We have known for quite some time that the first years of life represent a unique “window of vulnerability”—exposures to environmental chemicals at this time influence cellular programming in ways that shape health and disease in later years.
For example, recent research shows that there is a significant association between multiple prenatal and early life exposures to indoor pollutants and the degree of allergic sensitivity in 2-year old children. In other words, babies exposed to air pollution during prenatal life and for the first several moths after birth, up to 2 years of age, are at higher risk of developing allergic sensitivity.
Now, results from a study published on February 18, 2021, show that children exposed to polluted air may develop heart disease and other conditions in adulthood. Researchers measured three types of air pollutants: fine particulate matter known as PM2.5, carbon monoxide and ozone. PM2.5 comes out of the tail pipes of cars and trucks, and is also contained in wildfire smoke.
The researchers studied a cohort of school-aged children (6–8 years) living in Fresno, California—the city is known for its elevated levels of air pollution resulting partially from industrial agricultural practices and wildfires. A New York Times article from last November clearly points out the gravity of the situation in that area: “The fires sweeping across millions of acres in California aren’t just incinerating trees and houses. They’re also filling the lungs of California’s children with smoke, with potentially grave effects over the course of their lives.”
Study lead author Mary Prunicki said: “I think this is compelling enough for a pediatrician to say that we have evidence air pollution causes changes in the immune and cardiovascular system associated not only with asthma and respiratory diseases, as has been shown before. It looks like even brief air pollution exposure can actually change the regulation and expression of children’s genes and perhaps alter blood pressure, potentially laying the foundation for increased risk of disease later in life.”
The researchers assessed the effects of exposure to pollutants on the immune and cardiovascular systems. Specifically, they assessed methylation and protein expression in different cell types of the immune system using a form of mass spectrometry that measured up to 40 cell markers simultaneously, thus providing a more in-depth analysis of the impacts of pollution exposure. They also studied cardiovascular outcomes by determining blood pressure levels.
Study results show that over time exposure to pollutants is linked to increased methylation in cells of the immune system, an alteration that can change the activity of DNA molecules without changing their sequence and can have long term effects. Furthermore, air pollution exposure may influence monocytes, white blood cells that play a key role in the buildup of plaques in arteries—and could possibly predispose children to heart disease in adulthood. Thus, even at a young age, the immune and cardiovascular systems could be negatively impacted by exposure to air pollution.
Kari Nadeau, study senior author, said: “This is everyone’s problem. Nearly half of Americans and the vast majority of people around the world live in places with unhealthy air. Understanding and mitigating the impacts could save a lot of lives.”