National Health and Nutrition Examination Survey (NHANES)
Blood Lead Levels in the U.S. Population
The National Health and Nutrition Examination Survey (NHANES) is a population-based program of studies designed to assess the health and nutritional status of adults and children in the United States. NHANES is conducted by CDC’s National Center for Health Statistics (NCHS) on a sample of the U.S. population of all ages to reflect the nation overall, rather than individual states or counties. Beginning in 1960, and as a continuous survey since 1999, NHANES has examined a sample of about 5,000 persons across the country with 15 selected counties visited each year. The sampling plan follows a complex, stratified, multistage, probability-cluster design to select a nationally representative sample of the U.S. civilian, non-institutionalized population based on age, sex, and race/ethnicity. Data on a broad range of health topics are collected through personal household interviews, physical examinations, and laboratory tests.
Since 1976, as part of NHANES, blood lead levels in the U.S. population are measured by CDC’s National Center for Environmental Health (NCEH) Division of Laboratory Sciences using state-of-the-art methods for sample collection, quality control, and analysis. Blood lead levels in the U.S. population overall, including children, have declined over time even in the most high-risk areas. This is due, in large part, to successful Federal policies and an intense coordinated effort of public health interventions aimed at reducing sources of lead in the environment. In 2012, CDC adopted the blood lead reference value to identify children with blood lead levels that are much higher than most U.S. children. The blood lead reference value is equal to the 97.5th percentile of the estimated blood lead distribution in children age 1-5 years old based on NHANES data.
This graph shows the overall trend in geometric mean blood lead levels in U.S. children age 1-5 years which has declined from 15 µg/dL in the late 1970’s to <1 µg/dL in the most recent 4-years of NHANES, representing a 94% decrease over time.