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 The researchers focused on what’s known as peptic ulcers, or painful
sores lining the stomach or small intestine, which are often caused
by bacterial infections but have also been linked to drinking,
smoking and certain medications. Untreated bleeding ulcers can lead
to bloody vomit or stool, anemia and life-threatening blood loss
that requires hospitalization.
Researchers examined whether short-term spikes in air pollution
could also influence the risk of serious bleeds, and estimated a 7.6
percent increased risk of emergency admissions for bleeding peptic
ulcers during five-day periods with higher average nitrogen dioxide
levels.
“We already knew that air pollution exposure may alter intestinal
immunity, increase gut permeability and influence intestinal
microbial composition, which may contribute to the development of
various intestinal diseases,” said senior study author Wai-Keung
Leung of the University of Hong Kong.
“This is the first time that the association between air pollution
and peptic ulcer bleeding, one of the most important complications
of peptic ulcer, is being reported,” Leung said by email.
For the study, researchers examined data on air pollution levels in
Hong Kong and 8,566 emergency admissions for bleeding peptic ulcer
in adults 65 and older from 2005 to 2010.
In addition to nitrogen dioxide, they also looked at concentrations
of ozone, an unstable form of oxygen produced when various types of
traffic and industrial pollution react with sunlight; sulfur
dioxide, a byproduct of fossil fuel combustion and refining minerals
like copper, aluminum and iron; and so-called PM 2.5, a mixture of
solid particles and liquid droplets smaller than 2.5 micrometers in
diameter that can include dust, dirt, soot and smoke.
They also considered factors that can influence air quality like
temperature, humidity and other weather conditions.
Out of all the air pollutants, only elevated nitrogen dioxide levels
were independently associated with an increased risk of emergency
admissions for bleeding peptic ulcer, the study team reports in The
Lancet Planetary Health.
One limitation of the study is its use of air quality readings on
the date of the emergency admission to examine the link between the
pollutants and bleeding peptic ulcers because, the authors note,
it’s possible some people might have developed symptoms triggered
several days before they went to the hospital.
Researchers also didn’t have data on other risk factors for bleeding
peptic ulcer such as infections with H. pylori bacteria or regular
use of non-steroidal anti-inflammatory (NSAID) medications like
aspirin and ibuprofen.
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The results from Asian residents of Hong Kong also might differ from
what would be found in other racial or ethnic groups because some
people can have a genetic predisposition to this health problem.
An earlier study in Canada with a mostly white population didn’t
find an association between nitrogen dioxide and bleeding peptic
ulcer, the author of that study, Dr. Gilaad Kaplan of the University
of Calgary, writes in an accompanying editorial.
However, residents of Hong Kong were exposed to much higher levels
of nitrogen dioxide than people in the Canadian study, Kaplan notes
in the editorial.
“Air pollution is a modifiable risk factor that is linked to
diseases throughout the body from the respiratory system to the
cardiovascular system, with growing evidence that it may influence
the gastrointestinal tract,” Kaplan told Reuters Health by email.
“As a modifiable risk factor, people who are at risk for the adverse
health effects of air pollution can take action to protect
themselves on days when air pollution levels spike locally by
avoiding larger sources of pollution when reasonably possible (e.g.
avoiding jogging near heavy traffic, working earlier in the day to
avoid the worst of rush hour traffic),” Kaplan added. “Moreover,
society needs to prioritize actions to continue to improve the air
quality of cities.”
SOURCE: http://bit.ly/2t1OiIZ and http://bit.ly/2rrdETq The Lancet
Planetary Health, online May 5, 2017.
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