Hand- and Object-Mouthing of Rural Bangladeshi Children 3-18 Months Old

Abstract

Children are exposed to environmental contaminants by placing contaminated hands or objects in their mouths. We quantified hand- and object-mouthing frequencies of Bangladeshi children and determined if they differ from those of U.S. children to evaluate the appropriateness of applying U.S. exposure models in other socio-cultural contexts. We conducted a five-hour structured observation of the mouthing behaviors of 148 rural Bangladeshi children aged 3-18 months. We modeled mouthing frequencies using 2-parameter Weibull distributions to compare the modeled medians with those of U.S. children. In Bangladesh the median frequency of hand-mouthing was 37.3 contacts/h for children 3-6 months old, 34.4 contacts/h for children 6-12 months old, and 29.7 contacts/h for children 12-18 months old. The median frequency of object-mouthing was 23.1 contacts/h for children 3-6 months old, 29.6 contacts/h for children 6-12 months old, and 15.2 contacts/h for children 12-18 months old. At all ages both hand- and object-mouthing frequencies were higher than those of U.S. children. Mouthing frequencies were not associated with child location (indoor/outdoor). Using hand- and object-mouthing exposure models from U.S. and other high-income countries might not accurately estimate children's exposure to environmental contaminants via mouthing in low- and middle-income countries.

Keywords: Bangladesh; child behavior; exposure factors; mouthing; non-dietary ingestion; rural.

Figure A1

Comparison of normal, lognormal, and Weibull distributions against observed data.

Figure 1

Schematic of structured observation method, including object super-category designation.

Figure 2

Observed hand- and object-mouthing frequencies by age group. Hands and objects are shaded for comparison across age groups. Objects include both cloth and non-cloth items.

Figure 3

Cumulative distribution function for hand- and object-mouthing data by location and age group, for children from Bangladesh and the U.S. [11,12]. The Bangladeshi distribution is based on inside and outside frequencies combined. The U.S. distributions are separated by location; for some age groups the outside mouthing frequency distribution has not been determined. The oldest age group is 12–18 months for Bangladeshi children and 12–24 months for U.S. children.