Electronic nicotine delivery systems
(ENDS), by virtue of their
highly engineered construction (plastics, glass, e-liquids), may contain
a number of emerging chemicals of concern (ECCs), including phthalates,
phenolic compounds, and flame retardants. Current knowledge regarding
the safety of ENDS may underestimate the health risks from ECCs. In
this study, we examined the types and levels of those three groups
of chemicals in the components and parts of ENDS devices, including
refill liquids, tanks/cartridges, atomizers, drip tips/mouthpieces,
and sealing materials. Our results suggest that phthalates were the
most prevalent chemicals in all tested samples, followed by parabens
and organophosphate flame retardants (OPFRs). Particularly, all measured
chemicals had significantly higher detection rates in cartridges/tanks,
drip tips/mouthpieces, and sealing materials in contrast to e-liquids
and coil samples. Among all those three types of ENDS components,
phthalates generally had the highest concentrations (0.279–3790
ng/unit) in the drip tip/mouthpiece samples, followed by the sealing
materials (0.380–508.8 ng/unit) and the empty tank/cartridge
samples (up to 761.7 ng/unit). For parabens, highest concentrations
were observed in drip tip/mouthpiece samples (1.152–130.1 ng/unit),
followed by sealing materials (0.220–30.08 ng/unit) and the
tank/cartridge samples (1.794–34.24 ng/unit). For OPFRs, tris(1,3-dichloro-2-propyl)
phosphate had the highest concentrations (39.40–774.1 ng/unit)
in all component samples. High concentrations (20.25–260.4
ng/unit) were also observed for several OPFRs in sealing materials
and drip tip/mouthpiece samples. These findings will contribute to
addressing the information gaps pertinent to the presence of ECCs
in ENDS and will warrant further studies for understanding the potential
negative health effects and to what extent those chemicals may cause
potential negative health effects when using the ENDS. The findings
will also contribute to developing evidence-based standards for the
regulatory control of the types and levels of ECCs in ENDS products.