Flavor chemicals contribute to the
appeal and toxicity of tobacco
products, including electronic nicotine delivery systems (ENDS). The
assortment of flavor chemicals available for use in tobacco products
is extensive. In this study, a chemistry-driven computational approach
was used to evaluate flavor chemicals based on intrinsic hazardous
structures and reactivity of chemicals. A large library of 3012 unique
flavor chemicals was compiled from publicly available information.
Next, information was computed and collated based on their (1) physicochemical
properties, (2) global harmonization system (GHS) health hazard classification,
(3) structural alerts linked to the chemical’s reactivity,
instability, or toxicity, and (4) common substructure shared with
FDA’s harmful and potentially harmful constituents (HPHCs)
flavor chemicals that are respiratory toxicants. Computational analysis
of the constructed flavor library flagged 638 chemicals with GHS classified
respiratory health hazards, 1079 chemicals with at least one structural
alert, and 2297 chemicals with substructural similarity to FDA’s
established and proposed list of HPHCs. A subsequent analysis was
performed on a subset of 173 chemicals in the flavor library that
are respiratory health hazards, contain structural alerts as well
as flavor HPHC substructures. Four general toxicophore structures
with an increased potential for respiratory toxicity were then identified.
In summary, computational methods are efficient tools for hazard identification
and understanding structure-toxicity relationship. With appropriate
context of use and interpretation, in silico methods may provide scientific
evidence to support toxicological evaluations of chemicals in or emitted
from tobacco products.