This study examined the influences of infants' age for the first use of smart devices and the amount of time to use them on the externalizing problem behavior as well as investigated whether maternal managing behavior (setting rules on accessing smart devices and monitoring their child's use of smart devices) had moderating effects. The study participants consisted of 521 three to six year old infants (235 boys and 286 girls). The data were analyzed by means of descriptive statistics and a hierarchical regression. The results of this study indicated that the age at first use of smart devices and maternal managing behavior had significant effects on the externalizing problem behavior of infants. The earlier the infants first used smart devices, the higher the level of externalizing problem behavior.Externalizing problem behavior was also found to be higher when the mothers showed no managing behavior.Second, maternal managing behavior moderated the relation between the age at first use of smart devices and the externalizing problem behavior of infants. The effects of the age at first use of smart devices on the externalizing problem behavior of infants were greater when the mothers did not set rules regarding the use of smart devices and did not supervise children when using smart devices.

In this study, the management polices of micropollutants (MPs) were reviewed and the future management strategy was discussed considering climate change and etc. In Korea, the investigation of drinking water has been actively carried out for the priority contaminants as well as MPs. Recently river and lake waters have been also examined for MPs. However, the coverage and depth of the investigation is limited. Moreover, climate change is likely to increase air & water temperature and it will affect the hydrological cycle. Such changes may increase the residual concentrations of MPs in water system. As water reuse increases, the residual MPs of the recycled water may create public concerns. Thus, in a viewpoint of the precautionary principle, more stringent management of MPs is recommended for the drinking water and the body-contact water use. For the surface water, more studies are necessary to understand the ecological risk by MPs.

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