Association between being Overweight in Young Childhood and during School Age and Puberty.

To examine whether body type at birth, body weight, and obesity in early childhood are associated with overweight/obesity during school age and puberty. Data from maternal and child health handbooks, baby health checkup information, and school physical examination information of participants at birth and three-generation cohort studies were linked. Association between body type and body weight at different time intervals (at birth and at 1.5, 3.5, 6, 11, and 14 years of age) were comprehensively analyzed using a multivariate regression model adjusted for gender, maternal age at childbirth, maternal parity, and maternal body mass index, and drinking and smoking statuses at pregnancy confirmation. Children who are overweight in young childhood had a greater risk of being overweight. Particularly, overweight at one year of age during checkup was associated with overweight at 3.5 years (adjusted odds ratio (aOR), 13.42; 95% confidence interval (CI), 4.46-45.42), 6 years (aOR, 6.94; 95% CI, 1.64-33.46), and 11 years (aOR, 5.22; 95% CI, 1.25-24.79) of age. Therefore, being overweight in young childhood could increase the risk of being overweight and obese during school age and puberty. Early intervention in young childhood may be warranted to prevent obesity during school age and puberty.

Exposure profile of mercury, lead, cadmium, arsenic, antimony, copper, selenium and zinc in maternal blood, cord blood and placenta: the Tohoku Study of Child Development in Japan.

BACKGROUND: The effects of prenatal exposure to toxic elements on birth outcomes and child development have been an area of concern. This study aimed to assess the profile of prenatal exposure to toxic elements, arsenic (As), bismuth (Bi), cadmium (Cd), mercury (total mercury (THg), methylmercury (MHg), inorganic mercury (IHg)), lead (Pb), antimony (Sb) and tin (Sn), and essential trace elements, copper (Cu), selenium (Se) and zinc (Zn), using the maternal blood, cord blood and placenta in the Tohoku Study of Child Development of Japan (N = 594-650). METHODS: Inductively coupled plasma mass spectrometry was used to determine the concentrations of these elements (except mercury). Levels of THg and MeHg were measured using cold vapour atomic absorption spectrophotometry and a gas chromatograph-electron capture detector, respectively. RESULTS: Median concentrations (25th-75th) of As, Cd, Pb, Sb, Sn and THg in the maternal blood were 4.06 (2.68-6.81), 1.18 (0.74-1.79), 10.8 (8.65-13.5), 0.2 (0.06-0.40) and 0.2 (0.1-0.38) ng mL-1 and 5.42 (3.89-7.59) ng g-1, respectively. Median concentrations (25th-75th) of As, Cd, Pb, Sb, Sn and THg in the cord blood were 3.68 (2.58-5.25), 0.53 (0.10-1.25), 9.89 (8.02-12.5), 0.39 (0.06-0.92) and 0.2 (0.2-0.38) ng mL-1 and 9.96 (7.05-13.8) ng g-1, respectively. CONCLUSIONS: THg and Sb levels in the cord blood were twofold higher than those in the maternal blood. Cord blood to maternal blood ratios for As, Cd and Sb widely varied between individuals. To understand the effects of prenatal exposure, further research regarding the variations of placental transfer of elements is necessary.

Effects of intrauterine exposures to polychlorinated biphenyls, methylmercury, and lead on birth weight in Japanese male and female newborns.

BACKGROUND: The effects of prenatal exposures to polychlorinated biphenyls (PCBs), methylmercury, and lead on birth weight remain disputable. The aim of this study was to investigate whether these chemicals affect birth weight of Japanese newborns, with special emphasis on determining whether these effects differ between males and females. METHODS: The subjects from Tohoku Study of Child Development, which was designed to examine the developmental effects of prenatal exposures to such hazardous chemicals, were 489 mother-newborn pairs with complete data including smoking habit during pregnancy. RESULTS: The mean birth weight of all newborns was 3083 (range, 2412-4240) g. The median values of biomarkers in cord blood were 46.0 (5th and 95th percentiles, 18.6-113.8) ng/g-lipid for total PCBs, 10.1 (4.3-22.4) ng/g for total mercury (THg), and 1.0 (0.6-1.7) µg/dL for lead. The birth weight was significantly heavier in the 252 male newborns than in the 237 female ones. A negative association between total PCBs and birth weight was observed in both male and female newborns, even after adjusting for possible confounders. However, a negative association of THg with birth weight was found only in the male newborns. There was no significant relationship between lead and birth weight in both groups. CONCLUSION: Birth weight appears to be affected by prenatal PCB exposure in Japanese male and female newborns, and the effect of methylmercury exposure on male fetal growth may be stronger than that for females. This implication is that the effects on fetal growth should be assessed in males and females separately.

Impacts of prenatal exposures to polychlorinated biphenyls, methylmercury, and lead on intellectual ability of 42-month-old children in Japan.

BACKGROUND: The age-specific impacts of perinatal exposures to polychlorinated biphenyls (PCB), methylmercury (MeHg), and lead on child neurodevelopment remain controversial. Since we have already reported the prenatal effects of these chemicals on neurodevelopment in 3-day-old and 30-month-old children of a birth cohort, the following effects were analyzed in the 42-month-old children in the same cohort. METHODS: The Kaufman Assessment Battery for Children (K-ABC), comprised of four scales, was used to assess their intelligence and achievement. The relationships between the chemicals and K-ABC scores were analyzed using multivariate analyses. RESULTS: The median values of chemicals in cord blood of 387 children were 46.5 (5th and 95th percentiles, 16.7-115.7)ng/g-lipid for total PCB, 10.1 (4.3-22.2)ng/g for total mercury (THg), and 1.0 (0.5-1.8) µg/dL for lead. Of the highly chlorinated PCB homologs, 9 CBs was negatively correlated with the sequential and mental processing score of the K-ABC (p<0.05). There were no significant correlations between any K-ABC score and either THg or lead. The negative effect of 9 CBs remained even after adjusting for THg, lead, and other confounders. The K-ABC scores were significantly lower in the boys than in the girls, and the standardized ß of 9 CBs for the sequential and mental processing scores in multiple regression analysis was statistically significant in boys. CONCLUSIONS: These findings suggest that intellectual ability in the developmental stage may be impaired by prenatal exposures to highly chlorinated PCB homologs, especially in Japanese boys.

[Normative study of the Boston naming test in 7-year-old Japanese children].

OBJECTIVES: The Boston Naming Test (BNT) has been used to assess the language development of children in many epidemiology studies, and its usefulness is confirmed. The BNT consists of 60 black and white line drawings of objects and animals. There are no normative data available for this test for Japanese children. The purpose of this study was to collect normative information in Japan and to examine the correlation between the score of the BNT and Intelligence Quotient (IQ) of the Wechsler Intelligence Scale for Children third edition (WISC-III). METHODS: The BNT was translated into Japanese and administered in children registered to the birth cohort of the Tohoku Study of Child Development at the age of 84 months. The participants for analysis in this study were 449 children (237 boys, 212 girls). RESULTS: There were four items with percentage scores below 1%; Igloo, Knocker, Muzzle, and Yoke. Many Japanese children could answer 'abacus' and 'compass', which are difficult for US children. Although the score of the BNT correlated with IQ of the WISC-III (p<0.001), as compared with the previous studies, the correlation coefficient was low. CONCLUSIONS: The BNT is quick and easy to use and valuable for researchers in evaluating language ability in children. Since the BNT was developed in the United States, the cultural values of that country are reflected in the BNT score. This implies that the BNT should be modified to fit Japanese population.

Increase in accumulation of polychlorinated biphenyls in offspring mouse brain via maternal coexposure to methylmercury and polychlorinated biphenyls.

Methylmercury (MeHg) and polychlorinated biphenyls (PCBs) are environmentally persistent neurodevelopmental toxicants. In Japan, the most common source of human exposure is the consumption of contaminated fish and seafood. We investigated the accumulation of MeHg and PCBs in the brains of dams and offspring mice maternally exposed to MeHg and/or PCBs. Pregnant mice (C57BL/6Cr) were assigned to one of four exposure groups: control, MeHg alone (MeHg in diet at 5 mg/kg as Hg), PCB alone (Aroclor1254 by gavage at the dose of 18 mg/kg body weight/3 days) and MeHg+PCB. Levels of MeHg and PCBs were measured in the whole brains of dams and offspring mice on postnatal day 21 (PND21) and at 9 weeks of age. Total mercury, MeHg and PCB congener concentrations were determined by CVAAS, GC-ECD and HRGC/HRMS, respectively. For the mercury concentrations, there were no significant differences between MeHg alone and MeHg+PCB except for pups at 9 weeks. The maternal PCB levels were not significantly different between MeHg+PCB and PCB alone. In pup brain on PND21, MeHg+PCB resulted in a significantly higher PCB level than PCB alone. Although the levels of lightly chlorinated (= 4CBs) homologues were lower for MeHg+PCB than for PCB alone, those of highly chlorinated (>= 5CBs) homologues were significantly higher on PND21 for MeHg+PCB. The PCB composition in dams and pups shifted to higher chlorinated homologues compared with the composition of administered Aroclor1254. For these reasons, further detailed studies are necessary to clarify the interactional effects of PCB metabolism after coexposure to MeHg and PCBs.

Breastfeeding leads to lower blood pressure in 7-year-old Japanese children: Tohoku Study of Child Development.

This study investigated the association between breastfeeding and both self-measured home blood pressure (HBP) and conventional blood pressure (CBP) in 7-year-old Japanese children. We obtained data pertaining to breastfeeding and blood pressure for 377 mother-offspring pairs from the Tohoku Study of Child Development, which is a prospective birth cohort study. Information on breastfeeding and other factors were obtained from parental questionnaires during the follow-up period. Based on the duration of breastfeeding as a major source of nutrition, mother-offspring pairs were divided into short-term (mean, 5.1 months) and long-term (mean, 11.3 months) breastfeeding groups. At the age of 7 years (84.4±1.8 months), each child's blood pressure was measured. The HBP in the long-term breastfeeding (LBF) group (92.9 mm Hg systolic/55.1 mm Hg diastolic) was significantly lower (P=0.006/0.04) than in the short-term breastfeeding group (94.7/56.4 mm Hg); however, there were no significant differences in the CBP measurements between the short- and LBF groups. Using multiple regression analysis, the duration of breastfeeding (greater than 8 months) was more strongly associated with HBP (P=0.008/0.05) than with CBP (P=0.4/0.9). Furthermore, the adjusted R-squared values for HBP (0.25/0.12) tended to be higher than those for CBP (0.07/0.03). These findings were independent of the birth weight. In conclusion, breastfeeding has a protective effect against elevated blood pressure even in young children, and subtle, but important, differences were precisely detected by self-measurements performed at home.

Mother-offspring aggregation in home versus conventional blood pressure in the Tohoku Study of Child Development (TSCD).

OBJECTIVE: Few studies described the home blood pressure (HBP) in young children. Using intrafamilial correlations of blood pressure as research focus, we assessed the feasibility of HBP monitoring in this age group. METHODS: We enrolled 382 mothers (mean age 38.8 years) and singletons (7.0 years) in theTohoku Study of Child Development.We measured their conventional blood pressure (CBP; single reading) at an examination centre. Participants monitored HBP in the morning. We used the OMRON HEM-70801C for CBP and HBP measurement. In a separate group of 84 children (mean age 7.7 years), we compared blood pressure readings obtained by the OMRON monitor and the Dinamap Pro 100, a device approved by FDA for use in children. We used correlation coefficients as measure of intrafamilial aggregation, while accounting for the mothers' age, body mass index, heart rate and smoking and drinking habits and the children's age, height, and heart rate. RESULTS: Mother-offspring correlations were closer (P < or = 0.003) for HBP than CBP for systolic pressure [0.28 (P < 0.0001) vs 0.06 (P = 0.26)] and diastolic pressure [0.28 (P < 0.0001) vs 0.02 (P = 0.65)].The between-device differences (OMRON minus Dinamap) averaged 7.8 +/- 6.0 mmHg systolic and 5.8 +/- 5.5 mmHg diastolic. CONCLUSIONS: HBP monitoring is an easily applicable method to assess intrafamilial blood pressure aggregation in young children and outperforms CBP. Validation protocols for HBP devices in young children need revision, because the Korotkoff method is not practicable at this age and there is no agreed alternative reference method.

Prenatal exposures to environmental chemicals and birth order as risk factors for child behavior problems.

OBJECTIVES: To assess whether polychlorinated biphenyls (PCBs), methylmercury, lead, or parental child-rearing attitudes was most crucial for maladaptive behavior problems, we examined Japanese 30-month-old children followed up from pregnancy. METHODS: The Child Behavior Checklist (CBCL) was used to assess the behavior problems in 306 children. The associations of cord-blood total PCBs (ΣPCB), total mercury (THg), and lead with each CBCL subscale were examined by multivariate analyses. RESULTS: The median values in cord blood of the 306 children were 48.3 (5 and 95 percentiles, 18.6-116.3) ng/g-lipid for ΣPCB, 10.2 (4.1-24.5)ng/g for THg, and 1.0 (0.5-1.7)µg/dl for lead. The internalizing score of the CBCL was significantly correlated with ΣPCB (r=0.113) in the children, though no significant correlation was seen between any CBCL score and either THg or lead. The significant correlation disappeared when conducting multiple regression analysis with possible confounders; at that time, the birth order, home environment, and maternal intelligence quotient were significantly related to the internalizing score. Three CBCL scores and ΣPCB levels were significantly higher in the first-born children than in the second-born or following children, and the partial correlation coefficient with the adjustment for all confounders except birth order was significant between the internalizing score and ΣPCB in the latter children (r=0.175). CONCLUSIONS: Internalizing behavior appears to be affected by prenatal exposure to PCBs at low levels. Under lower-level exposures, however, behavior problems may be more strongly associated with parental child-rearing attitudes involved in birth order, than with such hazardous chemicals.

Hair-to-blood ratio and biological half-life of mercury: experimental study of methylmercury exposure through fish consumption in humans.

The hair-to-blood ratio and biological half-life of methylmercury in a one-compartment model seem to differ between past and recent studies. To reevaluate them, 27 healthy volunteers were exposed to methylmercury at the provisional tolerable weekly intake (3.4 µg/kg body weight/week) for adults through fish consumption for 14 weeks, followed by a 15-week washout period after the cessation of exposure. Blood was collected every 1 or 2 weeks, and hair was cut every 4 weeks. Total mercury (T-Hg) concentrations were analyzed in blood and hair. The T-Hg levels of blood and hair changed with time (p < 0.001). The mean concentrations increased from 6.7 ng/g at week 0 to 26.9 ng/g at week 14 in blood, and from 2.3 to 8.8 µg/g in hair. The mean hair-to-blood ratio after the adjustment for the time lag from blood to hair was 344 ± 54 (S.D.) for the entire period. The half-lives of T-Hg were calculated from raw data to be 94 ± 23 days for blood and 102 ± 31 days for hair, but the half-lives recalculated after subtracting the background levels from the raw data were 57 ± 18 and 64 ± 22 days, respectively. In conclusion, the hair-to-blood ratio of methylmercury, based on past studies, appears to be underestimated in light of recent studies. The crude half-life may be preferred rather than the recalculated one because of the practicability and uncertainties of the background level, though the latter half-life may approximate the conventional one.

[Association of BMI with the beta3 adrenergic receptor gene mutation: a meta-analysis].

The beta3 adrenergic receptor (ADRB3) is a part of the adrenergic system, which is known to play a key role in energy metabolism. The relationship between the Trp64Arg variant of ADRB3 and body mass index (BMI) has been widely examined; however, the results of these studies have been inconsistent. Therefore, we performed a meta-analysis of the relationship between an ADRB3 variant and BMI in 2008. Our results suggested that the Trp64Arg variant of ADRB3 was associated with BMI in East Asians, but not Europeans. Additionally, our report showed the importance of meta-analyses in the field of genetic association studies for common traits. In 1995, Yoshida et al. reported that the Trp64Arg variant of ADRB3 was related to difficulty in weight loss. The decrease in body weight in obese subjects with the mutation was lower than that in obese subjects without the mutation following a 3 month combined low-calorie diet and exercise regimen. However, subsequent studies have yielded inconsistent results. Accordingly, further studies are needed to reliably assess and interpret gene-phenotype associations with this ADRB3 variant.

[Comparison of long-chain polyunsaturated fatty acids in plasma and erythrocyte phospholipids for biological monitoring].

OBJECTIVES: Previous data have indicated that the erythrocyte membrane may be the preferred sample type for assessing long-chain polyunsaturated fatty acid (LCPUFA) contents in cardiac and cerebral membranes. In this epidemiological study, we examined whether plasma phospholipids can be used for accurate biological monitoring of the LCPUFA state or whether analysis of erythrocyte membrane phospholipids is indispensable. METHODS: (1) The analysis of LCPUFA contents in erythrocyte membrane phospholipids was conducted at baseline and after 1 and 3 days at 4°C, and 21 days at -40°C, after blood drawing, and the changes in LCPUFA content were examined. (2) The LCPUFA compositions of plasma and erythrocyte phospholipids in 133 young women (18-30 years old) were examined and the relationships between the sample type and the levels of LCPUFAs were determined. RESULTS: Eicosapentaenoic acid (EPA), docosahexaenoic acid (DHA) and DHA/arachidonic acid (AA) and (EPA+DHA)/AA ratios in erythrocyte membrane phospholipids after 21 days of blood drawing significantly decreased compared with the corresponding baseline data. Regarding AA, EPA and DHA, a significant positive correlation was shown between levels of erythrocyte membrane phospholipids and plasma phospholipids (AA, r=0.364; EPA, r=0.709; DHA, r=0.653). The predictive value of plasma phospholipids for determining the highest concentration quartile in erythrocyte phospholipids was better in EPA (70%) than in DHA (55%) and AA (42%). CONCLUSIONS: The measurement of LCPUFA content in erythrocyte membrane phospholipids is necessary for accurate biological monitoring. We also found that LCPUFA in erythrocyte membrane phospholipids is stable in cold storage (4°C) for 3 days after blood drawing.

Recent trends of body mass index distribution among school children in Sendai, Japan: Decrease of the prevalence of overweight and obesity, 2003-2009.

SUMMARY: It was reported that the number of obese children increased during the final decades of the 20th century. However, it is unclear whether the prevalence of obesity has changed in recent years. The aim of this study was to examine trends in the body mass index (BMI) and prevalence of obesity in 6th grade primary school children (6thPS) and 3rd year junior high school students (3rdJHS) in Sendai, Japan between 2003 and 2009. BMI (kg/m(2)) was calculated and the prevalences of overweight and obesity were defined based on internationally agreed cutoff points. The mean BMI significantly decreased during the study period in all groups. In addition, the results of regression analysis revealed that significant decreases in BMI occurred in all percentiles in all groups as well. The mean prevalence rates of overweight and obese children as defined by international reference values during the observation period were 19.5% and 4.1% for boys in 6thPS, 13.6% and 2.2% for girls in 6thPS, 13.6% and 3.0% for boys in 3rdJHS and 12.2% and 1.9% for girls in 3rdJHS, respectively. There was a significant decreasing trend in the proportion of overweight and obese children from 2003 to 2009. The downward shifts of BMI might be due to effect modification in the lifestyle of children. Since we had no further data for characterization of Sendai school children and the period of this observation was only 7 years, the reasons for the change in the prevalence of obesity in this population remain speculative.:

[Construction of Maladaptive Behavior Scale in Japanese].

OBJECTIVES: To evaluate child development, social competence, like intellectual ability, is an important aspect. The social competence of a child is prescribed by behaviors suitable for the society (adaptive behaviors) and behaviors not suitable for the society (maladaptive behaviors). The Vineland Adaptive Behavior Scales (VABS) have been widely administered to children in a semi-structural interview to evaluate social competence. The Social Competence test (S-M test) widely used in Japan is a translated version of the Vineland Social Maturity Scale for adaptive behaviors. Since only the region of adaptive behaviors was translated into Japanese, we attempted to develop a Maladaptive Behavior Scale in Japanese based on the VABS to evaluate the social competence of children. METHODS: The Maladaptive Behavior Scale of the VABS was translated into Japanese and back-translated to ensure appropriate translation. It was administered to children belonging to the birth cohort of the Tohoku Study of Child Development at the age of 66 months. The subjects for analysis in this study were 451 children (230 boys, 221 girls). RESULTS: To assess internal consistency, we used the standardized Cronbach alpha coefficient and the result was 0.81. The correlation coefficient between the scores of the S-M test and those of the Maladaptive Behavior Scale was -0.15. The correlation coefficient between the scores of the Child Behavior Checklist at 30 months and those of the Maladaptive Behavior Scale was 0.44. CONCLUSION: These results suggest that the Maladaptive Behavior Scale may be a reliable instrument for assessing maladaptive behavior in Japanese children.

Neurobehavioral effects of prenatal exposure to methylmercury and PCBs, and seafood intake: neonatal behavioral assessment scale results of Tohoku study of child development.

As factors affecting neonatal neurodevelopment, methylmercury, polychlorinated biphenyls (PCBs), and maternal seafood intake reflecting n-3 polyunsaturated fatty acids (PUFAs) are believed to have adverse or beneficial effects, but there are a few reports addressing such factors simultaneously. We carried out a birth cohort study to clarify the effects of these three factors on the Neonatal Behavioral Assessment Scale (NBAS), administered 3 days after birth. In a total of 498 mother-neonate pairs, the total mercury level (median, 1.96microg/g) in maternal hair at parturition and the summation operatorPCB level (45.5ng/g-lipid) in cord blood were analyzed, and maternal seafood intake was estimated using a semi-quantitative food frequency questionnaire. A negative relationship between the hair mercury level and the motor cluster of NBAS was observed, even after adjusting for PCBs, maternal seafood intake, and possible confounders such as maternal age, birth weight, and parity. The summation operatorPCB level was negatively correlated with the motor cluster, but this association was attenuated after adjusting for mercury and the confounders. There was seen to be a positive association between maternal seafood intake and the motor cluster when considering the effects of mercury and PCBs. In conclusion, our data suggest that prenatal exposure to methylmercury adversely affects neonatal neurobehavioral function; in contrast, maternal seafood intake appears to be beneficial. The neurobehavioral effect of prenatal exposure to PCBs remains unclear in our study. Further research is necessary to elucidate interactive effects of methylmercury, PCBs, and n-3 PUFAs, originating from fish, on child neurodevelopment.

Gene expression profiles in the brain of the neonate mouse perinatally exposed to methylmercury and/or polychlorinated biphenyls.

Methylmercury (MeHg) and polychlorinated biphenyls (PCBs) are environmentally persistent neurodevelopmental toxicants. The primary source of human exposure is the consumption of contaminated fish, seafood and marine mammals. However, little is known about the molecular mechanisms of MeHg and PCB toxicities and interactions between these contaminants. We investigated the functional profiles of differently expressed genes in the brains of offspring mice perinatally exposed to MeHg and/or PCBs to elucidate how these contaminants interact with each other. Pregnant mice (C57BL/6) were divided into four groups by exposure: (1) vehicle control, (2) MeHg alone, (3) PCBs alone, (4) MeHg + PCBs. Gene expression analysis of the brains of offspring mice was carried out with 4 x 44 K whole mouse genome's microarrays (Agilent) on postnatal day 1. The gene expression pattern of the MeHg exposure-group differed from that of the PCB-exposure group. The MeHg + PCB group expressed a larger number of genes, most of which were not expressed in the MeHg group or PCB group. It was revealed that gene expression was greatly increased, and the most altered genes were found with co-exposure. The genes were related to the functional categories of development, inflammation, calcium ion homeostasis, signal transduction, the ubiquitin-proteasome pathway and detoxication. The ubiquitin-proteasome system and detoxication categories might function for protection against the toxicity induced by co-exposure to MeHg and PCBs. These results suggest that co-exposure does not simply exacerbate the toxicity of MeHg alone or PCB alone, but stimulates a protection system.

Intervention study on cardiac autonomic nervous effects of methylmercury from seafood.

To scrutinize whether the provisional tolerable weekly intake (PTWI, 3.4 microg/kg body weight/week) of methylmercury in Japan is safe for adults, we conducted an intervention study using heart rate variability (HRV) that has been considered to reflect cardiac events. Fifty-four healthy volunteers were recruited and divided into experimental and control groups. The experimental group was exposed to methylmercury at the PTWI level through consumption of bigeye tuna and swordfish for 14 weeks, and HRV parameters were compared between the two groups. In the experimental group, mean hair mercury levels, determined before and after the dietary methylmercury exposure and after 15-week wash-out period following the cessation of exposure, were 2.30, 8.76 and 4.90 microg/g, respectively. The sympathovagal balance index of HRV was significantly elevated after the exposure, and decreased to the baseline level at the end of this study. Still, such changes in HRV parameters were not found in the control group with a mean hair mercury level of around 2.1 microg/g. In conclusion, the PTWI does not appear to be safe for adult health, because methylmercury exposure from fish consumption induced a temporary sympathodominant state. Rather, long-term exposure to methylmercury may pose a potential risk for cardiac events involving sympathovagal imbalance among fish-consuming populations.

Assessment of exposure to methylmercury in pregnant Japanese women by FFQ.

OBJECTIVE: To examine whether an FFQ can be used for assessing exposure to methylmercury (MeHg) by estimating MeHg intake from seafood consumption using the FFQ and confirming the accuracy of the estimated value. DESIGN: Seafood consumption of pregnant women was assessed using the FFQ. Total mercury (T-Hg) concentrations of maternal red blood cells (RBC) and hair were measured as exposure indices of MeHg. SETTING: A prospective birth cohort study, the Tohoku Study of Child Development (TSCD), which has been ongoing since 2001. SUBJECTS: The subjects were 609 pregnant Japanese women who were enrolled in the TSCD. RESULTS: MeHg intake was estimated from seafood consumption determined using the FFQ and the MeHg concentrations in each type of seafood. The accuracy of the estimated value was confirmed by comparison with T-Hg in RBC and hair. Estimated MeHg intake was 42.3 microg/week, and 43.0 % of that was from large predatory fish. Compared with the Japanese tolerable weekly intake, in total 12.5 % of the subjects exceeded it. T-Hg concentrations in RBC and hair were significantly correlated with estimated MeHg intake: r = 0.325 (P < 0.0001) for RBC and r = 0.305 (P < 0.0001) for hair. CONCLUSIONS: Estimated MeHg intake based on the FFQ was significantly associated with T-Hg concentrations in RBC and hair. Although the estimated value involves uncertainties, the FFQ appears to be a useful tool for assessment of exposure to MeHg.

Trends of body mass index distribution in schoolchildren in Sendai, Japan, 1989-2003.

SUMMARY: Accumulating evidence indicates a strong association between obesity and health problems. Childhood obesity increases the risk of adulthood obesity. Although it is reported that the number of obese children in Japan has increased, it is unclear whether the obesity index distribution pattern has changed. To clarify this distribution pattern, we analyzed the changes in the body mass index (BMI) of primary (6th grade, 12 years old) and junior high (3rd year, 15 years old) schoolchildren in the city of Sendai during the period from 1989 to 2003. Our department has accumulated information on the height and body weight of all the schoolchildren in the city of Sendai. BMI was calculated using both the height and body weight data. The change in median BMI for 15 years had a slightly upward trend every year with both gender and school year. Although the BMI distribution showed that there was little or no change over time in the lower (10th and 25th) percentiles, the increases in the 75th and 90th percentiles were more marked than that in the 50th percentile in primary school children. On the other hand, there was only a small increase in BMI in the 3rd year of junior high school. Our results indicated that the changes in BMI distribution were concentrated at the upper end of the distribution in primary school children. The shifts in the value of high percentiles might be due to effect modification of the corresponding exposure by another environmental exposure or genetic predisposition. It is suggested that the factors causing this change influenced only part of this population, and affected individuals might represent a susceptible subpopulation of the exposed children.:

Trends in growth status among schoolchildren in Sendai, Japan, 1994-2003: leveling-off of mean body height and weight.

Secular changes in growth have been well documented in various world populations, with secular increase especially noticeable in the developed countries. Accordingly, we have been monitoring the secular changes in growth status among the 6th year children in primary schools (6thPS, 11-12 years old) and 3rd year children in junior high schools (3rdJHS, 14-15 years old) in the city of Sendai since 1934. After World War II, both primary school children and junior high school students showed marked increases in height and weight up to the early 1970s. Acceleration and the subsequent reduction in the degree of acceleration in growth were observed in 1965-1974 and 1975-1984, respectively, and were followed by reacceleration in 1985-1994. The aim of this study was to assess the growth changes among Sendai schoolchildren in 1994-2003. The period between 1994 and 1999 was characterized by positive trends both in height and weight among schoolchildren. However, the degree of the increases in height and weight was diminished between 1999 and 2003. The linear regression analysis revealed the significant increases in mean weight during the 10-year study period in 6thPS boys and 3rdJHS boys and girls. In contrast, there was no significant increase in mean height in any group. These findings suggest the leveling-off of the mean body height and weight among schoolchildren in Sendai at the end of the 20th century. Additional study is needed to examine possible explanations and consequences of these secular trends.