The study, “The effect of smoking and electronic cigarettes on rat testicles,” divided adult male wistar rats into groups. One group was exposed to cigarette smoke, the second to e-cigarette vapour and a third control group to none. Subsequently urine cotinine levels, testicular weights, gonadosomatic index, sperm count and sperm motility, testicular histology, and biochemical findings were compared among the three groups.
The results indicated that both the rats in the cigarette and vape group experienced changes in their testicles due to oxidative stress, even though as expected the cigarette group did indicate some higher markers than the vape group. Moreover, the average sperm count in both groups decreased from about 98.5 million per milliliter, to an average of 95.1 million sperm per milliliter.
We asked medical professional and tobacco harm reduction expert Dr. Colin Mendelsohn, for his opinion on these findings, as well as on those of other studies looking into the relationship between vaping and fertility. “From the abstract, some changes were found in rats from smoke and vape exposure, but the difference between the groups (smoke and vape) is not clear and the magnitude is not stated. So again, it is impossible to draw any conclusions on the significance of these findings. Also, it is not appropriate to extrapolate the findings to humans who vape,” said Dr. Mendelsohn about the current study.
Extrapolating conclusions from animal studies may not be appropriate
Another study looking into the possible effects of vaping on reproductive health, consisted of a review of several studies. The review reported that although most of the studies analysed found that toxins in vaping products were detected at much lower levels than the ones found in cigarettes, concerns on both the male and the female reproduction system were identified. However, once again this information was obtained mainly from animal studies, as rightly highlighted by the study authors.
“As the authors state, there are changes demonstrated in animal studies under conditions that do not replicate vaping by humans. It is not possible or appropriate to extrapolate these findings to humans. Human studies are needed to make any meaningful conclusions about human health,” explained Dr. Mendelsohn.
Vaping and erectile dysfunction
While a 2021 study published in the American Journal of Preventive Medicine said that the use of electronic nicotine delivery systems (ENDS) was associated with erectile dysfunction (ED) independent of age, heart disease, and other factors in men. The study specified that males who vaped regularly were more than twice as likely to report suffering from erectile dysfunction than non users.
Dr. Mendelsohn told Vaping Post that there were a number of problems with this study.
“• The past or current smoking status is not clear. There is possible reverse causation, ie that men who suffered ED or other complications from smoking are more likely to take up vaping. In other words, it is more likely that past smoking caused the ED, not vaping
• It is cross-sectional, so causation cannot be inferred, as implied.
• Paradoxically, smokers had no increase in ED. This calls into question the validity of the findings,” he clarified.
Given that science has shown that erectile dysfunction may be linked to vascular health, experts in the field could argue that any effects vapes would have on cardiovascular health, may also translate into erectile and fertility issues in users. A study titled “Chronic e-cigarette use impairs endothelial function on the physiological and cellular levels. Arteriosclerosis, Thrombosis, and Vascular Biology,” found that regular vapers had impaired blood vessel function, potentially putting them at risk for heart disease
Collecting blood samples from 120 participants who were either long-term vapers, long term smokers or neither, the researchers found that the combined use of vapes and cigarettes put users at a greater risk, than the use of either of these products alone.
The relative benefits of smokeless tobacco products
On the other hand, a study published in the journal Nicotine and Tobacco Research, highlighted the relative safety of smokeless tobacco products and how switching to them from combustible cigarettes was associated with lower cardiovascular disease risk in smokers.
The study, “Associations of Smokeless Tobacco Use With Cardiovascular Disease Risk: Insights From the Population Assessment of Tobacco and Health Study” was conducted by a team of researchers from UCLA, UC San Francisco, Boston University and the University of Texas at Arlington.
The researchers analyzed data from a nationally representative group of 4,347 adults who provided urine and blood samples in 2013–14 as part of the Population Assessment of Tobacco and Health (PATH) Study. Among this group, 3,034 participants used cigarettes exclusively, 338 used only smokeless tobacco, and 975 had never used any tobacco product.
The research team analysed the participants’ samples for biomarkers of tobacco exposure, inflammation and oxidative stress, which are predictors of cardiovascular disease risk, in each of the three subgroups.
The compiled data indicated that despite similar nicotine levels, smokeless tobacco users displayed significantly lower biomarkers of disease. “Our findings show that despite having higher levels of nicotine, exclusive smokeless tobacco users had significantly lower concentrations of inflammation and oxidative stress biomarkers than cigarette smokers. Levels of these biomarkers among smokeless tobacco users were similar to those of ‘never’ smokers,” said lead study author Mary Rezk-Hanna, who is an assistant professor at UCLA School of Nursing.