EVALUATION OF BIOMARKERS OF THIRDHAND SMOKE TO INFORM RISK AND POLICY Pubblico

Abstract

Introduction

Thirdhand smoke (THS) is residual tobacco smoke contamination remaining on surfaces and in dust after a cigarette: is extinguished, is re-emitted into the gas phase, or reacts with oxidants and other environmental compounds to produce secondary pollutants. THS leads to involuntary exposure to tobacco smoke pollutants. The health effects and exposure pathways of THS are not fully known, resulting in a lack of sufficient evidence to create laws or regulations in response to potential health risks of exposure. The purpose of this study was, among the current population classified as secondhand smoke (SHS) exposed, to examine and describe the proportion with THS exposure and conduct a needs assessment for THS research. Methods Study objectives: 1) determine if cotinine concentrations of nonsmokers (with serum cotinine level ≤ 10 ng/mL) display two distinct exposure levels, indicating exposure to SHS and THS; 2) characterize cotinine concentrations and demographics of THS exposed people in the general U.S. population by parsing the nonsmoker population into smaller subsets; and 3) conduct a needs assessment to recommend further areas of research needed to more fully understand the risks related to THS exposure. Drawing from the NHANES 2009-2010 dataset (N=8,251), the nonsmoker subset was selected for analysis to determine whether some subjects were incorrectly classified as having been exposed to SHS when actually exposed to THS. Results Serum cotinine concentrations showed a bimodal distribution distinguishing smokers from nonsmokers. Distribution of the nonsmoker population appeared multimodal, suggesting multiple sources of exposure. For this study, THS exposure was defined as nonsmokers with zero smokers in the home and no indication of cigarettes smoked in the home. THS exposed people had serum cotinine levels ≤ 0.737 ng/mL with greatest exposure likely among Hispanics and children.

Conclusion This study suggests approximately 88% of nonsmokers are likely exposed to THS. Findings are similar with previous studies that suggest young children as a vulnerable population for THS exposure. Results confirm the need to further examine low-level toxicity of tobacco smoke constituents and redefine environmental tobacco smoke to include THS exposure. This is the first attempt at defining and describing the THS exposed population.

Table of Contents

Table of Contents

CHAPTER 1 - INTRODUCTION ......................................................................................................... 10 Introduction and Rationale ............................................................................................................. 10 Problem Statement ....................................................................................................................... 11 Purpose ....................................................................................................................................... 16 Theoretical Framework .................................................................................................................. 16 Objectives .................................................................................................................................... 16 Significance Statement .................................................................................................................. 17 Definition of Terms ........................................................................................................................ 17 CHAPTER 2 - REVIEW OF LITERATURE ............................................................................................. 19 Introduction ................................................................................................................................. 19 Burden of Disease ......................................................................................................................... 19 Morbidity and Mortality .................................................................................................................. 19 Economic burden of smoking and SHS ............................................................................................. 20 Vulnerable populations ................................................................................................................... 20 Summary ..................................................................................................................................... 21 Constituents ................................................................................................................................. 22 Therapeutic constituent: Nicotine .................................................................................................... 22 Mainstream smoke constituents ...................................................................................................... 22 SHS constituents .......................................................................................................................... 22 THS constituents .......................................................................................................................... 23 Summary .................................................................................................................................... 25 Exposure ..................................................................................................................................... 25 Smokers' exposure ....................................................................................................................... 25 SHS exposure .............................................................................................................................. 26 THS exposure .............................................................................................................................. 27 Indicators of tobacco smoke exposure ..............................................................................................28 Summary ..................................................................................................................................... 30 Adverse effects ............................................................................................................................. 30 THS ............................................................................................................................................. 31 Vulnerable populations ................................................................................................................... 31 Policy ........................................................................................................................................... 33 Federal initiatives ........................................................................................................................... 33 State smoke-free laws .................................................................................................................... 33

Attitudes, beliefs, and smoking bans................................................................................................. 34 Summary ...................................................................................................................................... 35 CHAPTER 3 - METHODOLOGY ........................................................................................................... 36 Introduction ................................................................................................................................... 36 Population and Sample .................................................................................................................... 36 Research Design and Data Collection Instruments ............................................................................... 37 Procedures and Data Analysis ........................................................................................................... 39 Limitations ..................................................................................................................................... 40 Summary ....................................................................................................................................... 40 CHAPTER 4 - RESULTS ..................................................................................................................... 42 Introduction ................................................................................................................................... 42 Findings ......................................................................................................................................... 42 Overall sample (N=8,251) ................................................................................................................ 42 Nonsmoker data .............................................................................................................................. 45 Thirdhand smoke data ...................................................................................................................... 49 Other findings ................................................................................................................................. 53 Summary ....................................................................................................................................... 55 CHAPTER 5 - CONCLUSIONS, IMPLICATIONS, AND RECOMMENDATIONS ................................................. 58 Introduction .................................................................................................................................... 58 Results and Conclusions Summary ..................................................................................................... 59 General Population ........................................................................................................................... 59 Nonsmokers .................................................................................................................................... 59 THS exposed ................................................................................................................................... 59 Strengths and Limitations ................................................................................................................. 61 Recommendations ........................................................................................................................... 62 REFERENCES .................................................................................................................................. 64 APPENDIX ...................................................................................................................................... 67 Appendix A: Comparison of exposure, deaths, and economic cost from smoking, SHS, and THS ............................................................................................................................................... 67 Appendix B: Levels of carcinogens in sidestream, secondhand, and thirdhand smoke ................................ 68 Appendix C: Diseases and other adverse effects caused from smoking (DHHS, 2004) ................................ 71 Appendix D: Histograms, combined smoker/nonsmoker data .................................................................. 74 Appendix E: Additional THS histograms .............................................................................................. 75

Tables

Table 1. Serum cotinine levels stratified by age, sex, race/ethnicity and smoking status ............................ 44 Table 2. Nonsmoker data (serum cotinine levels ≤ 10 ng/mL) by race/ethnicity ........................................ 46 Table 3. Descriptive analysis of THS exposed population, N=5873 (nonsmokers with zero smokers at home, serum cotinine ≤ 0.737 ng/mL) ............................................................................... 51 Table 4. THS exposure by sex and race/ethnicity .................................................................................. 53 Figures Figure 1. TSNA constituents of THS .................................................................................................... 15 Figure 2. Structure of cotinine compound ............................................................................................ 26 Figure 3. Exposure-effect continuum for environmental chemicals .......................................................... 29 Figure 4. Study framework ............................................................................................................... 39 Figure 5. Exposure of the U.S. Population to Tobacco Smoke: Serum Cotinine Levels (NHANES 2009-2010) .................................................................................................................................... 43 Figure 6. Mean cotinine levels for nonsmokers (≤ 10 ng/mL) based on number of smokers living at home ......................................................................................................................................... 48 Figure 7. Median cotinine levels for nonsmokers (≤ 10 ng/mL) with X number of cigarettes smoked at home ............................................................................................................................. 48 Figure 8. Nonsmoker exposure to tobacco smoke among the U.S. population .......................................... 49 Figure 9. Serum cotinine, THS exposed individuals among nonsmoking population .................................. 50 Figure 10. THS exposure among the 3-5 y age group by race/ethnicity (median, serum cotinine) .................................................................................................................................................... 52 Figure 11. Mean serum cotinine levels for THS and nonsmoker exposure to tobacco smoke by race/ethnicity ................................................................................................................................ 54 Figure 12. Median, serum cotinine concentration comparison of tobacco smoke exposure among nonsmokers and THS exposed ......................................................................................................... 54

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School	Rollins School of Public Health
Department	Career Masters of Public Health
Degree	MPH
Submission	Master's Thesis
Language	English
Research Field	Health Sciences, Public Health
Parola chiave	thirdhand smoke cotinine
Committee Chair / Thesis Advisor	Panuwet, Parinya, Emory University Barr, Dana Boyd, Emory University

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