CDC National Childhood Blood Lead Surveillance Data
CDC’s childhood blood lead surveillance system at the national-level integrates information collected by state and local health departments. State and local childhood lead poisoning prevention programs supported by cooperative agreements are required to provide childhood blood lead surveillance data to CDC; other programs may provide data on a voluntary basis.
CDC applies nationally consistent standard definitions and classifications for blood lead surveillance data from all states. In addition, CDC applies rigorous error-checking and validation algorithms to the data submitted to ensure only one test per individual per year is counted. Therefore, the information available from CDC will not match data reports from the individual states because states may use different case definitions for clinical and environmental management.
About 4 million blood lead test results are received by CDC each year. These reports are processed, validated, and any submission errors are reconciled with the state before being analyzed and grouped into a reportable surveillance format. Once CDC receives the data, careful cleaning and deduplication ensure only one test per individual is counted in any given year.
The National Surveillance Data tableexcel icon in Excel excel icon[XLS – 57 KB] or PDF pdf icon[PDF – 474 KB] shows state-level blood lead test data summarized by state, year, and blood lead level (BLL) group. This table represents data reported by state to the national surveillance system over the past several years (2012-2017). The data represents only a subset of state-specific data and is not a population-based estimate, so we are not able to compare states or generate national prevalence estimates.
Limitations of the Data
The childhood blood lead surveillance data on CDC’s website are not a population-based estimate; NHANES is the best available source for nationally-representative, population-based prevalence estimates of elevated blood lead levels in U.S. children. The blood lead surveillance data are not representative of the U.S. or even of an entire state or county. Not all children are at risk for lead exposure and, therefore, not all children need to receive a blood lead test. CDC recommends that states develop statewide blood lead screening plans based on local data and conditions pdf icon[PDF – 1 MB]. However, blood lead testing is initiated by health care providers and it is difficult to know why or how health care providers decide to test children for lead. Programs are designed to target resources to the highest-risk areas and work diligently to understand the completeness and representativeness of their state-based blood lead surveillance data. Nonetheless, these data are collected for the purposes of program management and cannot be accurately compared between states or between counties within a state. Percentages of children with elevated blood lead levels can be affected by
- Population size (denominator data)
- Number of children tested (within a geographical unit)
- Type of children tested (low vs. high risk)
- Screening recommendations (targeted or universal)
Some statistics could underestimate the number of children with lead exposure because not all children are tested. For example, children who receive Medicaid assistance are required to receive a blood lead test at 12 and 24 months age (or between 36 and 72 months if earlier tests are missed)external icon as part of early periodic screening requirements; however, not all Medicaid-enrolled children receive the required blood lead testsexternal icon. These children are also at the highest risk of being exposed to lead.