Removal of Tobacco Specific Carcinogenic Nitrosamines in Mainstream Cigarette Smoke and Aqueous SolutionA Review

Abstract

Tobacco-specific N-nitrosamines (TSNAs), which are associated with several cancers, are formed during the processing of tobacco alkaloids. Since tobacco smoking poses serious health risks, scientists, governments, and health regulators globally have denounced it and categorized its constituents according to their carcinogenicity. Tobacco smoke investigations are guided by standardized methods (ISO). With the help of standardized smoke-generating machines, precise quantification of TSNAs and other smoke constituents is now possible thanks to advancements in analytical techniques. This information supports initiatives to reduce the amount of TSNAs that smoking exposes people to. This review covers the occurrence, formation pathways, precursors, and control strategies through removal technologies, providing thorough analysis of the state of science today regarding TSNAs. The adsorption characteristics of different materials as possible filter additives or modifiers are critically discussed, emphasizing important elements like porosity, layering, acidity/alkalinity, and surface area that affect their performance for capturing TSNAs from smoke. While scientific understanding of these areas is still evolving, this review intends to provide for the first time research progress on the adsorption properties of various materials, including zeolites, silica, few-layer black phosphorus, metal-organic frameworks, and molecularly imprinted polymers, among others, for reducing TSNAs present in both cigarette smoke and aqueous solutions.

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Chemical structures of major and minor alkaloids in tobacco and tobacco-specific N-nitrosamine formation pathway.

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Scheme representing the elution part of the online solid phase extraction (SPE) system. Reproduced with permission from ref . Copyright 2016 Elsevier.

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(a) Chromatogram of NNN: (1) directly injected into the analytical column without online SPE cleanup, (2) underwent only the PRS cartridge cleanup, (3) underwent only the C18 HD cartridge cleanup, and (4) underwent both PRS and C18 HD cartridges for cleanup. (b) Total ion chromatogram of mainstream smoke NNK, NAT, NNN, and NAB with different LC columns. (1) Xterra MS C18 (2.1 mm × 50 mm, 2.5 μm). (2) SHISEIDO MGII (2 mm × 50 mm, 3 μm). (3) ACQUITY UPLC CSH C18 (3.2 mm × 100 mm, 1.7 μm). Reproduced with permission from ref . Copyright 2016 Elsevier.

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(a) Sandwiched multiwalled carbon nanotubes membrane showing the removal of toxins and the SEM of the filter before and after smoking. (b) The FTIR spectra of the membrane before and after smoking. Reproduced from ref . Copyright 2020 American Chemical Society.

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(a) Synthesis of the cellulose nanofiber-silica cigarette butt. SEM images of the cigarette butt (b) before smoking experiments and (c) after smoking experiments. Reproduced from ref . Copyright 2022 American Chemical Society.

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(a) Incorporation of FeOx into the AC pores to promote the adsorption of TSNAs. (b) Coconut shell AC with FeO _x mimicking a zeolite-like structure. Reproduced with permission from ref . Copyright 2018 Elsevier.

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(a) Pore size spread and (b) zeta potential of AC and AC modified with 10% FeO _x (10Fe*AC-g). Reproduced with permission from ref . Copyright 2018 Elsevier.

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(a) LC chromatogram of TSNAs without additives, (b) reduction percentage of TSNAs with different additives, and (c) probable TSNA reduction mechanism by NaY and SBA-15. Reproduced with permission from ref . Copyright 2013 Elsevier.

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(a) Schematic of the cigarette with the additives and (b) concentration of the TSNAs and total particulate matter removed from the mainstream smoke. Reproduced with permission from ref . Copyright 2015 John Wiley and Sons.

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(a) Gas chromatography peak areas and (b) solution color of unadsorbed nicotine after adsorption experiments using cellulose filter modified with various MOFs. Reproduced from ref . Copyright 2023 American Chemical Society.