Environmental Public Health Tracking: Lead Poisoning Data

Lead is a naturally occurring metal. It may be found by itself or with other minerals. Lead has no nutritional value, but it is useful in manufacturing. When lead enters the body, it is toxic and at high enough levels, it can cause lead poisoning.

Lead was used in house paint until it was banned in 1978. Daily activities that create friction, such as raising and lowering painted windows or climbing porch stairs, causing an impact on painted floors and stairs, can cause lead based paint (LBP) to break down into lead-contaminated dust. Lead dust can also be created when LBP is disturbed through home renovation or repair. That dust is mostly invisible and can be ingested by a young child unknowingly.

Lead is common in industries including construction, mining, and manufacturing, where workers are at risk of being exposed to lead by breathing it in, ingesting it, or coming in contact with it. People may also come into contact with lead through other jobs and hobbies. Lead poisoning can occur when working near lead dust, lead-based products, and lead fumes. Lead dust can also be taken home on workers’ clothing, shoes, or tools, which can expose children and other household members to lead (this is called “take-home lead”).

There is no safe level of lead in the human body. Even very low levels of exposure can cause adverse health effects.

Lead poisoning is commonly determined by measuring the amount of lead in a person’s body by using a blood test. The results are measured in micrograms per deciliter (µg/dL). Wisconsin statute (Wis. Stat. § 254.11[9]) defines lead poisoning in a child as a blood lead level of 5 or more µg/dL. The CDC (Centers for Disease Control and Prevention) in 2022 updated their definition to include blood lead levels of 3.5 or more µg/dL. However, there is no safe blood lead level; even very low levels of lead exposure can cause permanent brain damage and negatively affect learning, behavior, and health throughout a child’s life. Parents who would like to have their child tested for lead poisoning should contact their doctor or the local health department. CDC recommends a blood lead level of less than 3.5 µg/dL for adults as well.

This fact sheet (PDF) provides more information about the health effects of childhood lead poisoning. Visit the Prevention and Intervention for Lead Exposure webpage for more information on childhood lead poisoning.

Wisconsin Tracking tracks lead poisoning because it is a preventable threat to adults and children. By tracking the patterns for lead poisoning, professionals can better target their resources for the best prevention strategies.

Banning lead in gasoline, paint, and other products has helped reduce how much lead we come in contact with.

Children are more likely to get lead poisoning than adults. The CDC identifies lead as the number one environmental health threat to young children. Lead poisoning in children is preventable.

Prevention efforts are focused on children younger than 6 years old because:

• Their growing bodies absorb more lead than adults.
• Their brains and nervous systems are more sensitive to the damaging effects of lead. At this age, the brain is still developing, and lead poisoning can stunt this development.
• Children crawl and put objects in their mouths. They can come into contact with any lead that is present in their environment, such as lead dust on toys or on the floor.

Tracking childhood lead poisoning will help identify:

• Lead testing and poisoning rate changes over time
• Seasonal variations
• Geographic differences
• Differences in lead testing and poisoning by age, gender, and race/ethnicity
• Populations in need of targeted interventions

The website provides data from the Adult Lead Program and the Wisconsin Childhood Lead Poisoning Prevention Program at the Wisconsin Department of Health Services.

Adult lead

• Number and rate of all adults with blood lead levels at or over 3.5, 5, 10, 25, and 40 µg/dL
• Number and rate of adults newly recorded for the year with blood lead levels at or over 3.5, 5, 10, 25, and 40 µg/dL

Rates are adults per 100,000 employed adults in the state or county. All measures are available at the state and county level.

Childhood lead poisoning

• Number of children under 6 tested for lead poisoning
• Number of children under 6 testing positive for lead poisoning (in other words, number of children poisoned)
• Percent of children under 6 poisoned by lead among those who were tested for lead

All measures are available at the state, county, and census tract level on this map. 

For more boundary and map-mark options (lead contractors, municipal boundaries, local health department boundaries, and congressional districts) you can use the Childhood Lead Data Explorer map.

• The data collected are based on the number of children or adults tested and not based on all children or adults living in the state or local community.
• Data users should keep in mind that many factors contribute to a disease. These factors should be considered when interpreting the data. Factors include:
  • Demographics (race, gender, age)
  • Socioeconomic status (income level, education)
  • Geography (rural, urban)
  • Changes in the medical field (diagnosis patterns, reporting requirements)
  • Individual behavior (diet, smoking)

• Wisconsin Department of Health Services - Lead-Safe Wisconsin
• Wisconsin Department of Health Services - Adult Lead Program
• Wisconsin Department of Health Services - Children and the Environment
• Wisconsin Department of Health Services – Lead and Your Health, P-01738 (PDF)
• Wisconsin Department of Health Services - Take-Home Lead, P-01737
• Wisconsin Department of Natural Resources - Lead in Drinking Water (PDF)

Click the link below to download the data you're looking for:

Census Tract Data (CSV)

County Data (CSV)

State Data (CSV)

Number of children tested positive for childhood lead poisoning

Wisconsin blood lead testing data from children less than six years of age are reported to the Wisconsin Childhood Lead Poisoning Prevention Program. Lead poisoning is defined as a child with a capillary or venous blood lead level (BLL) greater than or equal to 3.5 micrograms per deciliter (μg/dL). This threshold was most recently updated by CDC in 2022. Prior to 2022, lead poisoning was defined as a child with a BLL greater than or equal to 5.0 ug/dL.

Data are de-duplicated within a given year such that they contain the most recent confirmatory (venous) test following an elevated screening (capillary) test. If no confirmatory test for the individual is available, the most recent screening test result is used. If a child had five tests in 2005, for example, only one test would be counted and reflected in the portal data. However, a child could appear in multiple time periods. For example, if I child was tested in 2005 at age three, the child could be retested in 2006 at age four. Both tests would be counted and reflected in the portal. The code "NPT" is used to indicate a poisoning case where the child was not previously tested and "PT" is used to indicate poisoning cases where the child was previously tested.

The number of children poisoned is a count value and is not the best manner to use for comparisons between counties or regions such as census tract. Some areas of the state will have higher numbers of poisonings simply because there are more people there. The percent of children poisoned is a better measure for comparison between geographic areas. To protect confidentiality, data are suppressed for census tracts or counties if fewer than five children are poisoned. However, those data are not suppressed if 100 or more children are tested. When viewing data downloaded from the portal, note that suppression is indicated by a value of -5. The Census tract refers to the child’s home address, not the place where the child was tested.

Number of children tested for childhood lead poisoning

Wisconsin blood lead testing data from children less than six years of age are reported to the Wisconsin Childhood Lead Poisoning Prevention Program. This measure is a count of all children tested. Children may be tested using a capillary or venous BLL with preference given to the latter when available. Children who received multiple tests are only counted once per year. To protect confidentiality, data are suppressed for census tracts or counties if fewer than five children are poisoned. However, those data are not suppressed if 100 or more children are tested. When viewing data downloaded from the portal, note that suppression is indicated by a value of -5.

Percent of children with childhood lead poisoning (among those tested)

Wisconsin blood lead testing data from children less than six years of age are reported to the Wisconsin Childhood Lead Poisoning Prevention Program.

Lead poisoning is defined as a child with a capillary or venous BLL greater than or equal to 3.5 micrograms per deciliter (μg/dL). This threshold was most recently updated by CDC in 2022. Prior to 2022, lead poisoning was defined as a child with a BLL greater than or equal to 5.0 ug/dL. Data are de-duplicated such that they contain the most recent confirmatory (venous) test following an elevated screening (capillary) test. If no confirmatory test for the individual is available, the most recent screening test result is used. The code "NPT" is used to indicate a poisoning case where the child was not previously tested and "PT" is used to indicate poisoning cases where the child was previously tested.

The percent of children poisoned is calculated as the number of children poisoned divided by the number of children tested. This measure is the most accurate one to use for comparisons between geographic areas of the state as it accounts, to a large degree, for differences in population size between regions. Note that the overall statewide age-specific percentage of poisoned children provided for reference may be greater than the sum of the percentages of poisoned children across all counties due to a small subset of blood lead test results missing county of residence information. 

To protect confidentiality, data are suppressed for census tracts or counties if fewer than five children are poisoned. However, those data are not suppressed if 100 or more children are tested. When viewing data downloaded from the portal, note that suppression is indicated by a value of -5.