Analysis of Assessment Methods for Detecting Nicotine Residue and Its Impact on Humans: A Systematic Review

Introduction: Thirdhand smoke (THS) was first identified by Graham and colleagues in 1953, and nicotine was detected in household dust from smokers in 1991. Thirdhand smoke (THS) consists of toxic nicotine residues that persist on surfaces long after tobacco use, posing a significant public health concern. Individuals can be exposed to thirdhand smoke through skin contact or inhalation, particularly affecting children and infants who are most vulnerable to tobacco contaminants. This review aims to assess the effectiveness of different methods for measuring nicotine THS residues to evaluate their accuracy across various age groups. Methods: Relevant literature was sourced from databases including ProQuest (Ovid), Medline (Ovid), Embase (Ovid), Scopus, and the Cochrane Library. The timeframe for included studies ranged the last 25 years, from 1999 to 2024. Eligible participants consisted of human populations exposed to thirdhand smoke residue. For this review, the animal studies were excluded. There were no restrictions regarding age, sex, ethnicity, or nationality for participant selection. For data management and screening, the Covidence systematic tool was utilized. Data extraction was performed independently by two reviewers. This protocol was registered with PROSPERO (CRD42024574140). Results: A total of 394 studies were retrieved from 5 databases for the initial screening. A total of 67 studies included in full-text screening, and ultimately, 36 studies were selected for full review. The studies were classified into four categories based on assessment methods: (1) analysis of human secretions, including salivary or urinary tests; (2) cellular analysis utilizing cellulose substrates or paper-based materials; (3) environmental assessments, which examined outdoor surfaces, vehicles, residential spaces, and fabrics; and (4) epidemiological assessments, employing surveys or questionnaires. Non-invasive matrices such as saliva and urine were frequently utilized for biomarker analysis. The studies collectively investigated nicotine and its metabolites in human biological samples, environmental surface contamination, and thirdhand smoke (THS) exposure. They employed a diverse range of assessment tools including surveys, machine learning technique, and cellulose-based substrates. Conclusions: This review identified various selective testing methods for detecting thirdhand smoke (THS) from nicotine. These assessment methods have advantages and disadvantages and underscores the need for further research. Improving these techniques for assessment of THS could significantly improve our understanding of the impact THS has on human health.