Health Effects of Exposure to Lead

Lead, a naturally occurring metal, has been used to produce gasoline, ceramic products, paints, and solder. In homes built before 1978, lead-based paint and lead-contaminated dust from paint are the primary sources of exposure to lead. Major initiatives have been implemented to reduce lead exposure by phasing lead out of gasoline, paint, solder, and plumbing fixtures.

Health problems from lead exposure are a major environmental health problem because exposure to lead is widespread and can cause health effects at relatively low levels. Substantial data are available to link lead exposure with health effects. Lead adversely affects the nervous system, can lower intelligence, and has been associated with behavioral and attention problems. It also affects the kidney and blood-forming organs.Children and the developing fetus are more vulnerable to the effects of lead than adults.

The level of lead in blood has long been used as an indicator of exposure to lead. And, because the linkage between lead exposure and health effects is so strong, blood lead is also used as an indicator of adverse effects on the nervous system.

In the 1970s, lead poisoning occurred increasingly in children who did not live in dwellings with lead-based paint, suggesting that another source or sources of lead exposure were of even greater concern than lead paint. Research found that combustion of leaded gasoline was the primary source of lead in the environment. In the 1970s, EPA promulgated regulations to ban lead in gasoline. Since that time, concentrations of lead in blood samples and in ambient air have declined significantly (Exhibit 4-7). In young children, the median concentration of lead in blood decreased by 85 percent from 1976 to 1999-2000 based on nationwide surveys.

But national averages of blood levels tell only part of the story. Between 1999 and 2000, approximately 430,000 children ages 1 to 5 (about 2 percent) had elevated blood lead levels (10 µg/dL or greater) from eating paint chips or inhaling lead-containing dust in older homes, primarily in urban areas. Even today, lead poisoning is considered to be a serious environmental hazard in young children in the U.S. Several major metropolitan areas, including Chicago, Detroit, Milwaukee, Palo Alto, and St. Louis, are evaluating blood lead levels of young children, focusing on areas at high risk (i.e., older housing and poorer neighborhoods), to study and address potential problems (see box, “Children’s Lead Levels Remain a Concern in Urban Hot Spots”). These blood lead screening programs, however, do not report in a systematic fashion to a central location where the data can be evaluated.