Comprehensive E-cigarettes Study Offers Mixed Findings 

Use May Lead Youth to Start Smoking Tobacco, Adults to Quit 

January 26, 2018, 03:22 pm News Staff — Millions of Americans use electronic cigarettes (e-cigarettes) — especially those age 17 and younger, who use e-cigarettes more than any other tobacco product. And although the popularity of e-cigarettes continues to grow, little is known about the products, which only entered the U.S. market in 2006.

Key findings from the report included:

• e-cigarettes are far less harmful than conventional cigarettes, containing fewer and lower levels of toxic substances;
  
• they may help adult smokers quit smoking conventional cigarettes;
• among youth, using e-cigarettes increases the risk of transitioning to smoking conventional cigarettes; and
  
• the long-term health effects of these devices still are unknown.

"E-cigarettes cannot be simply categorized as either beneficial or harmful," said David Eaton, Ph.D., chair of the expert committee and dean and vice provost of the Graduate School of the University of Washington, Seattle, in a news release. "In some circumstances, such as their use by nonsmoking adolescents and young adults, their adverse effects clearly warrant concern. In other cases, such as when adult smokers use them to quit smoking, they offer an opportunity to reduce smoking-related illness."

The report found use varies substantially across demographic groups, including by age, gender, race and ethnicity. For example, among both youth and adults, use is typically greater among males than females, said the release.

The researchers said more and better research is still needed on the short- and long-term health effects of e-cigarettes, as well as on their relationship to conventional smoking.

Overview of Findings

The report's conclusions were wide-ranging and included the following highlights:

Exposure to nicotine

• Conclusive evidence demonstrates that the degree of exposure to nicotine from e-cigarettes is highly variable and depends on the characteristics of the device and the e-liquid, as well as on how the device is operated.
  
• Substantial evidence shows nicotine intake from e-cigarettes by experienced adult e-cigarette users can be comparable to that from conventional cigarettes.

Exposure to toxic substances

• Conclusive evidence demonstrates that in addition to nicotine, most e-cigarettes contain and emit numerous potentially toxic substances.
  
• Substantial evidence shows that except for nicotine, exposure to potentially toxic substances from e-cigarettes (under typical conditions of use) is significantly lower compared with conventional cigarettes.

Dependence and abuse liability

• Substantial evidence indicates that e-cigarette use results in symptoms of dependence on e-cigarettes.
  
• Moderate evidence suggests that risk for and severity of dependence is lower for e-cigarettes than for conventional cigarettes.
  
• There is also moderate evidence that variability in the characteristics of e-cigarette products (e.g., nicotine concentration, flavoring, device type and brand) is important in determining the risk for and severity of dependence on e-cigarettes.

Harm reduction

• Conclusive evidence indicates that completely substituting e-cigarettes for conventional cigarettes reduces users' exposure to many toxicants and carcinogens.
  
• Substantial evidence shows that completely switching from regular use of conventional cigarettes to e-cigarettes results in reduced short-term adverse health outcomes in several organ systems.

Use by youth/young adults

• There is substantial evidence to show that e-cigarette use by youth and young adults increases their risk of ever using conventional cigarettes.

Secondhand exposure

• Conclusive evidence demonstrates that e-cigarette use boosts airborne concentrations of particulate matter and nicotine in indoor environments.
  
• Moderate evidence suggests that secondhand exposure to nicotine and particulates is lower with use of e-cigarettes than with conventional cigarettes.

Cancer

• There is no available evidence on whether e-cigarette use is associated with intermediate cancer endpoints in humans.
• There is limited evidence from animal studies that used intermediate biomarkers of cancer to support the hypothesis that long-term e-cigarette use could increase the risk of cancer.

Respiratory effects

• There is no available evidence regarding whether e-cigarettes cause respiratory diseases in humans.
  
• There is moderate evidence pointing to an increased incidence of cough and wheeze in adolescents who use e-cigarettes, as well as an increase in asthma exacerbations.

Injuries and poisonings

• Conclusive evidence demonstrates that e-cigarettes can explode and cause burns and projectile injuries. This risk is significantly increased when batteries are of poor quality, are stored improperly or are being modified by users.
  
• Conclusive evidence also shows that intentional or accidental exposure to e-liquids (from drinking, eye contact or skin contact) can result in adverse health effects such as seizures, anoxic brain injury, vomiting and lactic acidosis.
  
• Finally, there is conclusive evidence to show that intentionally or accidentally drinking or injecting e-liquids can be fatal.

Reproductive and developmental effects

• No available evidence indicates whether e-cigarettes affect pregnancy outcomes.
  
• There is insufficient evidence regarding whether maternal e-cigarette use affects fetal development to draw any conclusions on this topic.

Final Thoughts

Until more definitive scientific data are available, population modeling can help estimate the balance of potential benefits and harms, according to the report's authors.

"Under the assumption that e-cigarette use increases the rate at which adults quit conventional smoking, modeling projects that use of e-cigarettes will generate a net public health benefit, at least in the short run," said the news release.

However, harms associated with higher rates of youth using conventional cigarettes after previously using e-cigarettes won't be known for decades, the release noted. "For long-range projections, the net public health benefit is substantially less, and under some scenarios, the net impact is harmful," it said.

Maximizing the potential health benefits of e-cigarettes will require "determining with more precision whether and under what conditions e-cigarettes help people quit smoking; discouraging e-cigarette use among youth through education and access restrictions; and increasing the devices' safety through data-driven engineering and design," the release concluded.

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