A commonly used vanilla flavouring in e-cigarettes may interfere with early development of unborn babies, according to a new laboratory study, prompting scientists to urge pregnant women and those planning a pregnancy to be cautious.
Researchers examined the effects of vanillin, a chemical commonly used to create vanilla flavour in vape liquids. Their findings, published in Human Reproduction, suggested that the substance could interfere with key processes involved in early human development.
The study found that even low concentrations of vanillin caused embryonic stem cells to lose their ability to develop into different types of cells. At higher concentrations, the cells were killed altogether.
Professor Prue Talbot from the University of California Riverside, who led the study, said the changes observed were potentially serious and could interfere with the normal development of embryos.
The researchers said vanillin was selected because it is frequently used in e-cigarette liquids and can be present at relatively high concentrations. They also noted that laboratory findings suggested the chemical could potentially reach an embryo in pregnant women who vape.
However, experts stressed that the findings should be interpreted with caution as the research was conducted on embryonic cells in a laboratory rather than directly on pregnant women.
Professor Jacob George of the University of Dundee described the findings as concerning but said further clinical research involving humans would be needed to determine whether the laboratory results translate into actual health effects.
Other experts similarly highlighted limitations in the research, noting that the way the cells were exposed to vanillin differs from how a developing embryo would encounter the chemical inside the body.
Professor Marian Knight of the University of Oxford said some of the effects were observed only at concentrations unlikely to reach a developing foetus, although other findings occurred at levels that may potentially be present in maternal blood.
Despite the uncertainty, researchers said pregnant women and those planning to conceive should be made aware of the potential risks. They also called on regulators to consider requiring vape manufacturers to disclose all ingredients on product packaging.
Health authorities already advise against vaping during pregnancy. While vaping is generally considered less harmful than smoking cigarettes and is sometimes used by adult smokers as a quitting aid, it is not risk-free.
The long-term health effects of vaping also remain unclear, while nicotine exposure during pregnancy is known to pose risks to developing babies.
The findings add to wider concerns surrounding flavoured vaping products, with regulators in the UK also considering tighter rules on vape colours, packaging and flavour names in an effort to make the products less attractive to children.
