Preliminary evidence that high levels of nicotine on children's hands may contribute to overall tobacco smoke exposure

Background Dust and surfaces are important sources of lead and pesticide exposure in young children. The purpose of this pilot study was to investigate if third-hand smoke (THS) pollutants accumulate on the hands of children who live in environments where tobacco is used and if hand nicotine levels are associated with second-hand smoke (SHS), as measured by salivary cotinine. Methods Participants were parents and children (n=25; age mean (SD)=5.4 (5.3) years) presenting to the emergency department with a potentially SHS-related illness. A convenience sample of participants were recruited at baseline from an ongoing two-group, randomised controlled trial of a SHS reduction and tobacco cessation intervention. Parents were current smokers; thus, all children were at risk of SHS and THS exposure to varying extents. Primary outcome measures, which were assessed in child participants only, were hand nicotine and salivary cotinine. Parents reported sociodemographics and smoking patterns; children's medical records were abstracted for chief complaint, medical history and discharge diagnosis. Results All children had detectable hand nicotine (range=18.3-690.9ng/wipe). All but one had detectable cotinine (range=1.2-28.8ng/mL). Multiple linear regression results showed a significant positive association between hand nicotine and cotinine (p=0.009; semipartial r(2)=0.24), independent of child age. Discussion The higher-than-expected nicotine levels and significant association with cotinine indicate that THS may play a role in the overall exposure of young children to tobacco smoke toxicants and that hand wipes could be a useful marker of overall tobacco smoke pollution and a proxy for exposure. Trial registration number ClinicalTrials.gov Identifier: NCT02531594