The lure of 'Healthier Smoke': Comparative physical, chemical, and oxidative potential characterization of emissions from herbal and tobacco cigarettes

Abstract

Herbal cigarettes (HC) are perceived as safer, nicotine-free alternatives, often with therapeutic claims. However, such unverified claims can mislead smokers and encourage non-smokers to start smoking, under the guise of being harmless or even beneficial. Despite their growing popularity, comprehensive evidence evaluating emissions from herbal cigarettes and associated health impacts remains limited. This study investigates physical (size distribution and gravimetric sampling), chemical (metals and carbonaceous content), and oxidative potential (OP) characterization of particulate matter (PM) emissions from herbal and tobacco cigarettes (TC). Sub-500 nm particle concentrations were ∼20% higher in HC than in TC. Chemical analysis showed comparable or elevated levels of organic and elemental carbon in HC emissions, with no consistent trend for trace metal content. Intrinsic OP was measured using two acellular assays: dithiothreitol (DTT) consumption (OP_m^DTT) and hydroxyl radical (⋅OH) generation (OP_m^OH). The OP_m^DTT (pmol/μg-min) of emitted PM was significantly higher for HC (24 ± 6) than TC (18 ± 5), while the OP_m^OH was comparable for both cigarette types. Emissions were strongly influenced by wrapper and filler composition, with leaf-wrapped cigarettes exhibiting consistently higher particle concentrations and OP than paper-wrapped cigarettes. Our findings indicate that the emissions characteristics of HCs matched or even exceeded those of TCs, suggesting that HCs are as hazardous as TCs and underscoring the urgent need for regulatory oversight guided by a comprehensive toxicological evaluation of herbal cigarettes.

Keywords: Herbal cigarettes; Oxidative potential; Particle composition; Particle size-distribution; Reactive oxygen species.