Air quality impacts early brain development

Study explores how living close to roadways may impact the brain

June 17, 2020

Science Daily/University of California - Davis

Researchers at the University of California, Davis, have found a link between traffic-related air pollution and an increased risk for changes in brain development relevant to neurodevelopmental disorders. Their study, based on rodent models, corroborates previous epidemiological evidence showing this association.

While air pollution has long been a concern for pulmonary and cardiovascular health, it has only been within the past decade that scientists have turned their attention to its effects on the brain, said UC Davis toxicologist Pamela Lein, senior author of the study, recently published in Translational Psychiatry.

Researchers had previously documented links between proximity to busy roadways and neurodevelopmental disorders such as autism, but preclinical data based on real-time exposures to traffic-related air pollution was scarce to nonexistent.

Lein worked with UC Davis atmospheric scientist Anthony Wexler and first author Kelley Patten, a doctoral student in the UC Davis graduate group for pharmacology and toxicology, to develop a novel approach to study the impacts of traffic-related air pollution in real time. They set up a vivarium near a traffic tunnel in Northern California so they could mimic, as closely as possible, the experience of humans in a rodent model.

"This approach was a creative way to get at the question of what impacts air pollution has on the brain in the absence of confounding factors such as socioeconomic influences, diet, etc.," Lein said. "It's important to know if living close to these roadways poses a significant risk to the developing human brain.

"If it does," Lein continues, "scientists can warn susceptible individuals, such as pregnant women -- particularly those who have already had a child diagnosed with a neurodevelopmental disorder -- to take appropriate precautions to minimize risks to the health of their child's brain."

EARLY EXPOSURE OUTCOMES 

The researchers compared the brains of rat pups exposed to traffic-related air pollution with those exposed to filtered air. Both air sources were drawn from the tunnel in real time.

They found abnormal growth and increased neuroinflammation in the brains of animals exposed to air pollution. This suggests that air pollution exposure during critical developmental periods may increase the risk for changes in the developing brain that are associated with neurodevelopmental disorders.

"What we witnessed are subtle changes," Patten said. "But we are seeing these effects using air pollution exposures that fall within regulatory limits. With the backdrop of other environmental and genetic risk factors in humans, this may have a more pronounced effect. This exposure also contains very fine particulate matter that isn't currently regulated."

In a separate study, Patten extended this exposure for 14 months to look at longer-term impacts of traffic-related air pollution and is in the process of writing up those results.

The team is also interested in what component of traffic-related air pollution is driving the neurodevelopmental outcomes.

If they can identify the culprits, Lein said, then scientists can approach legislators to develop scientifically based regulations to protect the developing human brain.

TEAM EFFORTS

UC Davis atmospheric scientist and co-author Keith Bein said that the single most challenging aspect of studying the health effects of air pollution may be replicating how, when and what people are exposed to throughout their lifetimes.

Tackling this requires creative thinking and a multidisciplinary team of researchers, including exposure engineers, atmospheric scientists, toxicologists, biologists, behaviorists and animal care specialists.

"We have managed to build a unique and talented team and taken advantage of our built environment to bring us closer than we've been before to achieving these objectives," Bein said. "Increasingly, these types of efforts are required to continue advancing the field, thereby informing policymakers and stakeholders about how best to protect human health."

Other study co-authors include: Eduardo González and Anthony Valenzuela, UC Davis School of Veterinary Medicine; Elizabeth Berg, UC Davis School of Medicine; Christopher Wallis, UC Davis Air Quality Research Center; Joel Garbrow, Washington University; and Jill Silverman at the UC Davis MIND Institute and School of Medicine. The study was supported by the National Institutes of Health.

https://www.sciencedaily.com/releases/2020/06/200617145934.htm

Household chemical use linked to child language delays

Children in low-income homes at risk, study finds

March 4, 2020

Science Daily/Ohio State University

Young children from low-income homes whose mothers reported frequent use of toxic chemicals such as household cleaners were more likely to show delays in language development by age 2, a new study found.

In addition, the children scored lower on a test of cognitive development. These developmental delays were evident even when the researchers took into account factors such as the education and income of mothers, which are also linked to their children's language and cognitive skills.

The findings provide additional evidence of the need for pediatricians and other health care providers to counsel parents of young children to restrict their use of toxic household chemicals, said Hui Jiang, lead author of the study and senior research associate at The Ohio State University.

"We found that a significant percentage of mothers with young children may commonly expose their children to toxic household chemicals, possibly because they are unaware that such materials may be harmful," said Jiang, who is with Ohio State's Crane Center for Early Childhood Research and Policy.

The study was published online recently in the journal Clinical Pediatrics.

The researchers used data on 190 families from the Kids in Columbus Study, a Crane Center research project that followed children born into low-income families in Columbus for five years after birth.

When they first started the study, mothers were asked about their use of household chemicals such as floor and toilet cleaners and solvents during pregnancy. They were asked again when their child was 14 to 23 months old. Mothers also reported whether they had mold in the home, their use of pesticides, and neighborhood pollution sources.

Children's language development was measured when they were between 14 and 23 months old and again when they were 20 to 25 months old. The researchers used a standardized test that examines children's understanding and expression of language -- for example, recognition of objects and people, following directions, and naming objects and pictures.

Findings showed that neighborhood pollution, mold in the house and pesticide use were not significantly linked to child outcomes.

But the more household chemicals mothers reported using regularly after childbirth, the lower the child language and cognitive outcomes at 2 years of age.

There was no link between chemical use during pregnancy and child outcomes, possibly because mothers reported using significantly fewer chemicals during pregnancy.

Exposure to toxic chemicals was reported by about 20 percent of mothers during pregnancy, but that increased to 30 percent when their children were between 1 and 2 years old. Mothers also reported using more household chemicals after childbirth.

"A lot of mothers seem to know to limit exposure to toxic chemicals during pregnancy, but once their child is born, they may think it is no longer a problem," Jiang said.

But research has shown these early years of a child's life are key in many ways, said Laura Justice, co-author of the study and professor of educational psychology at Ohio State.

"When kids reach about 2 years old, that is a peak time for brain development," said Justice, who is executive director of The Crane Center.

"If the use of toxic chemicals is interfering with that development, that could lead to problems with language and cognitive growth."

While many mothers may use household cleaners and other toxic chemicals when their children are young, low-income mothers may face particular challenges, Jiang said.

For example, they often live in smaller apartments where it may be more difficult to keep children away from chemicals, particularly while they are cleaning.

Jiang noted that this study simply analyzed the relationship between mothers' use of toxic chemicals and later child development and as such can't prove that chemical use caused the developmental delays.

"Future studies are need to more carefully examine the mechanisms through which household toxicants may disrupt early language development," she said.

The findings do show that pediatricians need to emphasize that pregnancy is not the only time for mothers to be concerned about chemical use, Justice said.

"Parents need to understand the delicacy of brain development in the first several years of life and their children's susceptibility to chemical exposure," she said.

https://www.sciencedaily.com/releases/2020/03/200304141534.htm