CDC updates blood lead reference value to 3.5 µg/dL

CDC uses a blood lead reference value (BLRV) of 3.5 micrograms per deciliter (µg/dL) to identify children with blood lead levels that are higher than most children’s levels.

On October 28, 2021, CDC updated the blood lead reference value (BLRV) from 5.0 μg/dL to 3.5 μg/dL. A BLRV is intended to identify children with higher levels of lead in their blood compared with levels in most children. The value is based on the 97.5th percentile of the blood lead distribution in U.S. children ages 1–5 years. By updating the BLRV to 3.5 μg/dL, children with blood lead levels (BLLs) within the range of 3.5–5 μg/dL can now also receive prompt actions to mitigate health effects and remove or control exposure sources.

Updating the reference value encourages CDC, federal agencies, health departments, providers, communities, and other partners to take the following steps:

  • Focus resources on children with the highest levels of lead in their blood compared with levels in most children in that age range
  • Identify and eliminate sources of lead exposure
  • Take more prompt actions to reduce the harmful effects of lead

The BLRV is a population-based measurement that now indicates that 2.5% of U.S. children aged 1–5 years have BLLs at or above 3.5 μg/dL. It is not a health-based standard or a toxicity threshold. The BLRV should be used as a guide to 1) help determine whether medical or environmental follow-up are recommended and 2) prioritize communities with the most need for primary prevention of exposure.

Updating the BLRV supports CDC’s commitment to health equity and addressing environmental justice. The risk for lead exposure is not the same for all children. There are significant disparities in health outcomes across racial and ethnic groups and people with different socioeconomic status. Higher blood lead levels are more prevalent among children from racial and ethnic minority groups, children from low-income households, and children who live in housing built before 1978. Also, children from racial and ethnic minority groups are more likely to live in conditions where there is greater likelihood of exposure. Some of these conditions include poor housing and environmental exposures, such as lead in air, soil, and water.

CDC recommends that public health and clinical professionals focus screening efforts on neighborhoods and children at high risk, based on age of housing and socioeconomic risk factors:

  • Public health and clinical professionals should collaborate to develop screening plans responsive to local conditions, using local data.
  • In the absence of such plans, universal BLL testing is recommended.
  • Jurisdictions should follow the Centers for Medicare & Medicaid Services requirement that all Medicaid-enrolled children be tested at ages 12 months and 24 months or at age 2472 months if they have not previously been screened.

Protecting children from exposure to lead is important to lifelong good health. No safe BLL in children has been identified. Even low levels of lead in blood have been shown to reduce a child’s learning capacity, ability to pay attention, and academic achievement.

Some effects of exposure to lead can be permanent. If caught early, however, parents, healthcare providers, and communities can take actions to prevent further exposure and reduce damage to a child’s health. The most important step parents and caregivers, healthcare providers, and public health professionals can take is to prevent lead exposure before it occurs.

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