National Health and Nutrition Examination Survey

At a glance

The National Health and Nutrition Examination Survey (NHANES) is a population-based program of studies. It is designed to assess the health and nutritional status of adults and children in the United States.

Blood lead levels in the U.S. population

The updated Blood Lead, NHANES 2011-2018 table is available on CDC's National Exposure Report webpage.

Biomonitoring data from prior NHANES survey years can be found on the Biomonitoring Data Tables for Environmental Chemicals web page. The NHANES survey is designed to provide nationally representative information for the general U.S. population.

NHANES is conducted by CDC's National Center for Health Statistics (NCHS) on a sample of the U.S. population of all ages. This sample reflects the nation overall, rather than individual states or counties. The survey began in 1960 and has been continuous since 1999. NHANES has examined a sample of about 5,000 persons across the country with 15 selected counties visited each year.

Sampling plan

The sampling plan follows a complex, stratified, multistage, probability-cluster design. The sample includes 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.

Blood levels in the United States

Since 1976, CDC's National Center for Environmental Health (NCEH) Division of Laboratory Sciences has measured blood lead levels in the U.S.

Blood lead levels in U.S. population are measured by 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. It can also be attributed to an intense coordinated effort of public health interventions aimed at reducing sources of lead.

In 2012, CDC adopted the blood lead reference value based on NHANES data. This value helped 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 1-5 years.