Genetic Factors Could Increase the Risk of Developmental Delays From Lead Exposure

Exposure to even low levels of lead during pregnancy may increase the risk of delayed cognitive skills and development in children with certain genetic traits, according to the findings of a new study.

In a report published this week in the medical journal JAMA Network Open, researchers indicate that children who were exposed to lead before birth were more likely to have difficulty learning language, social skills, and retaining memory at 2 years of age, compared to children who were not exposed to lead prenatally.

The findings revealed that prenatal lead exposure was associated with an increased risk of mental impairment in children, and those with genetic factors that predisposed them to developmental delays had an even higher chance of having poor cognitive abilities. Exposure to lead in the first 12 weeks of pregnancy was found to have the most pronounced effect on infant mental development, and female infants were more susceptible to lead toxicity than males.

Lead Exposure Adds to Genetic Developmental Risks

Lead (pb) is a toxic heavy metal that can cause a number of serious health issues for adults and children, including nervous system injuries, brain damage, seizures, convulsions, coma, cognitive impairment, and even death.

In recent years, health officials have established that there is no safe blood lead level for developing fetuses, and even exposure to small lead levels has been associated with poor or delayed mental development. However, researchers sought to investigate the link between prenatal lead exposure and genetic factors that may predispose them to cognitive developmental delays (CDD).

In this latest study, researchers from China analyzed the blood lead levels and cognitive DNA gene data of 2,361 pairs of mothers and children, including 1,240 boys and 1,121 girls born between March 2014 and December 2017, from the prenatal stage until the child reached approximately 2 years of age. The researchers sought to compare the instances of delayed cognitive developments among children who were exposed to lead before birth, with and without hereditary factors already known to be linked to mental development delays.

According to the findings, 292 children experienced cognitive developmental delays by the age of two, and all had some level of lead in their blood. Children had a significantly higher chance of having delayed mental function if their mother had higher levels of lead in their blood during pregnancy, and the risk of delayed development increased as lead blood concentration increased.

Those with a high genetic risk of developing a cognitive delay disorder had even higher instances of mental impairment, suggesting that prenatal lead exposure combined with cognitive delay genetic factors might alter the brain’s developmental response.

“In this cohort study, prenatal Pb exposure was associated with an increased risk of CDD in children, especially in those with a high genetic risk,” the researchers concluded. “These findings suggest that prenatal Pb exposure and genetic background may jointly contribute to an increased risk of CDD for children and indicate the possibility for an integrated strategy to assess CDD risk and improve children’s cognitive ability.”

Lead Health Concerns

Lead exposure and lead poisoning have been shown to have a substantial impact on children’s learning and developmental abilities, even after brief exposure.

The nonprofit organization Kids In Danger (KID) indicated in March that lead-related child product recalls were at the highest levels seen in the last decade, with 33 recalls were issued in 2022 over lead exposure hazards. Nineteen of the recalled products contained high levels of lead content, and eight involved children’s toys.

In April, the Environmental Protection Agency (EPA) indicated that approximately 9.2 million lead-tainted pipes are still part of the aging U.S. public water infrastructure and maintenance system, carrying contaminated drinking water homes and businesses and exposing large populations to lead of throughout the country.

Pediatrics published a study in September, finding that children living in racially segregated communities were more likely to have lead poisoning, and Black children were found to have higher levels of lead in their blood. Researchers have warned that children in impoverished areas have had an increased lead exposure risk since the 1990s through old houses, lead-based paint, and drinking water run through lead pipes.

Earlier this month, the EPA issued a statement warning of the threat leaded plane fuel poses to public health. The agency determined lead fuel used in certain planes can cause or contribute to air pollution, and result in child lead poisonings or premature adult deaths. Nearly 170,000 small-engine planes still use leaded fuel and continue to pose a public health risk, according to the EPA.