What is lead?
Lead, a toxic metal mined from the earth, has been used in many products for hundreds of years. Lead was removed from gasoline in the 1970s, but it can still be found in the soil, especially near roadways. Leaded paint was banned from sales to consumers in 1978, but it can still be found in many older houses, especially those built before 1960 and those in low-income neighborhoods and in poor repair. Lead can be found in some water pipes installed before 1986, and water can also be contaminated by lead solder previously used in pipes and with use of brass faucets and fixtures. Lead emissions from car battery or electronics recycling or other industrial sources can also contaminate soil and air. Lead can be found in a range of products, including aviation gas, wheel weights, industrial paints, fishing weights, bullets, car batteries, lubricants and toys, as well as in imported products often used in Latino and Asian communities such as folk remedies, cosmetics, contaminated foods and spices and lead-glazed cookware.
Over the past forty years, blood lead levels in American children have declined rapidly after the lead was removed from gasoline, paints, and other consumer products. Still, 1 in 50 preschool American children have lead poisoning (a total of about 535,000 U.S. children), which is defined as having a blood lead level above 5 micrograms per deciliter or 50 parts per billion. Lead exposure costs about $50 billion every year (Trasande, 2011).
How does lead gets into people’s bodies, especially for pregnant women and children?
Infants and toddlers are at higher risk for lead poisoning than older children and adults because infants and toddlers often put their hands and objects into their mouths, ingesting lead found in soil, house dust or flaking paint chips. Lead readily crosses the placenta during pregnancy. The developing fetus shares the mother’s exposures from using products containing lead, workplace exposures, or drinking lead-contaminated water. Women born outside the U.S. often have higher blood lead levels from exposures that occurred in their native countries.
What are the effects of lead on children’s brain development?
There is no safe level of lead in children’s blood. Blood lead levels < 5 μg/dL, which is 50 parts per billion, are associated with lower intelligence quotient (I.Q.) scores, learning deficits, developmental delay, school problems and school failure, attention deficits, and problem behaviors, like delinquency and conduct disorders. Children who have higher blood lead levels are more likely to have attention deficit hyperactivity disorder (ADHD), making them act impulsively, and become hyperactive and disorganized in their schoolwork.
Lead exposure has also has been associated with preterm birth and lower birth weight, which are risk factors for learning and developmental problems.