Investigators at the University of Nebraska Medical Center
in Omaha and the University of California San Francisco have published an
important study
in JAMA Network Open on “Exposure to toxicants associated with use and
transitions between cigarettes, e-cigarettes, and no tobacco.”
Hongying Dai and colleagues looked at 55 tobacco exposure
biomarkers (mostly toxins) in the urine of adult smokers, vapers and dual users
in the first wave of the Population Assessment of Tobacco and Health Study. They compared this data with urine samples
from the same participants one year later in Wave 2, when the participants may
or may not have changed their tobacco use status.
While Dai and coauthors “found complex patterns and
heterogeneous health outcomes associated with transitions between cigarettes
and e-cigarettes,” the results can be succinctly summarized. First, “transitions from dual use or
exclusive cigarette use to exclusive e-cigarette use and transitions from any
tobacco use to no use” were associated with sharp declines in toxins. Second, “transitions
from exclusive e-cigarette use to cigarette use or dual use” were associated
with “moderate to large effect” increases in toxin levels. And third, “transition from exclusive
cigarette smoking to dual use of cigarettes and e-cigarettes” didn’t provide
any meaningful change in urinary toxins.
The authors found that “only a small percentage of [Wave 1]
exclusive cigarette smokers and dual users transitioned to exclusive
e-cigarette use at [Wave 2] (1.2%and 5.6%, respectively), which could limit
ben
efits in moving combustible cigarette smokers to less hazardous,
noncombustible e-cigarettes.” This is an
important statement, because it acknowledges less e-cigarette harm by
referencing an FDA press release from 2017 (here). More importantly, it is followed by a solid
explanation for the low transition rate to vapor: “low effectiveness in
early generations of e-cigarettes in delivering nicotine [the PATH Waves
were in 2013 and 2014, when e-cigarettes were not very effective], lack of
knowledge among cigarette users to distinguish harmful effects between dual
use and exclusive e-cigarette use, or the effects of negative public health
messaging [emphasis added, references omitted].”
All of the above is informative, but the real news from this
study is demonstrated in the following table.
It reports levels of cotinine – a breakdown product of nicotine – in the
urine of participants, according to the product they used at Wave 1, and one
year later at Wave 2. Cotinine levels
are widely used to indicate tobacco use levels.
In general, higher cotinine indicates more tobacco use. Higher cotinine, especially with cigarette
combustion, also means greater exposure to toxins.
| Urinary Cotinine Levels* at PATH Waves 1 and 2, According to Product Use |
| Wave 1 Product (n users) | Wave 1 Cotinine | Wave 2 Product/Cotinine |
|
|
|
|
| None | Cigarettes Only | E-Cigarettes Only | Dual Use |
|
|
|
|
|
|
| Cigarettes (247) | 158 | 5 |
|
|
|
| Cigarettes (1820) | 2273 |
| 2265 |
|
|
| Cigarettes (32) | 1833 |
|
| 713 |
|
| Cigarettes (257) | 3068 |
|
|
| 2522 |
|
|
|
|
|
|
| E-cigarettes (44) | 16 | 2 |
|
|
|
| E-cigarettes (14) | 502 |
| 1942 |
|
|
| E-cigarettes (121) | 727 |
|
| 470 |
|
| E-cigarettes (31) | 972 |
|
|
| 2569 |
|
|
|
|
|
|
| Dual use (42) | 213 | 6 |
|
|
|
| Dual use (315) | 2690 |
| 2628 |
|
|
| Dual use (36) | 2792 |
|
| 1192 |
|
| Dual use (252) | 3179 |
|
|
| 3374 |
*in nanograms per milliliter of urine
One can readily see that cotinine levels were high in
smokers and/or dual users in both waves.
Cotinine levels among e-cigarette users were much lower, confirming that
in 2013-14, the products did not deliver nicotine very effectively.
Everyone in the first four rows of the table smoked
cigarettes in Wave 1, so one might expect that their cotinine levels in that
wave would be the same. Instead, there
were huge differences between them, depending on where the smokers ended up at
Wave 2. The 247 smokers who had a
cotinine level of only 158 ng/ml at Wave 1 quit everything at Wave 2 and had
negligible cotinine. The highest Wave 1
cotinine levels were in smokers who continued to smoke at Wave 2, while the
smokers who ended up with e-cigarettes went from 1833 ng/ml at Wave 1 to 713 at
Wave 2.
The same is true for the other two categories: The
e-cigarette users and dual users at Wave 1 who quit completely at Wave 2 started
out with much lower cotinine levels.
The take-home message is hugely important. Tobacco users at Wave 1 may have
self-selected their Wave 2 product use based on their cotinine status at Wave
1. This says that those who quit completely,
switched to e-cigarettes, or stayed with cigarettes were entirely different
groups of smokers, each with distinct nicotine needs. Because no one can predict how individual smokers
will be able to quit, they should be provided access to all quit-smoking options.
