Despite increased attention on childhood lead poisoning since the water crisis in Flint, Michigan, most efforts to describe the scope of the problem only focus on the children who have been tested for lead. However, no one has described how many children are not even being tested. Results of new research from the California Environmental Health Tracking Program show that many children may be falling through the cracks. Learn more below and in About the Methods.
Lead poisoning is preventable
Lead poisoning and its public health impacts are completely preventable. However, lead-based paint and lead dust remain in millions of older homes in the United States and continue to harm the developing brains of children. Other sources of lead include lead pipes, contaminated soil, and consumer products. While we should not wait until children are poisoned to find and remove hazardous lead from the environment, identifying all lead-exposed children (children with lead in their bodies) is essential to addressing this issue. Our research suggests that, for much of the country, current lead testing practices fall short of that goal.
An incomplete picture of lead poisoning
Commonly cited estimates of lead poisoning in children are based on results of blood tests conducted by medical providers. These estimates are incomplete because lead testing is not required for all children in the U.S., testing guidelines vary by state, and not all states report lead testing data. To assess the scope of the problem, the California Environmental Health Tracking Program (CEHTP), a program of the Public Health Institute, developed a statistical model using data from the National Health and Nutrition Examination Survey (NHANES) to estimate the actual number of lead-exposed children across the U.S. by state.
How many children are falling through the cracks?
To better understand how many lead-poisoned children may have been missed, we compared our estimates of the true number of lead-poisoned children with the numbers of children diagnosed with lead poisoning and reported to the Centers for Disease Control and Prevention (CDC) from 1999-2010. For this particular analysis, lead poisoning was defined as having a blood lead level of 10 ug/dL or higher among children 1-5 years old.
We estimated that 1.2 million children had lead poisoning from 1999-2010. In states that reported data to the CDC during this time, there were 944,000 lead-poisoned children, of whom only 607,000 were identified and reported.
This suggests that:
- Nationally, only 64% of lead-poisoned children were identified
- In California, only 37% of lead-poisoned children were identified
- Many states missed more than half of their lead-poisoned children
Our results indicate that:
- Lead poisoning in children is a problem throughout the country
- Estimates of child lead poisoning based on medical testing data are too low
- Current child lead testing practices are not effective in many states
Frequently Asked Questions
Many commonly cited estimates are based on the number of lead-exposed children identified by pediatricians and other medical providers through lead testing. But, some pediatricians test their patients thoroughly, while others do not test at all. So, for maps generated from lead testing data, it is difficult to know whether the "hot spots" are places where lead exposure is high or where pediatricians are doing a lot of tests. Therefore, lead testing data are of limited utility for understanding the extent of child lead poisoning across all states in the U.S.
In our research, we aimed to generate estimates of lead poisoning that could be comparable across the country and would be not be influenced by variations in medical lead testing practices. By using data from NHANES- a scientifically-rigorous national survey that collects blood lead data in a standardized manner and is representative of the entire U.S. population- we were able to generalize about lead exposure patterns throughout the U.S. and infer the numbers of lead-exposed children in each state.
Absent efforts to develop direct estimates by testing the blood of large numbers of randomly-selected children in each state, our methods represent the best approach for estimating the number of lead-exposed children in individual states, and our estimates will remain the best information available.
After 2010, due to changes in the data collected by NHANES, medical lead testing data have become our sole source of information on how many children are exposed to lead in each state. Therefore, to understand how useful lead testing data are for generating estimates of lead exposure, we must assess the completeness and consistency of lead testing and reporting.
Data suggest that there have not been widespread improvements in lead testing by medical providers since 2010. In 2015, only 38% of children 1-2 years old continuously enrolled in Medicaid had a lead test, despite legal requirements for these children to be tested. This suggests that under-testing continues to be an issue.
While blood lead levels in U.S. children have been reduced since the removal of lead from paint and gasoline, lead continues to present a danger to children. No level of lead in the body is safe, and harmful impacts occur at even the lowest measureable exposures to lead. High levels of lead can damage one's kidneys, nervous system, and other major organs, and can lead to seizures or death. Even low levels of lead can decrease cognitive functioning and IQ, are associated with behavioral problems, and have been shown to reduce a child's school performance, educational attainment, and future earning potential.
When children are not tested, their families are also less likely to receive the information and assistance needed to remove lead from the child's environment. Toxic lead will continue to persist in the environment and put future generations of children at risk until mitigation measures are taken, such as the removal of lead-based paint from homes.
In addition to lasting health effects, lead poisoning has been estimated to cost over $50 billion nationally each year due to decreased cognitive functioning and lost lifetime productivity. In California, lead costs an estimated $8-11 billion for all children born in a single year.
Our findings suggest that medical providers in many states should increase blood lead testing of children. While strategies for improving testing practices will vary by state, our results broadly demonstrate that medical providers must take lead poisoning more seriously as an urgent public health issue. Lead continues to be a widespread threat to children, and medical and public health practitioners should not drop their guard against its grave impacts.
Blood lead testing is a critical activity and should be part of a comprehensive strategy to prevent further exposure in children already found to be lead-exposed, identify and remove lead from our environment, and prevent lead exposure in future generations. Our results don't tell us if children who were diagnosed with lead exposure received follow-up testing, medical services, or support to identify and remove the lead hazards in their environment. The responses to blood tests showing lead exposure vary by state.
Childhood lead poisoning has long been recognized as a social justice issue, and some populations of children are at higher risk than others. Based on our analysis of NHANES data, we found that:
- African American and Hispanic children are more likely to have lead in their bodies than other children, regardless of the age of their home or family income.
- African American children are the most likely to be have higher blood lead levels (10 ug/dL and above).
- Hispanic children, while the least likely to have higher lead levels, are most likely to have lead exposure at lower levels (2.5 ug/dL and above). There is no safe level of lead in the body.
- Children living in poverty are more likely to have lead in their bodies than other children, regardless of their race/ethnicity or the age of their home. We used the U.S. Census Bureau definition of poverty for our study.
- Children living in older homes are more likely to have lead in their bodies than other children, regardless of their race/ethnicity or family income. For our study, older homes were defined as those built before the 1978 ban on lead paint in the U.S.
- Our findings are consistent with previous research that has found that African American children, children living in poverty, and children living in housing built before 1978 have higher levels of lead in their blood.
In the past, childhood lead poisoning has often been viewed as a problem confined to the Northeast and Midwest. Contrary to this perception, our research suggests that lead poisoning impacts children in all regions of the United States. Based on our research, we estimate that:
- The Northeast and Midwest regions identified the highest number of lead-exposed children
- The South had the highest number of children with lead exposure, yet identified only 25% of them.
- The West had the fewest number of lead-exposed children, but performed the worst at identification, with only 22% of lead-exposed children identified.
Since states with lower rates of lead-exposed children may still have hotspots, we recommend viewing our state Public Use Microdata Area (PUMA) maps to learn more.