Impact of Synthetic Coolants vs. Menthol in Cigarettes on Abuse Liability and Use Behaviors - PROJECT ABSTRACT Menthol enhances the appeal of cigarettes and promotes nicotine dependence, leading the US FDA to propose a rule prohibiting menthol as a characterizing flavor in cigarettes. However, following restrictions on the sale of menthol cigarettes in California and Massachusetts, synthetic coolants have been added to cigarettes, potentially nullifying the public health benefit of the menthol restriction. This novel study aims to provide critical knowledge to understand the abuse liability and substitutability of synthetic coolants for menthol in cigarettes, employing both laboratory and naturalistic experiments. A total of 40 adults who smoke menthol cigarettes will complete a 3-phase, 3-week study. In phase 1, participants will smoke their usual brand menthol cigarette (UBMC) during a lab session and report daily usage for a week. Phase 2 will use a double-blinded, randomized crossover design, where each participant will complete three intensive lab sessions to smoke three, lab-prepared study products varying only in the absence or presence of menthol and synthetic coolants: menthol cigarette (MC), non-menthol cigarette with synthetic coolants (NMC+SC), and non-menthol cigarette control (NMC). Data on participants’ puffing behavior and the subjective effects of the products will be collected for each session. In Phase 3, participants will be instructed to replace their UBMC with their preferred study product from Phase 2 and report daily usage and perceptions for a week to assess substitution and perceived subjective effects. This Tobacco Regulatory K01 project will yield much-needed evidence on the abuse liability and substitutability of synthetic coolants for menthol in cigarettes, while providing valuable training to a promising new investigator with guidance from leading experts in the field of tobacco regulatory science.