Prevalence of Underreported Nicotine Exposure Among US Nonsmoking Adults: A Comparison of Self-Reported Exposure and Serum Cotinine Levels From NHANES 2013-2020

Introduction Secondhand smoke (SHS) poses a significant health risk. However, individuals who do not smoke may be unaware of their exposure, thereby failing to take protective actions promptly.Aims and Methods We assessed the prevalence of underreported nicotine exposure in a nationally representative sample of US nonsmoking adults using data from the US National Health and Examination Survey. Individuals with underreported nicotine exposure were defined as those who reported no exposure to all tobacco products (traditional tobacco, nicotine replacements, and e-cigarettes) or SHS, yet had detectable levels of serum cotinine (>0.015 ng/mL). We fitted logistic regression models to determine sociodemographic and chronic condition factors associated with underreported nicotine exposure.Results Our analysis included 13 503 adults aged 18 years and older. Between 2013 and 2020, the prevalence of self-reported SHS exposure, serum cotinine-assessed nicotine exposure, and underreported nicotine exposure among US nonsmokers were 22.0%, 51.2%, and 34.6%, respectively. Remarkably, 67.6% with detectable serum cotinine reported no SHS exposure. Males, non-Hispanic blacks, individuals of other races (including Asian Americans, Native Americans, and Pacific Islanders), and those without cardiovascular diseases were more likely to underreport nicotine exposure than their counterparts. The median serum cotinine value was higher in respondents who reported SHS exposure (0.107 ng/mL) than in those who reported no exposure (0.035 ng/mL). We estimate that approximately 56 million US residents had underreported nicotine exposure.Conclusions Over a third of US nonsmokers underreport their nicotine exposure, underlining the urgent need for comprehensive public awareness campaigns and interventions. Further research into sociodemographic determinants influencing this underreporting is needed.Implications Understanding the extent of underreported nicotine exposure is crucial for developing effective public health strategies and interventions. It is imperative to bolster public consciousness about the risks associated with SHS. Additionally, surveillance tools should also incorporate measures of exposure to outdoor SHS and e-cigarette vapor to enhance the quality of data monitoring. Findings from this study can guide tobacco control initiatives and inform smoke-free air legislation.