Prenatal exposure to flame retardants may increase the risk of reading problems in young children, according to a new study at Columbia University Vagelos College of Physicians and Surgeons in New York.
Approximately 2 million children have a learning disorder; of these, around 80% have a reading disorder. Genetics account for many, but not all, instances of reading disorders.
The research team hypothesized that in utero exposure to polybrominated diphenyl ethers (PBDEs) — a type of flame retardant known to have harmful effects on brain development — might alter the brain mechanisms involved in reading.
Although use of PBDEs has been banned, exposure to the compounds is still widespread because they do not degrade easily in the environment.
For the study, the researchers analyzed neuro-imaging data from 33 children (age 5), all beginning readers, who were first given a reading assessment to identify reading problems. They also used maternal blood samples, taken during pregnancy, to estimate prenatal exposure to PDBEs.
The results show that kids with a better-functioning reading network had fewer reading problems. They also showed that children with greater exposure to PDBEs had a less efficient reading network.
The researchers also looked to see if PDBE exposure affected the functioning of a different social-processing brain network previously linked to psychiatric disorders such as autism spectrum disorder. They found no such link.
“Since social processing problems are not a common aspect of reading disorders, our findings suggest that exposure to PDBEs doesn’t affect the whole brain, just the regions associated with reading,” said Amy Margolis, Ph.D., assistant professor of medical psychology in the Department of Psychiatry at Columbia University Vagelos College of Physicians and Surgeons.
Although exposure to PDBEs affected reading network function in the 5-year-olds, it did not have an impact on word recognition in this group. The finding is consistent with a previous study, in which the effects of exposure to the compounds on reading were seen in older children but not in emergent readers.
“Our findings suggest that the effects of exposure are present in the brain before we can detect changes in behavior,” says Margolis. “Future studies should examine whether behavioral interventions at early ages can reduce the impact of these exposures on later emerging reading problems.”
The paper is published in the journal Environmental International.