Five metals, toxic and potentially carcinogenic when
inhaled, found in liquid of leading first generation
e-cigarette brands.
A study led by researchers at the Johns Hopkins
Bloomberg School of Public Health found high levels
of toxic metals in the liquid that creates the
aerosol that e-cigarette users inhale when they vape.
The study, believed to be the first to examine a
cross-section of metals in multiple e-cigarette
brands, analyzed the liquid in five brands of first
generation e-cigarettes for cadmium, chromium, lead,
manganese and nickel.
The liquid is the component of e-cigarettes that,
when heated, delivers ingredients, often including
nicotine and flavors, to the user.
In first generation e-cigarettes, the liquid is
stored in the cartridge in close contact with the
heating coil. The researchers found all five heavy
metals – which can be toxic or carcinogenic when
inhaled – in all five brands, though levels varied
by brand. The main source of the metals, the
researchers believe, is the coil that heats the
liquid that creates the aerosol, which is often but
erroneously referred to as vapor. The study did not
look at the possible presence of metals in
e-cigarette aerosol.
The findings appear in the January issue of the
journal Environmental Research.
“We do not know if these levels are dangerous, but
their presence is troubling and could mean that the
metals end up in the aerosol that e-cigarette users
inhale,” says study leader Ana María Rule, PhD, MHS,
an assistant scientist in the Bloomberg School’s
Department of Environmental Health and Engineering.
“One of the things that is troubling is that the
metals in e-cigarette coils, which heat the liquid
that creates the aerosol, are toxic when inhaled, so
perhaps regulators might want to look into an
alternative material for e-cigarette heating coils.”
The Food and Drug Administration began regulating
e-cigarettes last year, but has not yet issued
warnings.
E-cigarettes may be less harmful than cigarettes for
current smokers who switch completely to electronic
cigarettes.
A serious concern is the appeal of e-cigarettes to
young people who have never smoked, since
e-cigarettes might be habit forming, and might not
be totally safe as emerging research shows that
nicotine can adversely affect the developing
adolescent brain.
Last fall, then-U.S. Surgeon General Vivek Murthy
called e-cigarette use by young people a serious
concern.
E-cigarette use among high school students jumped
900 percent between 2011 and 2015.
For their study, the researchers selected five
leading brands of so-called first generation
e-cigarettes, which are referred to as cig-a-likes
because they resemble traditional cigarettes. (Newer
ones look like small cassette recorders with a
mouthpiece. In the newer devices the liquid is added
from a dispenser prior to use. In contrast, the
liquid in first generation e-cigs is stored in the
cartridge together with the coil, which increases
the liquid’s exposure to the coil even in the
absence of heating.) The five brands are sold across
the United States in big-box retail stores,
convenience stores and gas stations, as well as
online. Three of the five brands constituted 71
percent of total market share in 2015. If a brand
came in more than one flavor, the researchers chose
one flavor for consistency’s sake.
To test the liquid for metal levels, the researchers
extracted samples of the liquid; the liquid had not
been heated by the coil prior to extraction. The
liquid is a mixture of propylene glycol, glycerin,
nicotine and flavorings. Because liquid volume
varied considerably from brand to brand, the
research team tested for concentrations of metals in
micrograms per liter.
The five metals – cadmium, chromium, lead, manganese
and nickel – were present in all five brands, with
cadmium markedly lower than the other metals and
with a considerable range of concentrations among
the brands.
For instance, one brand had a high concentration of
all five metals. In that brand, the concentration of
nickel, which is considered the most serious
carcinogen when inhaled, was 22,600 micrograms per
liter, 400 times that of the brand with the lowest
concentration of nickel.
In that same brand, the one with the highest
concentration of all five metals, the concentration
of manganese was 690 micrograms per liter, or 240
times that of the lowest concentration in yet
another brand.
“It was striking, the varying degrees to which the
metals were present in the liquid,” Rule says. “This
suggests that the FDA should consider regulating the
quality control of e-cigarette devices along with
the ingredients found in e-cigarette liquids.”
For now, FDA regulations require e-cigarette makers
to submit ingredient lists as well as information
about potentially harmful ingredients, including
four of the five metals analyzed in this study –
nickel, lead, chromium and cadmium.
The FDA has yet to issue proposed regulations on
e-cigarette labeling. In addition to the coil, the
researchers believe some of the metals may come from
the components of the e-cigarette device or the
manufacturing process.
“E-cigarettes as a source of toxic and potentially
carcinogenic metals” was written by Catherine Ann
Hess, Pablo Olmedo, Ana Navas-Acien, Walter Goessler,
Joanna E. Cohen and Ana María Rule.
This study was funded by the Institute for Global
Tobacco Control, Johns Hopkins School of Public
Health; National Institute of Environmental Health
Sciences Training Grant T32ES007141-31A1; National
Institute on Alcohol Abuse and Alcoholism Training
Grant T32-AA014125 and the Alfonso Martín Escudero
Foundation.
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Johns Hopkins Bloomberg School of Public Health
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