Levels of Toxic and Essential Elements and Associated Factors in the Hair of Japanese Young Children.

There is growing concern regarding the effects of toxic element exposure on the development of children. However, little is known about the level of toxic elements exposure in Japanese children. The purpose of this study was to assess the concentrations of multiple elements (aluminum, cadmium, lead, calcium, copper, iron, magnesium, sodium, zinc) in the hair of 118 Japanese young children and to explore the factors associated with their element levels. The element concentration was analyzed by ICP-MS, and children's food and water intake were assessed by the questionnaire. Results showed that there were no large differences between the level of elements in the hair of Japanese children and those of children in other developed countries. Girls had significantly higher levels of aluminum, copper, and iron (p = 0.000, 0.014, and 0.013, respectively), and boys had a higher level of sodium (p = 0.006). The levels of calcium, iron, magnesium, and sodium in nursery school children were significantly higher than those in kindergarten children (p = 0.024, 0.001, 0.046, and 0.029, respectively). Multiple regression analyses with controlling the confounding variables showed significant negative associations of frequency of yogurt intake with aluminum and lead levels (p = 0.015 and 0.037, respectively). When the children were divided into three groups based on the frequency of yoghurt consumption, viz. L (≤once a week), M (2 or 3 times a week), and H (≥4 to 6 times a week) group, the mean aluminum concentration (µg/g) in the L, M, and H groups was 11.06, 10.13, and 6.85, while the mean lead concentration (µg/g) was 1.76, 1.70, and 0.87, respectively. Our results suggested the validity of hair element concentrations as an exposure measure of essential elements and frequent yogurt intake as a viable measure for protecting children from toxic elements. However, these findings will need to be confirmed in more detailed studies with larger sample sizes in the future.

Children's Hair Mercury Concentrations and Seafood Consumption in Five Regions of Japan.

Exposure to methylmercury (MeHg) during the foetal and postnatal periods is known to have adverse effects on children's development. However, little attention has been paid to MeHg exposure during early childhood in Japan. To examine the regional differences in MeHg exposure and seafood consumption and the association between MeHg exposure and seafood consumption and dental metal restorations, we measured the total mercury (T-Hg) concentration in hair as an MeHg exposure index, and using questionnaires, we measured the frequency and amount of seafood consumption and the presence of dental metal restorations in 118 children aged 3-6 years in five regions of Japan. The arithmetic and geometric means of the T-Hg concentrations in hair were 1.03 and 0.87 ppm, respectively, and approximately 40% of the children exceeded the United States Environmental Protection Agency recommendation of 1.0 ppm. Significant regional differences in the hair T-Hg concentrations were found among the five regions, and the regional differences were consistent with the traditional regional patterns of eating fatty fish. According to the regression analysis, the consumption of fatty fish, particularly tuna/swordfish, had a significant effect on hair T-Hg concentrations, whereas age, sex, the materials used for dental metal restorations, and other types of seafood or fish/shellfish had no significant effects.

Regional cerebral blood flow changes associated with emotions in children.

Combining a wireless telemetry system and a portable near-infrared instrument, we developed a movable optical spectroscopy system for monitoring cerebral hemodynamic changes. The patient carries a miniaturized near-infrared spectroscopy instrument on the back, and data are sent by a wireless telemetry system to a computer, without restricting patient movement. We used this system to detect hemodynamic changes associated with being startled, anticipation, and pleasant and unpleasant emotions in the bilateral prefrontal cortices of 16 right-handed 4- to 6-year-old preschool children while they were watching a 21-minute video clip consisting of various scenes that elicited emotional responses, interpolated with neutral scenes for comparison. The children were relaxed and cooperative when they were studied. Anticipation was associated with increases in cerebral blood flow in the left prefrontal cortex of the 6-year-old children, and unpleasant emotion was associated with decreases in cerebral blood flow bilaterally compared with neutral emotion, irrespective of age. No hemodynamic changes associated with the startle response were observed. Although this study should be considered preliminary, it is suggested that the emotional response is age-dependent and that the left prefrontal cortex participates in anticipation. Our newly developed system will open a window into brain physiology in children.