Detailed information on children's mouthing activities helps researchers assess children's exposure to toxicants via the non-dietary ingestion route (i.e., exposure resulting from contacts between the mouth and non-dietary objects such as fingers, toys, and dirt). For the analyses presented in this article, 38 children (20 female and 18 male) aged 1 to 6 years were videotaped for 2 hours each during natural play primarily in the outdoor residential environment.

The data were analyzed separately by location (i.e., indoor or outdoor). For each location, mouthing frequency, contact duration, and hourly duration data were analyzed along gender and ≤ 24 months > 24 months age groupings. Several significant differences were found for mouthing activities occurring outdoors. Children ≤ 24 months of age were found to have significantly longer contact durations with the hands than children > 24 months of age (p = 0.04). Furthermore, for all ages, frequencies of mouthing contacts with the hands and non-dietary objects were significantly higher for girls than boys (p = 0.01 and p = 0.008, respectively). Girls also had significantly shorter hand-to-mouth contact durations than boys (p = 0.04). Although not statistically significant, mouthing frequencies with hands and non-dietary objects were higher indoors than outdoors while contact durations were similar between the two locations.