Children’s health was front and center during the latest Early-Stage Investigator Spotlight Webinar, which was hosted by the NIEHS Environmental Health Sciences Core Centers Program on August 10. Angelico Mendy, M.D., Ph.D., discussed how replacement flame retardants affect children’s respiratory health, and Shelly Buffington, Ph.D., shared links between diet-induced obesity in pregnant women and neurodevelopmental disorders in children.

Mendy, an assistant professor of environmental and public health sciences at the University of Cincinnati, is affiliated with the university’s Center for Environmental Genetics (CEG). Buffington, an assistant professor at the University of Texas Medical Branch, is affiliated with Baylor College of Medicine’s Gulf Coast Center for Precision Environmental Health (GC-PEH). Both CEG and GC-PEH are part of the Core Centers Program.

The webinar was the seventh in a series that began in January and that has highlighted topics such as computational toxicology, sailors’ mental health during the pandemic, air pollution, and autism spectrum disorder, to name just a few.

Flame retardants and respiratory health

For many years, U.S. companies manufactured and imported flame retardants known as polybrominated diphenyl ethers (PBDEs) to reduce the risk of fire, putting them in electronics, furniture, mattresses, and car seats, according to Mendy. They were also used in infant products such as toys and sleep positioners. The substances can leach into the environment and accumulate in house dust, where people may breathe them in, and some of the chemicals can cross the placental barrier. Researchers began to link PBDEs to neurodevelopmental disorders in children, and that knowledge led companies to phase out the chemicals in 2004, he noted.

Businesses replaced those PBDEs with organophosphorus flame retardants and replacement brominated flame retardants. But researchers do not yet know the health effects of breathing in these substitutes, explained Mendy.

“There are a lot of gaps in the literature concerning the association between replacement flame retardants and respiratory health,” he told webinar attendees.

Mendy hypothesized that early-life exposure to organophosphorus flame retardants alone or in mixtures would be associated with adverse respiratory outcomes, which could be influenced by changes in gene expression. He used data from the Health Outcomes and Measures of the Environment Study, a pregnancy and birth cohort that included 400 women recruited in the greater Cincinnati metropolitan area between 2003 and 2006.

Exposure to replacement flame retardants via dust was measured in children at age one year. To assess respiratory outcomes, Mendy evaluated surveys from participants who reported respiratory infection, hay fever, and allergies in their children at six-month intervals until they were five years old, and he also analyzed peak expiratory flow at age five.

Preliminary results indicate that greater concentration of organophosphorus flame retardants in dust at age one year was associated with more frequent subsequent respiratory symptoms until age five and lower peak expiratory flow at age five, he said. That provides initial evidence that exposure to organophosphorus flame retardants may lead to adverse respiratory outcomes, noted Mendy.

Maternal nutrition and brain development

Obesity rates have increased around the world in recent years, a shift Buffington considers a mental health challenge. She said that is because obesity can affect children genetically predisposed to neurodevelopmental disorders, including autism spectrum disorder.

There is an emerging hypothesis that in these individuals, “environmental factors could be a tipping point for disease manifestation,” noted Buffington.

During her postdoctoral training, she created a model to observe the social behaviors of mice born to mothers fed a high-fat diet and those who were not. She observed significant deficits and lower interaction time in offspring of mice fed a high-fat diet. The interactions the young mice did have were low-quality and did not last long.

“We saw clear autism-like social dysfunction in our animals and really wanted to understand the underlying mechanism,” said Buffington. So, she created an experiment to look at microbiota in the maternal gut. Her results show that replacing certain bacterium in the guts of the mice with a probiotic could help to improve social behavior in their offspring.

“Just like we saw with the investigation into folate as a potential for rescuing neural tube defects in the 1960s, perhaps we are now able to look at maternal female probiotics as a way to decrease neurodevelopmental disorders,” she said.

(Susan Cosier is a contract writer for the NIEHS Office of Communications and Public Liaison.)