≥3.5 µg/dL – This represents a measurement of greater than or equal to 3.5 micrograms of lead per deciliter of blood. The Health Department currently treats blood lead level tests of 3.5 µg/dL or more as elevated. This measurement is based on the Centers for Disease Control and Prevention’s definition, which was increased in 2021. Before that, the threshold was 5 µg/dL. Some documents with historical data still use that as a reference.
Capillary test – A capillary test is when blood is drawn by a finger-stick. The results are available within a couple of minutes. However, sometimes capillary tests can give incorrectly high results due to lead on the skin or in the environment. Because of this, a high capillary test should be confirmed by a venous test. A low/negative test does not require confirmation.
Venous test – A venous test is when blood is drawn from a vein in the arm. This is typically done to confirm a previous capillary test result and needs to be prescribed by a doctor. Some doctors will request a venous test without an initial capillary test.
Elevated capillary without follow up – If an initial capillary test was elevated but no venous test was done to confirm the result, it is considered an elevated capillary without follow up. The Health Department encourages providers to make sure follow up venous tests are performed in a timely manner.
Confirmed elevated blood lead level – The Health Department recognizes venous blood lead tests with a result of ≥3.5 µg/dL as a confirmed elevated case. Because one child may have received several tests, the highest venous test result is used as the final value.
Percent confirmed elevated (children with a confirmed elevated test / all children tested) - The percent of elevated blood lead levels that the Health Department follows is the number of individual children with confirmed elevated tests (only blood venous tests count as confirmed tests) divided by the number of individual children tested. For county-wide stratified data (3.5-4.9 µg/dL, 5 – 9.9 µg/dL, 10 + µg/dL), a child’s highest confirmed value is used. Measurements are not affected by multiple elevated blood tests for a single child in a single period.
Children (study population)– Lead surveillance is focused on children under age six years, in alignment with state and national surveillance standards. Lead is particularly toxic to the developing brain, and the hand-to-mouth habits of young children put them at increased risk of ingestion from contaminated sources.