Arsenic exposure and tobacco consumption: Biomarkers and risk assessment.

Arsenic is measurable in tobacco and cigarette mainstream smoke (MSS). Whether arsenic has an independent role in diseases associated with tobacco consumption is not known. Epidemiology and biomonitoring data and probabilistic risk assessment (PRA) methods were used to investigate this potential association. Analysis of data from the National Health and Nutrition Examination Survey (NHANES) showed that urine arsenic concentrations in tobacco consumers were not different or were lower than levels in non-consumers of tobacco. Additionally, urine arsenic levels from NHANES tobacco consumers were five-times or more lower than levels reported in epidemiology studies to be associated with adverse health effects. Results of PRA indicated that mean non-cancer hazard estimates and mean incremental lifetime cancer risk estimates were within accepted ranges. Taken together, these results suggest that arsenic may not be independently associated with tobacco consumption or diseases related to tobacco consumption.

Cadmium exposure and tobacco consumption: Biomarkers and risk assessment.

To investigate whether cadmium has an independent role in diseases associated with tobacco consumption, epidemiology data were reviewed, biomonitoring data were analyzed, and probabilistic risk assessment (PRA) was performed. Results from previous epidemiology studies have indicated that there are adverse health effects potentially in common between cadmium exposure and tobacco consumption. Analysis of publically available biomonitoring data showed that blood (B-Cd) and urine (U-Cd) cadmium were higher in cigarette smokers compared with smokeless tobacco (SLT) consumers, and B-Cd and U-Cd in SLT consumers were not significantly different than in non-consumers of tobacco. Comparison with previously established biomonitoring equivalent (BE) values indicated that B-Cd and U-Cd in the majority of these cigarette smokers and SLT consumers did not exceed the blood and urine BEs. Results of the PRA showed that the mean hazard estimate was below a generally accepted regulatory threshold for SLT consumers, but not for cigarette smokers. In total, this evaluation indicated that cadmium exposures in tobacco consumers differed by product category consumed; cadmium in tobacco may not be associated with tobacco consumption related diseases; if cadmium in tobacco contributes to tobacco consumption related diseases, differences in hazard and/or risk may exist by product category.

A probabilistic risk assessment approach used to prioritize chemical constituents in mainstream smoke of cigarettes sold in China.

The chemical and physical complexity of cigarette mainstream smoke (MSS) presents a challenge in the understanding of risk for smoking-related diseases. Quantitative risk assessment is a useful tool for assessing the toxicological risks that may be presented by smoking currently available commercial cigarettes. In this study, yields of a selected group of chemical constituents were quantified in machine-generated MSS from 30 brands of cigarettes sold in China. Using constituent yields, exposure estimates specific to and representative of the Chinese population, and available dose-response data, a Monte Carlo method was applied to simulate probability distributions for incremental lifetime cancer risk (ILCR), hazard quotient (HQ), and margin of exposure (MOE) values for each constituent as appropriate. Measures of central tendency were extracted from the outcome distributions and constituents were ranked according to these three risk assessment indices. The constituents for which ILCR >10(-4), HQ >1, and MOE <10,000 included acetaldehyde, acrylonitrile, benzene, cadmium, formaldehyde, and pyridine. While limitations exist to this methodology in estimating the absolute magnitude of health risk contributed by each MSS constituent, this approach provides a plausible and objective framework for the prioritization of toxicants in cigarette smoke and is valuable in guiding tobacco risk management.

Differential exposure biomarker levels among cigarette smokers and smokeless tobacco consumers in the National Health and Nutrition Examination Survey 1999-2008.

Assessment of biomarkers is an appropriate way to estimate exposure to cigarette mainstream smoke and smokeless tobacco (SLT) constituents in tobacco consumers. Using the US National Health and Nutrition Examination Survey (NHANES, 1999-2008), biomarkers of volatile organic compounds, halogenated aromatic hydrocarbons (HAHs), polycyclic aromatic hydrocarbons (PAHs), acrylamide, 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK), and metals were evaluated. In general, biomarker levels in SLT consumers were significantly lower than in smokers (excluding NNK and some HAHs) and were not significantly different compared with nonconsumers (excluding NNK and some PAHs). These results provide useful information for science-based risk assessment and regulation of tobacco products.