Definitions

Blood Lead Level (BLL):
The concentration of lead in blood, measured in micrograms per deciliter (mcg/dL).
Test:
Any blood lead level (BLL) sample (capillary, venous or unknown sample type) drawn that produces a quantifiable result and is analyzed by a Clinical Laboratory Improvement Amendments (CLIA) certified laboratory or an approved CLIA-waived portable device. A blood lead test may be conducted for screening purposes, as a confirmatory test or as a follow-up test.
Screening test:
A blood lead test for a child with no previous record of a confirmed elevated blood lead level. A child may be screened in multiple years and/or multiple times within a given year, but would be counted only once within each age category.
Birth Year Cohort:
Children born in a given year in a specified jurisdiction. Birth year cohorts are used as the denominator for calculating screening rates because they are the most accurate estimate of the population of children in a given age group who would require a screening test.
Birth Cohort Screening Rate:
Number of children born in a specified birth year who receive screening tests in specified age groups and geographic areas, divided by the total number of children in the birth cohort for the same geographic areas.
At or Around Age One:
Age range from nine months to less than eighteen months of age. This definition was established for surveillance purposes based on an analysis of age at which children received blood lead screening tests between the years 1999 to 2005.
At or Around Age Two:
Age range from eighteen months to less than thirty-six months of age. This definition was established for surveillance purposes based on an analysis of age at which children received blood lead screening tests between the years 1999 to 2005.
Elevated Blood Lead Level (EBLL):
Blood lead concentrations ≥ 10 mcg/dL. This is the blood lead level currently defined by the federal Centers for Disease Control and Prevention (CDC) as the level requiring public health intervention.
Confirmed EBLL:
One venous blood specimen ≥ 10 mcg/dL or any combination of two capillary and/or unknown type blood specimens ≥ 10 mcg/dL drawn within 12 weeks of each other.
Incidence:
The total number of children who are identified for the first time with confirmed EBLLs within a specified time period.
Incidence rate:
The total number of children identified for the first time with confirmed EBLLs in a specified time period, divided by the total number of children that had screening tests in that same time period, multiplied by 1,000.
Prevalence:
The total number of children with EBLLs in a given year, including both children who have newly confirmed EBLLs and those who had previously confirmed EBLLs and continue to have EBLLs at follow up testing during the year assessed.
Prevalence Rate:
The total number of children with confirmed EBLLs in a given time period, divided by the total number of children tested in that time period (including screening, confirmation, and follow-up tests), multiplied by 1,000. For children with more than one test in a given year, the single highest BLL was retained for analysis.
Natural Breaks Method:
A statistical method which groups data values into categories that optimize both the similarity of values within each category and the differences in values between categories. The resulting data range categories represent real clusters with separate data range categories dividing the clusters. Data range categories on the map figures were guided by the natural breaks method when producing the thematic maps using Pitney Bowes MapInfo software.