Scientists have warned that vanillin, a common flavouring chemical in e-cigarettes, could "compromise core processes of early human development". Lab studies found that even low doses, known as nanomolar concentrations, led to early-stage cells losing the ability to develop into all cell types, and higher doses killed the cells.
Study details and findings
Researchers exposed embryonic stem cells to vanillin in a series of lab tests. "We focused on vanillin because it is frequently used in e-cigarette fluids, it is often used at high concentrations, and because we knew that embryonic cells had a channel called TRPV4 on their surfaces that would likely bind with vanillin," said study lead Professor Prue Talbot, from the University of California Riverside in the US.
The researchers said that the concentrations were "relevant to maternal EC (e-cigarette) exposure". "These changes are potentially very serious and could prevent normal development of embryos," Prof Talbot said. "Our data predict that nanomolar concentrations of vanillin may reach the embryo in pregnant women who vape."
Calls for warnings and regulation
Writing in the journal Human Reproduction, the authors added: "Clinicians should counsel patients who are pregnant or planning pregnancy about this potential harm, and regulatory agencies should consider mandatory ingredient disclosure on EC packaging."
Commenting on the study, Jacob George, professor of cardiovascular medicine at the University of Dundee, said: "This is a concerning pre-clinical finding that merits attention for future clinical research correlation. As this is research done on embryonic cells in a lab, it will need to be further clarified in human clinical trials as laboratory findings do not necessarily always translate into clinically relevant outcomes."
Expert responses
George added: "Having said that, many researchers including myself have been calling for the limiting of flavours in vapes and for further research to be done on the impact of flavourings. Whilst nicotine-containing vapes are seen as a harm reduction measure compared to tobacco cigarettes, the presence of unregulated chemicals in flavourings is a concern that needs to be addressed."
Marian Knight, professor of maternal and child population health at the University of Oxford, said: "It is important to recognise that, while in itself this lab study is well designed and carried out, the way in which cells were exposed to the vanillin is very different from how the cells of a developing embryo might come in contact with vanillin as a result of maternal vaping." She noted that many effects were observed only at levels unlikely to reach the developing foetus, but some effects were seen at levels that may be found in maternal blood, hence the importance of considering this information in discussions around vapes in pregnancy.
