OBJECTIVESIt is crucial to consider covariates relevant for outcome variables in developing dose-effect relations of environmental hazardous toxins. The aim of this study was to clarify the covariates affecting hand tremor and postural sway in children.

METHODSHand tremor and postural sway, as well as hair mercury concentrations, were measured in 155 boys and 148 girls at age 7 years.

RESULTSCurrent mercury concentrations in child hair ranged from 0.35 to 6.32 μg/g (geometric mean, 1.71 μg/g for boys and 1.58 μg/g for girls), and were not significantly correlated with the neuromotor parameters. All hand tremor and postural sway parameters, except for tremor intensity at 1-6 Hz with non-dominant hand, were significantly larger in the boys than in the girls. Using multiple regression analysis, some postural sway parameters were related negatively to age in the boys and girls (p<0.05), and positively to height (p<0.05). Similarly, hand tremor parameters were positively related to age, height and heart rate either in the boys or in the girls (p<0.05). Also, there were positive relationships between tremor intensity at 1-6 Hz and transversal and sagittal sways at 1-2 Hz and 2-4 Hz (p<0.05).

CONCLUSIONSHeart rate and postural sway, together with age, sex, and height, should be considered in interpreting hand tremor in children. Hand tremor or postural sway may not be so sensitive or specific to methylmercury exposures at levels of less than 7 μg/g in hair.

OBJECTIVESExposure misclassification is a major obstacle to obtain accurate dose-response relationships. In order to solve this problem, the impact of hair treatment on total mercury in hair was assessed in Japanese women.

METHODSA cross-sectional study was carried out among 327 women at age 24-49 years to determine hair mercury levels and estimate daily mercury intakes from seafood by using a food frequency questionnaire.

RESULTSHair mercury levels in the women and daily mercury intake ranged from 0.11 to 6.86 (median 1.63) μg/g and from 0.77 to 144.9 (median 15.0) μg/day, respectively. The hair mercury was positively correlated with the daily mercury intake (p<0.001). When the women were divided into two subgroups based on artificial hair-waving, hair coloring/dyeing, residence (non-fishing and fishing areas), and working status, a significant difference in the hair mercury level was observed between the women with and without artificial hair-waving only (p<0.001). The multiple regression analysis showed that the log-transformed hair mercury level was significantly related to the log-transformed daily mercury intake (standardized regression coefficient βs=0.307) and artificial hair-waving (βs=-0.276); but not to hair coloring/dyeing, residence, working status or age. Permanent hair treatment was estimated to reduce total mercury in hair by approximately 30%, after adjusting for daily mercury intake and other possible factors.

CONCLUSIONSThese findings suggest that hair mercury is not the best biomarker of methylmercury exposure when a study population includes women with artificial hair-waving.

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 and 5.42 (3.89-7.59) ng g, 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 and 9.96 (7.05-13.8) ng g, 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.
Adult ; Female ; Fetal Blood ; chemistry ; Humans ; Japan ; Maternal Exposure ; statistics & numerical data ; Maternal-Fetal Exchange ; Metals ; blood ; Placenta ; chemistry ; Pregnancy ; blood ; Trace Elements ; blood ; Urban Health

BACKGROUND: Low-dose exposure to organophosphate (OP) insecticides during pregnancy may adversely affect neurodevelopment in children. To evaluate the OP exposure levels, single urine sampling is commonly adopted to measure the levels of dialkylphosphates (DAPs), common OP metabolites. However, the inter-day variations of urinary DAP concentrations within subjects are supposed to be large due to the short biological half-lives of the metabolites, and it is thus considered difficult to accurately assess OP exposure during pregnancy with single sampling. This study aimed to assess intra-individual variations of DAP concentrations and the reproducibility of the exposure dose categorization of OPs according to DAP concentration ranges in pregnant women in Japan. METHODS: Urine samples were collected from 62 non-smoking pregnant women (12-22 weeks of gestation) living in Aichi Prefecture, Japan. First morning void (FMV) and spot urine samples taken between lunch and dinner on the same day were collected on five different days during 2 weeks. The concentrations of DAP and creatinine in urine samples were measured using an ultra performance liquid chromatography with tandem mass spectrometry. Creatinine-adjusted and unadjusted concentrations were used for the intraclass correlation coefficient (ICC) calculations and surrogate category analyses. RESULTS: For all DAP metabolites, the creatinine-adjusted single ICCs exceeded 0.4, indicating moderate reliability. Overall, ICCs of spot urine samples taken in the afternoon were better than those taken as FMV. Surrogate category analyses showed that participants were categorized accurately into four exposure dose groups according to the quartile points. CONCLUSION This study indicated that a single urine sample taken in the afternoon may be useful in assessing OP exposure as long as the exposure is categorized into quartiles when conducting epidemiological studies in early to mid-pregnant women in Japan.
Adult ; Chromatography, Liquid ; Creatinine ; urine ; Environmental Exposure ; analysis ; Environmental Monitoring ; methods ; Environmental Pollutants ; urine ; Female ; Humans ; Japan ; Mass Spectrometry ; Organophosphates ; urine ; Pesticides ; urine ; Pregnancy ; Pregnant Women ; Young Adult

BACKGROUND: To examine changes in psychological distress prevalence among pregnant women in Miyagi Prefecture, which was directly affected by the Great East Japan Earthquake and tsunami, and compare it with the other, less damaged areas of Japan. METHODS: This study was conducted in conjunction with the Japan Environment and Children`s Study. We examined 76,152 pregnant women including 8270 in Miyagi Regional Center and 67,882 in 13 other regional centers from the all-birth fixed data of the Japan Environment and Children's Study. We then compared the prevalence and risk of distress in women in Miyagi Regional Center and women in the 13 regional centers for 3 years after the disaster. RESULTS: Women in the Miyagi Regional Center suffered more psychological distress than those in the 13 regional centers: OR 1.38 (95% CI, 1.03-1.87) to 1.92 (95% CI, 1.42-2.60). Additionally, women in the inland area had a consistently higher prevalence of psychological distress compared to those from the 13 regional centers: OR 1.67 (95% CI, 1.18-2.38) to 2.19 (95% CI, 1.60-2.99). CONCLUSIONS The lack of pre-disaster data in the Japan Environment and Children's Study made it impossible to compare the incidence of psychological distress before and after the March 2011 Great East Japan Earthquake. However, 3 years after the Great East Japan Earthquake, the prevalence of pregnant women with psychological distress did not improve in Miyagi Regional Center. Further, the prevalence of mental illness in inland areas was consistently higher than that in the 13 regional centers after the disaster.
Adolescent ; Adult ; Disasters ; Earthquakes ; Female ; Humans ; Japan/epidemiology* ; Pregnancy ; Pregnancy Complications/psychology* ; Pregnant Women/psychology* ; Prevalence ; Psychological Distress ; Tsunamis ; Young Adult