Background Children are susceptible to harmful substances found in indoor dust through frequent hand-to-mouth and object-to-mouth contacts. Despite the importance of this exposure route, few studies have quantified the frequency, duration, or patterns of mouthing behaviors in indoor residential settings, creating uncertainty in exposure and risk models. Objective This study quantified the frequency and duration of indoor mouthing contacts for children 6 months to 6 years across sociodemographic variables including age, sex, ethnicity, race and geographic region using advanced videotaping and video translation methodologies. Methods Ninety-nine children were videotaped for 3–4 h during natural indoor play across three U.S. regions (Arizona, Florida, and North Carolina). 360-degree cameras were mounted in different rooms to capture natural behavior without researcher presence. Footage was tracked and merged sequentially, then translated into Micro-Level Activity Time Series (MLATS) using the Virtual Timing Device (VTD), documenting each mouthing contact with specific surfaces and household locations to generate frequency (contacts/h) and duration (minutes/h) data. Results Mouthing duration showed significant age-related differences (Kruskal–Wallis χ 2 = 12.0, p = 0.007), with median duration declining from 18.67 min/h in children 6–12 months to 5.02 min/h in children 3–6 years. Four surfaces accounted for the majority of mouthing duration: “other food” (4.25%), “pacifiers” (3.91%), “food containers” (3.41%), and “hands” (2.92%). Pacifier use showed complete discontinuation by age 3–6 years ( p = 0.008). No significant differences in total mouthing duration or frequency were observed across sex, race, ethnicity, or geographic region, suggesting that age-stratified exposure factors may be sufficient without additional demographic stratification. Conclusion This study provides age-specific mouthing contact data to improve children’s exposure and risk estimates. The finding that duration decreases significantly with age while frequency remains stable suggests that exposure models should incorporate both parameters. The 360-degree camera methodology reduced observer interference while capturing comprehensive behavioral data across household microenvironments.
Adelabu et al. (Tue,) studied this question.