Children living near major roads are at a higher risk for developmental delays, according to a new study authored by a UC Merced assistant professor and other researchers.
It’s likely caused by traffic-related pollutants, although the study didn’t measure the source of air pollution, said Sandie Ha, assistant professor of epidemiology at UC Merced and the lead author of the study published in the journal Environmental Research.
The study shows young children living close to major roads are twice as likely to score lower on tests of communications skills, and children born to women exposed to higher levels of traffic-related pollutants during pregnancy have a small but significantly higher likelihood of developmental delays during infancy and early childhood.
UC Merced recently announced the findings in a news release.
Ha and other researchers – including scientists from the National Institutes of Health, New York State Department of Health, and the University at Albany – analyzed data from 5,825 people involved in a New York Upstate KIDS Study. They matched those participants’ home, work, and day care addresses to roadway and Environmental Protection Agency data for estimating air pollution levels.
Ha said the study was conducted in New York because of funding limitations and to get results more quickly by utilizing existing data of 5,825 people involved in a previous study there. She hopes a similar study can be conducted in the central San Joaquin Valley.
Ha said upstate New York has relatively low air pollution levels compared to the Valley, so she expects Valley children living near major roads are at an even higher risk.
The study’s conclusion suggests that associations are present between developmental delays and air pollution “even at levels of exposure below current regulatory standards.”
Ha said that “these elevated risks, despite being modest, have strong public health implications for areas like the Central Valley where almost everyone is exposed to high levels of pollution.”
Researchers also said that early exposure to air pollutants may carry higher risk for developmental delays compared to similar exposures in the womb, and that exposure during childhood is more direct and doesn’t go through a pregnant woman’s defenses. Minimizing exposure to air pollution during pregnancy, infancy and early childhood – all key periods for brain development – is important.
Researchers said previous studies have linked exposure to common air pollutants in pregnancy to low birth weight, preterm birth and stillbirth, and that a few others found a higher risk of autism and lower cognitive functioning in children living near freeways.
Ha said more detailed research is needed, but the recent study is a good starting point. In response to a question about whether the developmental delays could have been caused by other factors related to poverty, Ha said researchers didn’t directly adjust the study for poverty, but they did account for maternal education, race and insurance status.
The study was funded by the National Institutes of Health and the UC Merced Senate Grant.