Mouthing behavior in infants and young children <3 years old is a poorly quantified yet normal part of early childhood development. Increasingly, safety and risk assessments involving materials that may be mouthed depend on accurate estimates of oral contact time. This study reports the results of an observational study performed to investigate and obtain data on mouthing behavior of objects for children up to 3 years old.


The study used a standard diary form with instructions for participating parents to observe their child in a normal environment (primarily home), and to document both the type and duration of each item mouthed. Phase I (pilot) consisted of 30 children each observed for 1 day, divided equally between the ages of 0 to 18 months (n = 15) and 19 to 36 months (n = 15), whereas Phase II included more participants (n = 92 aged 0–18 months;n = 95 aged 19–36 months). Phase III included observations for 5 nonconsecutive days over a 2-month period on 168 children between the ages of 3 to 18 months (at study initiation), and focused on total mouthing time of objects, exclusive of pacifiers.


The data collected during the first 2 phases were pooled and analyzed together. For all participants between the ages of 0 and 18 months (n = 107), the average daily duration of mouthing objects included: pacifiers (108 minutes), plastic toys (17 minutes), teethers (6 minutes), and other objects (9 minutes). The results for children 19 to 36 months old (n = 110) included: pacifiers (126 minutes), plastic toys (2 minutes), teethers (0 minutes), and other objects (2 minutes). Although no significant difference existed between the 2 age ranges for pacifier mouthing duration, a statistically significant difference was observed for nonpacifier objects. For Phase III, the average daily mouthing time for all objects (excluding pacifiers), based on 5 nonconsecutive days of observation for 168 children, was 36 minutes (n= 793 valid child observation days).


Results of this study indicate that mouthing behavior is dependent on age and the types of items that are mouthed. Duration of mouthing varies among children, with some consistently not mouthing any objects and with a very small number mouthing objects for >2 hours a day. The study also revealed wide variability in the types of objects mouthed, including many nontoy objects. Children mouth pacifiers significantly longer than other objects, regardless of age. Significantly increased mouthing time of all nonpacifier objects is reported for children in the 0- to 18-month range compared with the 19- to 36-month range.

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