By Amy Norton
health day reporter
TUESDAY, Aug. 16, 2022 (HealthDay News) — It is well known that lead exposure can harm the brain development of young children. Now, a new study suggests that racial segregation could worsen the harmful effects of lead on black children.
The study, involving nearly 26,000 schoolchildren, found that black children with high blood lead levels performed worse on standardized reading tests. And that effect was compounded when they also lived in highly racially segregated neighborhoods.
The specific reasons for the findings are unclear, the researchers said. But neighborhood segregation has deep roots in history, where practices such as “redlining” isolated many black Americans in areas with high poverty rates and little or no investment.
“Residential segregation is not an accident,” said lead author Mercedes Bravo, assistant research professor at the Duke Global Health Institute in Durham, North Carolina. “It’s the result of many years of structural racism that has separated people into different neighborhoods.”
Lack of investment in predominantly black neighborhoods has always meant fewer businesses, fewer job opportunities, poorer housing, and difficulty accessing basics from groceries to health care.
The new findings suggest that these factors may “interact” with lead exposure to worsen reading performance in black children, according to Bravo.
Lead is a natural metal that can have serious health effects if it accumulates in the blood. Children under the age of 6 are especially vulnerable because lead can damage their developing brains and cause learning or behavior problems.
Lead was once widely used in household paints and gasoline. Although these practices were phased out decades ago in the United States, there are still many ways children can be exposed, according to the US Centers for Disease Control and Prevention.
Children living in homes built before 1978 – when lead-based paint was banned – may be at risk if that old paint is still in place and is peeling or peeling.
Children can also be exposed by playing in lead-contaminated soil — near highways, factories, or airports, for example — or by drinking water that runs through lead pipes.
All of this means that black children living in poverty are at increased risk of being exposed to lead. A study last year found that 58% of children in predominantly black neighborhoods had detectable levels of lead in their blood, compared to 49% of children in predominantly white neighborhoods.
“That’s what makes this new study so important,” said David Cwiertny, director of the Center for Health Effects of Environmental Contamination at the University of Iowa. “These are children who are already more vulnerable to lead exposure.”
If other factors in their environment “aggravate” the effects of lead, that’s concerning, said Cwiertny, who was not part of the new research.
There is no “safe” blood lead level in children, Cwiertny said. But the CDC considers a level of 3.5 micrograms per deciliter (mcg/dL) to be higher than normal.
The current study, published August 15 in the Proceedings of the National Academy of Sciences ,involved 25,699 North Carolina children whose blood lead levels had been tested at some point. They all took standardized reading and math tests in fourth grade.
The Bravo team found that when black children had relatively lower lead levels (1–3 mcg/dL), neighborhood segregation had no impact on their reading test scores. But among black children with higher lead levels (4 mcg/dL or more), those living in highly segregated neighborhoods performed worse in reading. And the higher the children’s lead levels, the greater the impact of neighborhood segregation.
Bravo noted that the bigger picture isn’t entirely bleak: Children today are exposed to less lead than their counterparts decades ago.
But, she said, “the lasting legacy of structural racism” means that black children are at greater risk of lead and other environmental hazards and stressors.
“It’s not acceptable,” Bravo said.
“We haven’t done enough to reduce the sources of lead exposure,” he said. Leaded gasoline, for example, is still used in aviation because no alternative has been developed. And the lead service lines (underground water pipes) put in place at the start of the 20th century remain in many towns and communities.
The United States Environmental Protection Agency has estimated that there are between 6 and 10 million lead service lines nationwide. Federal funding is available to help states and utilities replace them.
But, Cwiertny said, local authorities often don’t even know where their main service lines are.
The United States Centers for Disease Control and Prevention has more on lead exposure.
SOURCES: Mercedes Bravo, PhD, assistant research professor, Duke Global Health Institute, Duke University, Durham, NC; David Cwiertny, PhD, professor, civil and environmental engineering, and director, Center for Health Effects of Environmental Contamination, University of Iowa, Iowa City; Proceedings of the National Academy of Sciences,August 15, 2022