What is Lead Poisoning?

Smiling children sitting outside

What is Lead?

Lead is a naturally occurring element found in small amounts in the earth's crust. Lead was mined in Wisconsin. It was used in many products to stabilize things such as paint, varnish, gasoline, plastics, etc. However, lead is toxic to humans and animals. Using lead in products to which children and adults have ready access can cause lead poisoning.

What is Lead Poisoning?

Lead poisoning is an environmental disease that can cause brain damage. It can result in reduced IQ and attention span, learning disabilities, developmental delays, and a range of other health and behavioral effects. Lead poisoning is considered a housing-based disease because most exposures for young children occur in homes or child care centers built before 1978. In 1978, lead was banned from being added to paint and varnish for residential use. However because lead was added to paint, varnish and gasoline for many years, the lead is still present in the underlying layers of paint and varnish and in the soil.

How Does Lead Poison?

  • Chipping and peeling lead-based paint in older homes is ground to a very fine dust and is largely invisible. The lead dust may be in windows, on floors and porches and in the soil. When the lead-tainted dust gets on children’s hands and into their mouths they can become lead poisoned.
  • Another common way people get exposed to lead is when lead-based paint is being disturbed during renovation or remodeling. If the person doing the renovation is not working safely with the lead-based paint, the lead fumes and dust in the air can be inhaled or can be ingested by anyone in the area.
  • Other sources of lead exposure can include lead in drinking water service lines and fixtures; lead in soil from leaded gasoline, paint and industrial emissions; and lead in products such as toys, children's jewelry, candies, and traditional remedies, among others. 

How Can We Prevent Lead Poisoning?

Prevention of lead poisoning can be accomplished by eliminating lead hazards before children are exposed. Wisconsin's goal is to eliminate this disease by making Wisconsin's housing lead-safe, and by intervening early to stop the lead exposure before it can cause further harm to children.

Information on this page has been organized into three categories. Please choose one of the following tabs.

Lower Level Intervention

Previously, a child's blood lead level BLL ≥10 micrograms per deciliter (mcg/dL) was considered in need of intervention. In May 2012, the Centers for Disease Control and Prevention (CDC) concurred with its advisory committee's recommendation to lower that level to 5 mcg/dL. The recommendation was made due to overwhelming evidence that lead exposure at levels below 10 mcg/dL causes damage to the cognitive, cardiovascular, endocrine, and immune systems.

The advisory committee also recommended that CDC change its guidelines so that interventions previously identified for a BLL of 10 mcg/dL or greater go into effect at the new intervention level of 5 mcg/dL. CDC recommends the following interventions for a child with a BLL of 5 mcg/dL or greater:

  • Confirm a capillary blood lead test with a venous draw within 1 to 3 months.
  • Have child tested on the appropriate follow-up testing schedule.
  • Get a complete history and physical exam on the child.
  • Order the appropriate laboratory tests on the child such as tests for low iron or anemia.
  • Monitor the child's growth and development, especially as the child ages and enters school.
  • Provide education to the family on the sources of lead and how to reduce any lead hazards found.

This change significantly increased the number of Wisconsin children considered at risk for lead poisoning. More children being identified as having lead exposure earlier means that parents, doctors, public health officials, and communities can take action earlier. The advisory committee also said, as CDC has long said, that the best way to protect children is to prevent exposure in the first place. More information can be found in the advisory committee's report to CDC (PDF).

School Performance
and Behavior

Lead Affects School Performance and Behavior

Wisconsin Studies Show Lead Is Related to Poor Academic Performance and Suspension Activity

A study published by UW-Madison researchers on Milwaukee children (link is external) showed that students who had moderate exposure to lead before age 6 were at a considerable educational disadvantage compared to their unexposed peers seven to eight years later. Lead-exposed students in the fourth grade scored below fourth-grade ability, an outcome with serious negative consequences for both the student and the school.

A second study of Milwaukee students (link is external) showed that children with moderate lead exposure before the age of 3 were nearly three times more likely to be suspended in fourth grade compared to their peers who had little or no exposure to lead. This study showed that 23 percent of the education "achievement gap" between African American and white children was explained by early childhood lead exposure.

Studies Link Lead Exposure to Behavioral Problems

A recent study published in JAMA Pediatrics (link is external) showed that blood lead concentrations measured in more than 1,300 preschool children in China were associated with increased risk of behavioral and emotional problems, such as being anxious, depressed, or aggressive.

Another study on lead exposure and antisocial and risky behavior (link is external)was published in 2014 by the National Bureau of Economic Research. The author found higher exposure to lead in childhood is linked to major behavioral problems in later childhood and young adulthood, such as attention-deficit and hyperactivity disorder and teen pregnancy, as well as aggressive and criminal behavior.

Reading Readiness Affected by Lead Poisoning

Children attending a public kindergarten in Rhode Island were enrolled in a study of reading readiness at kindergarten entry (link is external). Reading readiness is an early measure of a child's capacity to integrate cognitive ability and skills learned from educational and enrichment experiences. Kindergarten is a critical time for identifying children with poor reading readiness and children with low lead exposure (5 to 9 mcg/dL) and high lead exposure (>= 10mcg/dL). Children with lead exposure of 5mcg/dL or greater showed a decrease in readiness scores compared to children with lead exposure levels below 5mcg/dL. The lead-exposed children scored 4.5 to 10 points lower.

Poor School Performance Found due to Lead Poisoning across U.S.

The National Center for Healthy Homes released a report on childhood lead exposure and educational outcomes (link is external). This issue brief highlights recent research on the dangers posed by low-level lead exposure and the resulting financial and social costs. Lead exposure occurs more frequently in low-income children and children of color and is an important factor in the educational achievement gap between children of different racial and income groups. Investing in the prevention of lead exposure and improved housing quality will yield improvements in educational outcomes. An At-a-Glance summary (link is external) of the report is also available.

Additional Resources

Report on Childhood Lead Poisoning in Wisconsin - 2014 (P-01202; PDF)

Lead Poisoning Education and Intervention: Tools and Resources for Community Awareness (P-00554; PDF)

Parents: Look Out for Lead (P-00660; PDF)

Your Child's Blood Lead Test Results (PDF) - National Center for Healthy Homes fact sheet and checklist for parents ¦ En Español (PDF)

Blood Lead Levels in Children (PDF) - Centers for Disease Control and Prevention fact sheet with guidance for health care providers when talking with parents about their child's blood lead level

Reliable Sources for More Information

U.S. Centers for Disease Control and Prevention - English ¦ En Español

U.S. Environmental Protection Agency - English ¦ En Español

U.S. Housing and Urban Development - English

Last Revised: June 30, 2017