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Severe methylmercury poisoning occurred in Minamata and neighboring communities in Japan during the 1950s and 1960s, causing what is known as Minamata disease. Although an increase in stillbirths and a reduced male proportion at birth (i.e., reduced sex ratio) have been reported, no studies have evaluated the impact of exposure on an entire set of infant and birth outcomes. We therefore evaluated the temporal trends of these outcomes in the Minamata area from 1950 to 1974. We focused on the spontaneous/artificial stillbirth rate, crude fertility rate, male proportion at birth, male proportion among stillbirths, and infant mortality. We obtained the number of stillbirths, live births, and infant deaths in Minamata City and Kumamoto Prefecture (as a reference) from 1950 to 1974. After plotting annual figures for each outcome, we divided the study period into five intervals and compared them between Minamata City and Kumamoto Prefecture using the chi-squared test. We observed a slightly increased spontaneous stillbirth rate and decreased artificial stillbirth rate in Minamata City, followed by a reduced crude fertility rate. The crude fertility rates in Minamata City during the period 1955–1965 were significantly lower compared with those in Kumamoto Prefecture (p < 0.001). An increase in the male proportion among stillbirths was observed, corresponding to a reduction in the proportion of males at birth in the late 1950s. The impact on infant mortality was equivocal. These descriptive analyses demonstrate a severe regional impact of methylmercury exposure on a series of birth outcomes in the Minamata area. [ABSTRACT FROM AUTHOR]

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Background: Evidence linking air pollution with adverse health outcomes is accumulating. However, few studies have adopted a quasi-experimental design to evaluate whether decline in air pollution from regulatory action improves public health. We evaluated the effect of a diesel emission control ordinance introduced in 2003 on mortality rates in 23 wards of the Tokyo metropolitan area, Japan, from October 2000 to September 2012, taking into account change in mortality rates in a reference population (Osaka) with a introduction of such a regulation in 2009.Methods: We obtained daily counts of all-cause and cause-specific mortality and concentrations of nitrogen dioxide (NO2) and particulate matter less than 2.5 μm in diameter (PM2.5) during the study period. We employed interrupted time-series analysis to analyze the data.Results: Decline in NO2 during the study period was similar in the two areas, while decline in PM2.5 and the improvement in age-standardized mortality rates were greater in Tokyo's 23 wards compared with Osaka. Even after adjusting for age-standardized mortality rates in Osaka, percent changes in mortality between the first 3-year interval (October 2000 to September 2003) and the last 3-year interval (October 2009 to September 2012) were -6.0% for all causes, -11% for cardiovascular disease, -10% for ischemic heart disease, -6.2% for cerebrovascular disease, -22% for pulmonary disease, and -4.9% for lung cancer. We did not observe a decline in mortality from other causes.Conclusions: This quasi-experimental study in Tokyo suggests that emission control was associated with improvements in both air quality and health outcomes. [ABSTRACT FROM AUTHOR]

Background: Recent studies suggest that prenatal exposure to outdoor air pollution is associated with unfavorable neurodevelopment in children. We examined associations between prenatal exposure to traffic-related air pollution and child behavioral development milestone delays, using data from a nationwide population-based longitudinal survey in Japan, where the participants were recruited in 2001 and followed.Methods: Particulate matter, nitrogen dioxide, and sulfur dioxide concentrations during the 9 months before birth were obtained at the municipality level and assigned to the participants who were born in the corresponding municipality. We analyzed data from singleton births with linked pollution data available (N = 33,911 at the maximum). We used responses to survey questions about age-appropriate behaviors at ages 2.5 and 5.5 years as indicators of behavioral development. We conducted multilevel logistic regression analysis, adjusting for individual and municipality-level variables.Results: Air pollution exposure during gestation was positively associated with the risk of some developmental milestone delays at both ages. Specifically, air pollution was associated with verbal and fine motor development at age 2.5 years, and with behaviors related to inhibition and impulsivity at 5.5 years. In the fully-adjusted models, odds ratios following one-interquartile-range increase in nitrogen dioxide and suspended particulate matter were 1.24 (95% confidence interval: 1.07, 1.43) for inability to compose a two-phrase sentence at ages 2.5 and 1.10 (1.05, 1.16) for inability to express emotions at age 5.5 years, respectively.Conclusions: Prenatal exposure to traffic-related air pollution was associated with behavioral development milestone delays of children in a nationally representative sample in Japan. [ABSTRACT FROM AUTHOR]

Preterm births cause a large public-health burden, and air pollution is considered to be a potential risk factor. We evaluated the association between proximity to major roads (as an index for air pollution) and preterm births, classified by gestational age and specific clinical manifestations.Data on parental information and birth outcomes were extracted from the database maintained by the perinatal hospital in Shizuoka, Japan. We restricted the analysis to mothers who delivered liveborn single births from 1997 to 2008 (n = 14,226). Using the geocoded residential information, each birth was classified on its proximity to major roads. We estimated the multivariate-adjusted odds ratios and their 95% confidence intervals (CIs) for the association of proximity to major roads with preterm births, using logistic regression.We found positive associations between proximity to major roads and preterm births at all gestational ages. Living within 200 m increased the risk of births before 37 weeks by 1.5 times (95% CI = 1.2-1.8), birth before 32 weeks by 1.6 times (1.1-2.4), and births before 28 weeks by 1.8 times (1.0-3.2). Proximity specifically increased the risk of preterm births with preterm premature rupture of the membranes and with pregnancy hypertension.This study demonstrates that exposure to traffic-related air pollution increases even the risk of preterm births of less than 30 weeks' gestational age and proposes a possible mechanism. [ABSTRACT FROM AUTHOR]

The number of patients with Japanese spotted fever (JSF) and its case fatality rate have been increasing in Japan and other East Asian countries. Better clinical and laboratory biomarkers are needed to avoid misdiagnosing JSF and to predict severe cases. In addition to determining these predictors, we aimed to examine the association between the incidence of JSF and the distance from rivers, in Hiroshima Prefecture, one of the most JSF prevalent areas in Japan. Patients diagnosed with JSF from 2009 to 2017 in two hospitals in Onomichi City in Hiroshima Prefecture were studied, and their clinical characteristics and laboratory data were collected retrospectively from medical charts. A random forest was used to identify predictors of severe JSF leading to hemodialysis or death. A multivariable negative binomial regression model was utilized to analyze the association between the cumulative incidence in each postal code area and the distance from the residential postal code area to the closest river. Out of 82 patients with JSF (mean age at diagnosis, 74.1 ± 10.6 years; 34 (41.5 %) men), 6 cases were regarded as severe (among them 5 hemodialysis patients and 3 deaths). Twenty-eight (34.1 %) patients were misdiagnosed at least once at the initial hospital visit. Laboratory examination showed 34.5 % had atypical lymphocytes, 73.8 % had no eosinophils, 75.6 % had an elevated aspartate aminotransferase (AST) level, and 69.5 % had hyponatremia. Among cases without urine leucocytes, 63.3 % had proteinuria and 63.3 % had hematuria. Low serum total protein was the strongest predictor of severe JSF, followed by high blood urea nitrogen (BUN) and low albumin. Geospatial analysis showed a significant negative association between the cumulative incidence of JSF cases and the distance from rivers in an adjusted model: the cumulative incidence decreased by 0.51 times (95 % CI: 0.30 to 0.86) for every kilometer of distance from the residential postal code area to the closest river. Some laboratory data may be useful in averting misdiagnosis of JSF and in predicting severe cases. Additional studies should be done in order to clarify the mechanism and association of the incidence of JSF with the distance from the nearest river. [ABSTRACT FROM AUTHOR]

Objectives: To examine the effects of prenatal and postnatal exposure to particulate matter on Kawasaki disease (KD) occurrence, using data from a nationwide population-based longitudinal survey in Japan that began in 2010.Study Design: Prenatal and postnatal suspended particulate matter concentrations were obtained at municipality level and assigned to participants based on their municipality of birth. We analyzed data from 30 367 participants with data on either exposure period. We used hospital admission for KD from 6 to 30 months of age as the main outcome of interest. We conducted a multilevel logistic regression analysis, adjusting for individual and municipality-level variables.Results: Children who were exposed to higher levels of suspended particulate matter, in particular during pregnancy, were more likely to be hospitalized for KD. The ORs for ≥25 µg/m3 exposure compared with <20 µg/m3 exposure were 1.59 (95% CI 1.06, 2.38) for prenatal exposure and 1.41 (0.82, 2.41) for postnatal exposure. Prenatal exposure during mid-to-late gestation seemed to be more relevant for the increased risk.Conclusions: Early life exposure to particulate air pollution, in particular during pregnancy, is associated with an increased risk of KD hospital admission in early childhood in a nationally representative sample in Japan. [ABSTRACT FROM AUTHOR]