Children exposed to air pollution, such as wildfire smoke and car exhaust, for
as little as one day may be doomed to higher rates of heart disease and other
ailments in adulthood, according to a new Stanford-led study. The analysis,
published in Nature Scientific Reports, is the first of its kind to
investigate air pollution's effects at the single cell level and to
simultaneously focus on both the cardiovascular and immune systems in
children. It confirms previous research that bad air can alter gene regulation
in a way that may impact long-term health -- a finding that could change the
way medical experts and parents think about the air children breathe, and
inform clinical interventions for those exposed to chronic elevated air
pollution.
"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," said study lead author Mary Prunicki, director of air
pollution and health research at Stanford's Sean N. Parker Center for
Allergy & Asthma Research. "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 studied a predominantly Hispanic group of children ages 6-8
in Fresno, California, a city beset with some of the country's highest air
pollution levels due to industrial agriculture and wildfires, among other
sources. Using a combination of continuous daily pollutant concentrations
measured at central air monitoring stations in Fresno, daily concentrations
from periodic spatial sampling and meteorological and geophysical data, the
study team estimated average air pollution exposures for 1 day, 1 week and
1, 3, 6 and 12 months prior to each participant visit. When combined with
health and demographics questionnaires, blood pressure readings and blood
samples, the data began to paint a troubling picture.
The researchers used a form of mass spectrometry to analyze immune system
cells for the first time in a pollution study. The approach allowed for more
sensitive measurements of up to 40 cell markers simultaneously, providing a
more in-depth analysis of pollution exposure impacts than previously
possible.
Among their findings: Exposure to fine particulate known as PM2.5, carbon
monoxide and ozone over time is linked to increased methylation, an
alteration of DNA molecules that can change their activity without changing
their sequence. This change in gene expression may be passed down to future
generations. The researchers also found that air pollution exposure
correlates with an increase in 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. Future studies are needed to verify
the long-term implications.
Hispanic children bear an unequal burden of health ailments, especially in
California, where they are exposed to higher traffic-related pollution
levels than non-Hispanic children. Among Hispanic adults, prevalence for
uncontrolled hypertension is greater compared with other races and
ethnicities in the U.S., making it all the more important to determine how
air pollution will affect long-term health risks for Hispanic children.
Overall, respiratory diseases are killing more Americans each year, and rank
as the second most common cause of deaths globally.
"This is everyone's problem," said study senior author Kari Nadeau, director
of the Parker Center. "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."
Reference:
Mary Prunicki, Nicholas Cauwenberghs, Justin Lee, Xiaoying Zhou, Hesam
Movassagh, Elizabeth Noth, Fred Lurmann, S. Katharine Hammond, John R.
Balmes, Manisha Desai, Joseph C. Wu, Kari C. Nadeau. Air pollution exposure
is linked with methylation of immunoregulatory genes, altered immune cell
profiles, and increased blood pressure in children. Scientific Reports,
2021; 11 (1) DOI:
10.1038/s41598-021-83577-3
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