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IntroductionThirdhand smoke (THS) is ultrafine particulate matter and residue resulting from tobacco combustion, with implications for health-related harm (eg, impaired wound healing), particularly among hospitalized infants. Project aims were to characterize nicotine (THS proxy) transported on neonatal intensive care unit (NICU) visitors and deposited on bedside furniture, as well as infant exposure.MethodsCross-sectional data were collected from participants in a metropolitan NICU. Participants completed a survey and carbon monoxide breath sample, and 41.9% (n = 88) of participants (n = 210) were randomly selected for finger-nicotine wipes during a study phase when all bedside visitors were screened for nicotine use and finger-nicotine levels. During an overlapping study phase, 80 mother-infant dyads consented to bedside furniture-nicotine wipes and an infant urine sample (for cotinine analyses).ResultsMost nonstaff visitors' fingers had nicotine above the limit of quantification (>LOQ; 61.9%). Almost all bedside furniture surfaces (93.8%) and infant cotinine measures (93.6%) had values >LOQ, regardless of household nicotine use. Participants who reported using (or lived with others who used) nicotine had greater furniture-nicotine contamination (Mdn = 0.6 [interquartile range, IQR = 0.2-1.6] µg/m2) and higher infant cotinine (Mdn = 0.09 [IQR = 0.04-0.25] ng/mL) compared to participants who reported no household-member nicotine use (Mdn = 0.5 [IQR = 0.2-0.7] µg/m2; Mdn = 0.04 [IQR = 0.03-0.07] ng/mL, respectively). Bayesian univariate regressions supported hypotheses that increased nicotine use/exposure correlated with greater nicotine contamination (on fingers/furniture) and infant THS exposure.ConclusionsPotential furniture-contamination pathways and infant-exposure routes (eg, dermal) during NICU hospitalization were identified, despite hospital prohibitions on tobacco/nicotine use. This work highlights the surreptitious spread of nicotine and potential THS-related health risks to vulnerable infants during critical stages of development.ImplicationsTHS contamination is underexplored in medical settings. Infants who were cared for in the NICU are vulnerable to health risks from THS exposure. This study demonstrated that 62% of nonstaff NICU visitors transport nicotine on their fingers to the NICU. Over 90% of NICU (bedside) furniture was contaminated with nicotine, regardless of visitors' reported household-member nicotine use or nonuse. Over 90% of infants had detectable levels of urinary cotinine during NICU hospitalizations. Results justify further research to better protect infants from unintended THS exposure while hospitalized.

IntroductionThirdhand smoke (THS) residue results from secondhand smoke, and is emerging as a distinct public health hazard, particularly for medically fragile pediatric patients living with smokers. THS is difficult to remove and readily reacts with other pollutants to form carcinogens and ultrafine particles. This study investigated THS found in homes of high-risk infants admitted to a neonatal intensive care unit and their association with characteristics (eg, number of household smokers) hypothesized to influence THS.MethodsBaseline data from 141 hospitalized infants' homes were analyzed, along with follow-up data (n = 22) to explore household smoking characteristics and THS changes in response to indoor smoking ban policies.ResultsHouseholds with an indoor ban, in which not more than 10 cigarettes/d were smoked, had the lowest levels of THS contamination compared to homes with no ban (P < .001) and compared to homes with an indoor ban in which greater numbers of cigarettes were smoked (P < .001). Importantly, homes with an indoor ban in which at least 11 cigarettes/d were smoked were not different from homes without a ban. The follow-up sample of 22 homes provided initial evidence indicating that, unless a ban was implemented, THS levels in homes continued to increase over time.ConclusionsPreliminary longitudinal data suggest that THS may continue to accumulate in homes over time and household smoking bans may be protective. However, for homes with high occupant smoking levels, banning indoor smoking may not be fully adequate to protect children from THS. Unless smoking is reduced and bans are implemented, medically fragile children will be exposed to the dangers of THS.