of lead-contaminated dust, eaten (or inhaled) on a regular basis, to cause these problems. In some places, and in and around some homes, soil and house dust are contaminated with lead. Children's health can be impaired without parents even being aware.
It is estimated that three-quarters of the nation's houses built before 1978 have at least some lead-based paint, with those homes built before the 1950s likely to have high amounts. Properly managed, this paint poses little immediate risk. If allowed to deteriorate or if disturbed, however, lead from the paint or lead dust can cause serious hazards.
Sources of Lead Poisoning
Due to the widespread uses of lead in the past, there are numerous sources of lead in the environment. For most households, and for most children, the major source of lead is contaminated dust. The most important sources of lead contamination of dust are from old paint and from leaded gasoline (now banned for most uses). Near major traffic corridors, soils are sometimes heavily contaminated from the prior use of leaded gas. (As an element, lead does not decompose, and it tends to stay in place over the years.) If this soil is tracked into the house, it becomes an important health hazard.
Play areas with lead contamination can be an important source of exposure due to hand-to-mouth activity. Frequent hand-washing is especially important. Landscaping (grass, dense shrubs) can keep kids from coming in direct contact with contaminated soils. Soils of lands used as orchards in the 1940s may also be contaminated with lead (and arsenic) from pesticides used during that era.
Prior to 1950, paint contained as much as 50% lead. This percentage was reduced in later years, and lead paint was banned from residential use in 1978. Lead paint in good condition poses little risk, although friction surfaces (windows, doors, floors, and stairs) are a concern. Paint that is peeling or deteriorating is especially risky. As a general rule, the older the home, the greater the risk of lead paint. Occupants' poverty level and the house's disrepair are also strong predictors of a lead hazard. "Chewable surfaces" (e.g., child-accessible window sills, projecting moldings, painted knobs and handles, etc.) in homes with young children are also a concern if lead-based paint is present.
Some remodeling activities can produce heavy contamination if lead paint is involved. It is imperative that such work be done with an awareness of this possibility and with appropriate measures taken to control and contain lead paint chips and dust (a "good cleanup" may not be sufficient) to protect both workers and occupants. As of June 1999, contractors must provide occupants with a pamphlet on lead poisoning hazards if the work will disturb more than two square feet of paint in pre-1978 housing. We will talk more about lead paint and remodeling in the next overhead.
Water is another potential source of lead. Contaminated water usually occurs from lead in solder, fixtures, and piping in the home. Overall, the EPA estimates that about 10% of total lead intake is from water. Naturally soft water is more likely to leach lead from the home's plumbing than hard water.
Lead is a poison with no known useful function in the body. It can harm systems throughout the body in both adults and children. The most important health finding about lead in recent years is that even small doses, once thought harmless, can cause serious damage, especially in young children, without any evident symptoms.
In 1992, the Centers for Disease Control and Prevention substantially modified its earlier recommended "Intervention Level" for blood-lead. The previous standard of 25 micrograms per deciliter (mcg/dl) of blood was revised to recommend regular screening at 10 mcg/dl and monitoring and environmental investigation at 15-19 mcg/dl, with more forceful actions above this range.
As mentioned before, small doses of lead in children affect the developing nervous system causing delayed development, lowered IQ, reading and learning problems, hyperactivity, and discipline problems. Larger doses can affect adults as well as children and can cause problems such as high blood pressure, anemia, kidney trouble, and reproductive disorders. Convulsions and death can also occur, but these are rare.
Lead tends to accumulate in the body, and its harmful effects are mostly irreversible.
Lead and Children
Young children (up to about 6 years old) are especially at risk for lead exposure. There are several reasons for this. Frequent hand-to-mouth activity of young children provides an important path for ingestion of lead dust. Moreover, children's digestive tracts absorb a significant proportion of lead in comparison to adults. Perhaps most importantly, the period of rapid growth and development in the early years of life leaves the body's systems highly vulnerable to the effects of toxins.