Research Project
10251269
PROJECT SUMMARY Thirdhand smoke (THS) is a distinct public health hazard resulting from aged secondhand smoke (SHS) left behind from active smoking that absorbs into surfaces, dust, and furnishings. Multiple harmful toxicants are in THS including nicotine that reacts with ambient oxidants (e.g., nitrous acid) to create carcinogenic tobacco-specific nitrosamines and tobacco-nonspecific toxicants such as polycyclic aromatic hydrocarbons and volatile organic compounds. Electronic cigarette (EC) aerosol exposure is a source of tobacco-specific toxicants despite not generating by-products from combustion. Children are most vulnerable to THS and EC aerosol exposure and its related effects. SHS and THS differ in composition and can be assessed with biomarkers in biological samples of children with varying tobacco smoke exposure (TSE) levels, which is the cumulative exposure to SHS and THS. Methods to distinguish THS from SHS in nonsmokers are limited to assessing self-report, THS-related main metabolites and NNAL-to-cotinine ratios. Currently, there are no gold standard TSE biomarkers to differentiate exposure to THS from exposure to SHS or exposure to ECs from combustible tobacco products. Our research and others indicates child TSE results in negative health outcomes and EC aerosol exposure is linked with asthma symptoms. It is crucial to examine existing tobacco- specific and nonspecific biomarkers to assess children?s exposure to diverse tobacco/nicotine products and heterogeneous pollutants. This will provide insight on TSE classification in children and disentangle related health effects. Thus, we propose to conduct an innovative secondary analysis of National Health and Nutrition Examination Survey (NHANES) 2013-2016 data. This project will be the first to examine the prevalence, contributions, and health risks of exposure to SHS and THS among children presumed to be unexposed to any tobacco smoke and among children exposed to EC aerosol only. We will examine multiple biomarkers since proportions in SHS, THS, and likely EC aerosol, differ. NHANES data will be analyzed to distinguish child TSE groups: 1) Mixed SHS and THS group (MEG): lives with nonsmokers or smokers of combustible products only, reported SHS; 2) Predominant THS group (TEG): lives with nonsmokers or smokers, no reported SHS; 3) Predominant EC group (ECG): lives with EC only users, reported EC aerosol exposure; and 4) No/minimal TSE group (NEG): lives with nonsmokers, no reported SHS. First, we will compare tobacco-specific biomarker data with interview data to validate self-report and distinguish children into TSE groups. Then, we will use classification algorithms to identify a set of tobacco-specific and nonspecific biomarkers and ratios that best differentiates between TSE groups. Lastly, associations between TSE groups and demographics, and clinical and healthcare utilization patterns will be examined. The potential for generating results to inform the FDA-CTP is substantial as the use of child TSE biomarkers is key to assess the levels of harm attributable to exposure from THS only and EC aerosol only, which are currently unknown.
