More evidence that IQOS and ecigs are as bad for human lungs as cigs

Pawan Sharma and colleagues recently published “IQOS exposure impairs human airway cell homeostasis: direct comparison with traditional cigarette and e-cigarette” in which they measured a wide range of effects of cigarette smoke extract (from Philip Morris’ Marlboro cigarettes, Philip Morris International’s heated tobacco product IQOS, and an e-cig using Blu liquid) on human lung cells.  All three products adversely affected lung cells with a dose-response (i.e., bigger effects at higher doses).

In this study they exposed lung from the lining of the bronchi (big air pipes) and airway smooth muscle cells in vitro (i.e., cells in “test tubes”) to solutions made from the aerosols from all three products.

Here is my simplified version of their summary:

IQOS exposure is as detrimental as cigarette smoking and vaping to human lung cells. Persistent allergic, smoke or environmental-triggered inflammation leads to airway remodelling/scarring and disturbing the way that cells convert oxygen into energy for the cells to use (mitochondrial dysfunction) plays a pivotal role in this process. These are the principal causes for airflow limitation in asthma and COPD. They analyzed all of these mechanisms and found that like eCigs and traditional cigarettes, IQOS exposure contributes to altered mitochondrial function which can further exaggerate airway inflammation, airway remodelling and lung cancer, as seen in smokers. Mitochondrial dysfunction also underpins many normal physiological processes and in certain pathological conditions, such as obesity or with an oxidant trigger such as smoke, eCigs and IQOS, it may impact lung diseases. Cigarette smoking and eCigs can exaggerate respiratory infections by increasing microbial adherence to the airways; IQOS may increase respiratory infections through similar mechanisms.

Given our current findings and those of previous studies, in a manner very similar to cigarette smoke and eCigs, IQOS has the potential to increase oxidative stress and inflammation, infections, airway remodelling and initiate changes in the airways of users of these devices.

PMI and Imperial Tobacco (which owns blue cigs) provided the expected criticism of the study, citing Public Health England, with several other harm-reduction enthusiasts chiming in.

The obvious limitation of experimental studies on isolated cells is that it is an experimental study on isolated cells.  The advantage of such studies is that they can be highly controlled and give insights into the biological mechanisms by with cigarettes, HTP like IQOS, and e-cigs cause lung disease, something that generally can’t be done in human epidemiological studies.  Considering both kinds of information together, supports and overall conclusion that these products cause lung disease in humans. There are epidemiological studies of cigarettes and e-cigarettes; there are not yet any data on IQOS at the population level, but this experimental study raises serious concerns. 

And, while PMI is critical, the fact is that a careful reading of the data PMI submitted to the FDA to try and get permission to market IQOS in the US with modified risk claims revealed substantial pulmonary toxicity, a point that my colleagues from pulmonary medicine pointed out in a peer-reviewed paper and public comment to the FDA.

The full citation is Sukhwinder Singh Sohal, Mathew Suji Eapen, Vegi G.M. Naidu, Pawan Sharma.  ERJ Open Research 2019 5: 00159-2018; DOI: 10.1183/23120541.00159-2018.  It is available here.