Exposure weakens immune system, School of Public
Health study shows.
E-cigarettes compromise the immune system in the
lungs and generate some of the same potentially
dangerous chemicals found in traditional nicotine
cigarettes, researchers at the Johns Hopkins
Bloomberg School of Public Health report.
E-cigarettes are an emerging public health concern
as they gain popularity among current and former
smokers as well as those who have never smoked,
including teenagers. The perception that
e-cigarettes pose little health risk is so
entrenched that some smokers are switching from
cigarettes to e-cigarettes.
For their study, researchers divided mice into two
groups: one was exposed to e-cigarette vapor in
amounts that approximated actual human e-cigarette
inhalation for two weeks, while the other group was
just exposed to air. The mice exposed to the vapor
were significantly more likely to develop
compromised immune responses to when exposed to
nasal drops of the flu virus and the bacterium
responsible for pneumonia and sinusitis, which in
some cases killed the mice, the researchers found.
Their findings were published today in the journal
PLOS ONE.
"Our findings suggest that e-cigarettes are not
neutral in terms of the effects on the lungs," said
senior author Shyam Biswal, a professor in the
Department of Environmental Health Sciences at the
Bloomberg School. "We have observed that they
increase the susceptibility to respiratory
infections in the mouse models. This warrants
further study in susceptible individuals, such as
COPD patients who have switched from cigarettes to
e-cigarettes, or to new users of e-cigarettes who
may have never used cigarettes."
Since their introduction to the U.S. market in 2007,
e-cigarettes have prompted debate as to their risk
in general and relative to cigarettes. E-cigarettes,
which at their simplest consist of a battery, an
atomizer and a cartridge, produce a vapor that is
inhaled and then exhaled by the user. E-cigarettes
contain less nicotine than cigarettes, but actual
nicotine intake by e-cigarette users can approximate
that of cigarette smokers.
Previous analyses of e-cigarette vapor have
identified chemicals that could be toxic or
carcinogenic, including particulates, formaldehyde,
and volatile organic compounds, but at lower levels
than cigarette smoke.
Another thing working in the favor of e-cigarettes
in the risk continuum is that they don't combust the
way cigarettes do, limiting some of the chemicals
released in cigarette smoke.
The U.S. Food and Drug Administration last spring
announced that it was going to begin regulating
e-cigarettes. E-cigarette sales are projected to
overtake cigarette sales in the next decade, and
teen use of e-cigarettes outpaces cigarette use,
according to a recent survey released by the
National Institute on Drug Abuse. And, according to
the U.S. Centers for Disease Control and Prevention,
more than one-quarter million teenagers who reported
never having smoked a cigarette reported using
e-cigarettes in 2013.
The researchers believe this study, thought to be
the first to examine animal response to e-cigarette
inhalation, will serve as a model for future studies
on the effects of e-cigarettes.
As part of their study, the researchers also
determined that e-cigarette vapor contains "free
radicals," known toxins found in cigarette smoke and
air pollution.
Free radicals are highly reactive agents that can
damage DNA or other molecules within cells,
resulting in cell death. Cigarette smoke contains
1014 free radicals per puff. Though e-cigarette
vapor contains far fewer free radicals than
cigarette smoke—1 percent as much—their presence in
e-cigarettes still suggests potential health risks
that merit further study, the researchers say.
"We were surprised by how high that number was,
considering that e-cigarettes do not produce
combustion products," says Thomas Sussan, PhD, lead
author and an assistant scientist at the Bloomberg
School. "Granted, it's 100 times lower than
cigarette smoke, but it's still a high number of
free radicals that can potentially damage cells."
For more information
PLOS ONE
Exposure to Electronic Cigarettes Impairs Pulmonary
Anti-Bacterial and Anti-Viral Defenses in a Mouse
Model
Johns
Hopkins University
MDN |