Millions of Americans use e-cigarettes. Despite their popularity, little is known about their health effects. Some suggest that e-cigarettes likely confer lower risk compared to combustible tobacco cigarettes, because they do not expose users to toxicants produced through combustion. Proponents of e-cigarette use also tout the potential benefits of e-cigarettes as devices that could help combustible tobacco cigarette smokers to quit and thereby reduce tobacco-related health risks. Others are concerned about the exposure to potentially toxic substances contained in e-cigarette emissions, especially in individuals who have never used tobacco products such as youth and young adults. Given their relatively recent introduction, there has been little time for a scientific body of evidence to develop on the health effects of e-cigarettes. Public Health Consequences of E-Cigarettes reviews and critically assesses the state of the emerging evidence about e-cigarettes and health. This report makes recommendations for the improvement of this research and highlights gaps that are a priority for future research. Table of Contents Front Matter Summary Summary Annex Report Conclusions by Level of Evidence 1 Introduction 2 Committee Approach Section I: E-Cigarette Devices, Constituents, and Exposures 3 E-Cigarette Devices, Uses, and Exposures 4 Nicotine 5 Toxicology of E-Cigarette Constituents 6 Research Needs: E-Cigarette Devices, Constituents, and Exposures Section II: Effects of E-Cigarettes on Health 7 Modes of Action 8 Dependence and Abuse Liability 9 Cardiovascular Disease 10 Cancers 11 Respiratory Diseases 12 Oral Diseases 13 Developmental and Reproductive Effects 14 Injuries and Poisonings 15 Research Needs: Effects of E-Cigarettes on Health Section III: Public Health Implications of E-Cigarettes 16 Combustible Tobacco Cigarette Smoking Among Youth and Young Adults 17 Smoking Cessation Among Adults 18 Harm Reduction 19 Modeling of E-Cigarette Use 20 Research Needs: Public Health Implications of E-Cigarettes 21 Concluding Observations Appendix A: Questions from the Center for Tobacco Products of the Food and Drug Administration Submitted for the Committee's Consideration Appendix B: Search Strategy and Quality Assessment Appendix C: Glossary of Terms Related to E-Cigarettes Appendix D: Cytotoxicity Tables Appendix E: Public Meeting Agenda Appendix F: Committee Biosketches