Sexual identity differences in biomarkers of tobacco exposure among women in a national sample

1

Introduction

Tobacco use remains the leading cause of preventable death in the U.S., accounting for 480,000 deaths including cancer, cardiovascular diseases, diabetes, and pulmonary illnesses [ 1 ]. The health burden of tobacco use is largely driven by the complex mixture of over 7000 chemical compounds found in tobacco smoke, including multiple toxicants and carcinogens [ 2 ]. Examining population-level exposure to toxicants and carcinogens from tobacco, and understanding whether vulnerable populations differ in their exposure, can provide a clearer picture of the distribution of the public health burden of tobacco use [ 3 , 4 ]. This is particularly important to understand among women, who experience unique challenges related to tobacco use. Women are disproportionately affected by the health consequences of smoking [ 5 ], have a history of being targeted in tobacco marketing [ 678 ], and often face greater smoking-related stigma [ 9 , 10 ].

The most potent carcinogens associated with tobacco use include tobacco-specific nitrosamines (TSNAs) [ 1 ]. TSNAs are found in tobacco and tobacco smoke [ 11 , 12 ] and are highly specific to tobacco exposure, making these compounds excellent indicators of health risks stemming from tobacco use [ 3 , 13 , 14 ]. Nicotine derived nitrosamine ketone 4-(metylnitrosamino)-1-(3-pyridyl)-1-butanon, or NNK, is the most understood and commonly studied TSNA in epidemiologic research. The primary metabolite of NNK, 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol, or NNAL, provides utility as a biomarker of tobacco exposure as well as a direct marker of cancer risk [ 15 , 16 ]. Nicotine exposure is also critical to examine, as it is the addictive component in tobacco that contributes to tobacco use disorder. While nicotine itself is not considered carcinogenic, nicotine exposure is dose-dependently associated with tobacco use disorder severity, [ 14 , 17 ] the quantity of tobacco used, and lung cancer risk [ 14 ]. Further, evidence suggests nicotine may facilitate endogenous formation of TSNAs, induce DNA damage, and serve as a tumor promoter, underscoring the importance of examining nicotine exposure as it relates to cancer prevention and care [ 18 ].

Extant research has demonstrated a significantly greater prevalence of tobacco use among sexual minorities compared to heterosexual individuals [ 1920212223 ]. Sexual identity differences in tobacco use prevalence are most consistently found among women [ 22 , 24 , 25 ], and recent studies have found fewer or no differences in tobacco use by sexual identity among men [ 25 , 26 ]. In particular, bisexual women are consistently at greatest risk for tobacco use compared to heterosexual women [ 19 , 222324 , 27 , 28 ], and compared to gay/lesbian women using self-report survey data [ 25 ]. Bisexual and gay/lesbian women are also less likely to report receiving preventative care related to cancer and other tobacco-related health consequences including cancer screenings [ 29 ]. While evidence has clearly linked nicotine and toxicant exposure from tobacco to cancer and other tobacco-related health risks, neither biomarkers of nicotine nor tobacco toxicant exposure have been examined by sexual identity. Thus, it is not known if sexual identity differences in self-reported tobacco use prevalence among women translate into differences in biologically measured exposure to nicotine and tobacco toxicants. Biomarker data may provide an important connection to understanding the unique health risks of sexual minority women and reducing health disparities for sexual minority women.

Examining biological measures of nicotine exposure and tobacco-related toxicant exposure has important implications for understanding cancer and other health risks for sexual minority populations and can complement tobacco use data collected in surveys. Given previous research, we expect the survey data and biologically measured data to be highly correlated [ 30 ]. However, differences due to the type of tobacco product used, topography of tobacco use, and differences due to stress levels, as well as other factors, could result in differences between tobacco use survey findings and biomarker findings. In this study we had two research questions:

• 1 Does nicotine exposure and tobacco toxicant exposure differ by sexual identity among adult women in the U.S.?
• 2 Are any sexual identity differences in nicotine and tobacco toxicant exposure accounted for by self-reported differences in tobacco use?