Quantitative risk assessment (QRA)-based prioritization of mainstream cigarette smoke toxicants
In 2008, seven representative toxicants in mainstream cigarette smoke were screened and validated by China Tobacco to indicate the harmfulness of mainstream cigarette smoke, which included carbon monoxide (CO), hydrogen cyanide (HCN), 4-(N-methyl-nitrosamine)-1-(3-pyridyl)-1-butanone (NNK), ammonia (NH3), benzo[a]pyrene (B[a]P), phenol, and crotonaldehyde. A hazard index based on these seven representative toxicants was then used to regulate the cigarette products of CNTC. In order to more accurately evaluate the harmfulness of cigarettes smoke, a quantitative risk assessment (QRA)-based method of harmful toxicants in cigarette smoke was developed, which consisted of hazard identification, dose-response evaluation, exposure evaluation and risk characterization. Based on the toxicological data in the database of the International Agency for Research on Cancer (IARC), the California Environmental Protection Agency (Cal/EPA), and the U.S. Environmental Protection Agency (US EPA), the toxic potencies of the seven representative toxicants were identified. Exposure evaluation of the seven representative toxicants was performed based on the delivery of mainstream cigarette smoke and parameters of smoking behavior of the Chinese populations (cigarettes smoked per day, exposure frequency, duration of exposure). The quantitative risk of the seven representative toxicants in mainstream cigarette smoke was evaluated by three methods, including incremental lifetime cancer risk (ILCR), hazard quotient (HQ), and margin of exposure (MOE), and a weight-based hazard index of the seven representative harmful toxicants in mainstream cigarette was proposed.