CDC investigation: Blood lead levels higher after switch to Flint River water

The Centers for Disease Control and Prevention (CDC) today released the results of its investigation into the potential health impact that lead contamination in the Flint, Michigan water supply had on the blood lead levels of local children.  The findings indicate that when the source of the water supply was switched to the Flint River, without appropriate corrosion control measures, young children who drank the water had blood lead levels (BLLs) that were significantly higher than when the source of water was the Detroit water system. After the switch back to the Detroit water system, the percentage of children under 6 years with elevated blood lead levels returned to levels seen before the water switch took place.

“This crisis was entirely preventable, and a startling reminder of the critical need to eliminate all sources of lead from our children’s environment,” said Patrick Breysse, Ph.D., director of CDC’s National Center for Environmental Health. “CDC is committed to continued support for the people of Flint through our Childhood Lead Poisoning Prevention program and efforts to raise awareness and promote action to address the critical public health issue in communities across the country.”

To understand the impact of consuming contaminated drinking water on children’s blood lead levels, CDC researchers examined data on levels of lead in blood of children younger than six years before, during, and after the switch in Flint’s water source. The current CDC blood lead level of concern (also known as a reference level) is 5 or more micrograms of lead per deciliter of blood (≥5 µg/dL). This reference value is based on the population of children ages 1-5 years in the U.S. who are in the top 2.5% of children tested for lead in their blood.

From April 25, 2014, to October 15, 2015 (the period when the Flint River was used for drinking water),  the levels of lead in Flint tap water increased over time and analysis of children’s blood lead data detected an increase in BLLs ≥5 µg/dL. The likelihood that a child consuming the water would have a blood lead level ≥5 µg/dL was nearly 50 percent higher after the switch to Flint River water. CDC continues to recommend that all children under age 6 living in the City of Flint have their blood tested for lead by a health care provider, particularly if they have not had a blood lead test since October 2015. All children with BLLs ≥5 µg/dL should receive evaluation and follow up, including a home assessment for sources of lead, and health and developmental assessments.

The CDC study had limitations. Researchers were not able to account for all of the factors that might have contributed to a child’s exposure to lead, including whether lead-based paint was present in the child’s living environment. In addition, researchers did not have information on the amount of lead in or the amount of water consumed by the tested children, limiting the analysis to evaluation of changes in blood lead levels over time as the source water changed.

Lead exposure remains a health concern for young children in the United States. Risk varies across the country, but because there are often no obvious symptoms, the exposure frequently goes unrecognized. Even low levels of lead in children’s blood have been shown to affect intelligence, ability to pay attention, and academic achievement.

“Parents and teachers can do a lot to help children grow up healthy and strong, even if they were exposed to lead,” said U.S. Department of Health and Human Services’ Assistant Secretary for Preparedness and Response Dr. Nicole Lurie, M.D., who is leading the federal response efforts in Flint. “We have followed up directly with the families in Flint whose children showed elevated levels of lead in their blood in an effort to ensure they are getting the additional assessments and case management services they need. We have also expanded Medicaid and strongly urge parents to enroll their children and schedule appointments for them to be seen by a health provider, who can follow their health as they grow and develop. It is also important to for families to take advantage of the  programs we have made available that offer healthy foods, and to get kids involved in programs that stimulate their brains – like Head Start and summer reading programs.”

CDC lead screening recommendations urge state and local health departments to review local data and develop recommendations for health-care providers that target at-risk children in their areas, focusing on children ages 1 to 2 years. Based on data in Michigan, public health authorities and health care providers recommend blood-lead testing for children living at or below the poverty level and children enrolled in Medicaid.

Flint residents are advised to use lead-certified water filters that are properly installed and maintained on their household taps and to use filtered water for drinking, cooking and brushing teeth. Regular household tap water can be used for bathing and showering because lead is not absorbed into the skin; however, parents should watch young children to prevent them from drinking bath water.

For more information about CDC’s Childhood Lead Poisoning Prevention Program, visit http://www.cdc.gov/nceh/lead/. For the full article, visit http://www.cdc.gov/mmwr/index.html.

For more about the Obama Administration’s efforts to help the people in Flint recover from the water crisis, visit https://www.whitehouse.gov/the-press-office/2016/05/03/fact-sheet-federal-support-flint-water-crisis-response-and-recovery.

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U.S. DEPARTMENT OF HEALTH AND HUMAN SERVICES