18.5.1 Summary of the major conclusions about chemicals in e-cigarettes

E-cigarette aerosols contain hundreds of chemicals, with many having associated health and safety concerns. Most of the chemicals with potential toxic effects are present only at low levels, so the dose of each chemical during a single puff of an e-cigarette is also low. The low doses of most of these chemicals are not associated with known toxicities, but for many, there is little data available—so this lack of known harms is not a good indicator of lack of risk. It is also important to remember that dose is not the only factor affecting the risk of health effects from chemicals with toxic effects: more frequent use, longer duration of use, the route of entry through the lungs and the mix of many different chemicals with potential to do harm—all increase the risk of harm to e-cigarette users.

The health effects of almost one-third of the chemicals in e-cigarette aerosols are unknown, and over 80% have little information on inhalation toxicity and cannot be assumed to be safe.¹ Chemicals where the health concerns have been investigated have generally only been tested in the short term. There is also great variety in the unregulated construction and use of e-cigarettes, some of which might be shedding toxic metals from the internal materials such as the heating coil.² The use of custom- and home-made e-liquid mixes, and the decay of their constituent chemicals over time, also make it difficult to determine the exact types and doses of chemicals to which users are exposed.

Some chemicals with potential toxic effects have been banned by Australia’s Therapeutic Goods Administration (TGA) as ingredients in the e-liquids of therapeutic vapes available from pharmacies.³ Two of these (benzaldehyde and cinnamaldehyde) were found in a high proportion of e-cigarettes available internationally and in e-cigarettes sold in Australia illegally, outside of the regulated pharmacy supply arrangements⁴ (see Section 18.5.5.2).

Most of the chemicals with toxicity concerns in e-cigarettes are present at considerably lower levels than in conventional cigarettes but this does not mean that e-cigarettes can be assumed to be harmless. Many people who use e-cigarettes have either never smoked, or are dual users of e-cigarettes and conventional cigarettes (see Section 18.3.1.2). Dual use of both products may further increase health risks beyond use of either product alone. For those who use e-cigarettes to quit smoking, some will sustain long-term vaping, the health risks of which are unknown. 

There are known pulmonary, cardiovascular effects and oral health effects for e-cigarette users, as well as effects on pregnancy outcomes (see Section 18.6). These health effects are likely to be caused by exposure to the chemicals in e-cigarette aerosols.

Given the lack of data on long-term inhalation toxicity for many e-cigarette chemicals, and the known pulmonary and cardiovascular effects after short-term use, there is currently insufficient evidence to support the safety of long-term e-cigarette use.  

Related reading

References

1. National Health and Medical Research Council. Inhalation toxicity of non-nicotine e-cigarette constituents: risk assessments, scoping review and evidence map.  2022. Available from: https://www.nhmrc.gov.au/file/18287/download?token=Z5D5_sam.

2. Olmedo P, Goessler W, Tanda S, Grau-Perez M, Jarmul S, et al. Metal concentrations in e-cigarette liquid and aerosol samples: the contribution of metallic coils. Environmental Health Perspectives, 2018; 126(2):027010. Available from: https://www.ncbi.nlm.nih.gov/pubmed/29467105

3. Therapeutic Goods (Standard for Therapeutic Vaping Goods) (TGO110) Order 2021. Available from: https://www.legislation.gov.au/F2021L00595/latest/text.

4. Larcombe A, Allard S, Pringle P, Mead-Hunter R, Anderson N, et al. Chemical analysis of fresh and aged Australian e-cigarette liquids. Medical Journal of Australia, 2022; 216(1):27-32. Available from: https://www.ncbi.nlm.nih.gov/pubmed/34528266