Hazuki Tamada
Current Organizations / Institutes
The organizations/institutes from the scholar's latest article
Hazuki Tamada has a total of 46 co-authors. Here are the top co-authors by number of shared publications:
- Michihiro Kamijima
Department of Occupational and Environmental Health Nagoya City University Graduate School of Medical Sciences Nagoya Japan
8 shared publications - Takeshi Ebara
Department of Ergonomics, Institute of Industrial Ecological Sciences, University of Occupational and Environmental Health, Japan , Kitakyushu
8 shared publications - Mayumi Sugiura-Ogasawara
Department of Obstetrics and Gynecology Nagoya City University Graduate School of Medical Sciences Nagoya Japan
7 shared publications - Sayaka Kato
Department of Occupational and Environmental Health Nagoya City University Graduate School of Medical Sciences Nagoya Japan
6 shared publications - Shinji Saitoh
Department of Pediatrics and Neonatology, Nagoya City University Graduate School of Medical Sciences, Nagoya 467-8601, Japan
6 shared publications - Taro Matsuki
Department of Occupational and Environmental Health, Graduate School of Medical Sciences, Nagoya City University, Mizuho-ku, Nagoya 4678601, Aichi, Japan
6 shared publications
Latest Publications
- Open Access
- 13 October 2025
- Published by Wiley in Digestive Endoscopy
- Vol. 38 (1)
The One‐Minute Triple Stretch Reduces Musculoskeletal Discomfort in Endoscopic Assistants: A Crossover Trial With Motion Analysis
Objectives: Musculoskeletal disorders (MSDs) among endoscopic assistants are a major occupational concern. While ergonomic interventions such as education and microbreaks have reduced MSDs in surgical settings, few studies have focused specifically on endoscopic assistants. This study evaluated the effectiveness of a brief stretching protocol, the one‐minute triple stretch (OMTS), in reducing MSD symptoms and improving posture. Methods: This crossover study of 10 endoscopic assistants from two hospitals used a repeated measures quasi‐experimental design. Participants were alternately assigned to a control group (standard procedures) or intervention group (OMTS every 20 min). Musculoskeletal discomfort was assessed using the Numerical Rating Scale. Work performance was evaluated via two standardized scales, and posture was analyzed using a motion tracking system. Data were collected at baseline, mid‐, and postprocedure. Results: The OMTS significantly reduced left shoulder discomfort at 120 min ( p = 0.02, Hedges' g = −0.79), exceeding the minimal clinically important difference (MCID = 1.5). Moderate, nonsignificant effects were observed in the neck and lower back. Neck flexion posture improved significantly in the OMTS group ( p = 0.03, g = −0.54), exceeding the MCID (2.9°). Conclusion: The OMTS appears to be a feasible ergonomic intervention that can reduce MSD symptoms in endoscopic assistants. Further multicenter studies are needed to confirm its effectiveness. Trial Registration: The study was registered in the UMIN Clinical Trials Registry (Registration Number: UMIN000048799) on August 31, 2022
- 13 October 2025
- Published by Wiley in Digestive Endoscopy
- Vol. 38 (1)
Open AccessThe One‐Minute Triple Stretch Reduces Musculoskeletal Discomfort in Endoscopic Assistants: A Crossover Trial With Motion Analysis
Objectives: Musculoskeletal disorders (MSDs) among endoscopic assistants are a major occupational concern. While ergonomic interventions such as education and microbreaks have reduced MSDs in surgical settings, few studies have focused specifically on endoscopic assistants. This study evaluated the effectiveness of a brief stretching protocol, the one‐minute triple stretch (OMTS), in reducing MSD symptoms and improving posture. Methods: This crossover study of 10 endoscopic assistants from two hospitals used a repeated measures quasi‐experimental design. Participants were alternately assigned to a control group (standard procedures) or intervention group (OMTS every 20 min). Musculoskeletal discomfort was assessed using the Numerical Rating Scale. Work performance was evaluated via two standardized scales, and posture was analyzed using a motion tracking system. Data were collected at baseline, mid‐, and postprocedure. Results: The OMTS significantly reduced left shoulder discomfort at 120 min ( p = 0.02, Hedges' g = −0.79), exceeding the minimal clinically important difference (MCID = 1.5). Moderate, nonsignificant effects were observed in the neck and lower back. Neck flexion posture improved significantly in the OMTS group ( p = 0.03, g = −0.54), exceeding the MCID (2.9°). Conclusion: The OMTS appears to be a feasible ergonomic intervention that can reduce MSD symptoms in endoscopic assistants. Further multicenter studies are needed to confirm its effectiveness. Trial Registration: The study was registered in the UMIN Clinical Trials Registry (Registration Number: UMIN000048799) on August 31, 2022
- Open Access
- 4 July 2025
- Published by Elsevier in Environment International
- Vol. 202, 109663
Effect of maternal bisphenol exposure on adverse pregnancy and neonatal outcomes: The Japan Environment and Children’s study
- 4 July 2025
- Published by Elsevier in Environment International
- Vol. 202, 109663
Open AccessEffect of maternal bisphenol exposure on adverse pregnancy and neonatal outcomes: The Japan Environment and Children’s study
- Open Access
Epidemiological Studies of Children’s Gut Microbiota: Validation of Sample Collection and Storage Methods and Microbiota Analysis of Toddlers’ Feces Collected from Diapers
The composition of human gut microbiota influences human health and disease over the long term. Since the flora in specimens can easily change at ambient temperature outside the body, epidemiological studies need feasible methods of stool specimen collection and storage to be established. We aimed to validate two methods: feces frozen-stored in tubes containing guanidine thiocyanate solution for two months after collection (Method B), and feces excreted in diapers and frozen-stored (Method C). Validation was by comparison with a gold standard Method A. Bacterial flora of five adults were sampled and stored by all three methods. Bacterial composition was examined by amplicon sequencing analysis. Bland–Altman analyses showed that Methods B and C might change relative abundances of certain bacterial flora. Thereafter, we analyzed the bacterial flora of 76 toddlers (two age groups) in stools sampled and processed by Method C. The diversity indices of toddlers’ flora were less than those of adults. The relative abundance of some bacteria differed significantly between children aged 1.5 and 3 years. The specimen collection and storage methods validated in this study are worth adopting in large-scale epidemiological studies, especially for small children, provided the limited accuracy for some specific bacteria is understood.
Open AccessEpidemiological Studies of Children’s Gut Microbiota: Validation of Sample Collection and Storage Methods and Microbiota Analysis of Toddlers’ Feces Collected from Diapers
The composition of human gut microbiota influences human health and disease over the long term. Since the flora in specimens can easily change at ambient temperature outside the body, epidemiological studies need feasible methods of stool specimen collection and storage to be established. We aimed to validate two methods: feces frozen-stored in tubes containing guanidine thiocyanate solution for two months after collection (Method B), and feces excreted in diapers and frozen-stored (Method C). Validation was by comparison with a gold standard Method A. Bacterial flora of five adults were sampled and stored by all three methods. Bacterial composition was examined by amplicon sequencing analysis. Bland–Altman analyses showed that Methods B and C might change relative abundances of certain bacterial flora. Thereafter, we analyzed the bacterial flora of 76 toddlers (two age groups) in stools sampled and processed by Method C. The diversity indices of toddlers’ flora were less than those of adults. The relative abundance of some bacteria differed significantly between children aged 1.5 and 3 years. The specimen collection and storage methods validated in this study are worth adopting in large-scale epidemiological studies, especially for small children, provided the limited accuracy for some specific bacteria is understood.
- Open Access
Impact of Ready-Meal Consumption during Pregnancy on Birth Outcomes: The Japan Environment and Children’s Study
Ready-meal consumption is increasing worldwide; however, its impact on human health remains unclear. We aimed to examine the association between processed food and beverage consumption during pregnancy and pregnancy outcomes. Pregnant women were recruited for the Japan Environment and Children’s Study (JECS), a nationwide, large-scale, prospective cohort study. This study included 104,102 registered children (including fetuses or embryos) and collected questionnaire-based data during the first and second/third trimester of pregnancy. Participants’ medical records were transcribed at pregnancy registration, immediately after delivery, and 1 month after delivery. Logistic regression analysis was used to estimate the association between processed food consumption and pregnancy outcomes. The incidence of stillbirth was higher in the group that consumed moderate (1–2 times per week) and high (≥3–7 times per week) amounts of ready-meals (adjusted odds ratio (aOR) = 2.054, 95% confidence interval (CI): 1.442–2.926, q = 0.002; aOR = 2.632, 95% CI: 1.507–4.597, q = 0.007, respectively) or frozen meals (aOR = 2.225, 95% CI: 1.679–2.949, q < 0.001; aOR = 2.170, 95% CI: 1.418–3.322, q = 0.005, respectively) than in the group that rarely consumed such foods. Processed food consumption during pregnancy should be carefully considered.
Open AccessImpact of Ready-Meal Consumption during Pregnancy on Birth Outcomes: The Japan Environment and Children’s Study
Ready-meal consumption is increasing worldwide; however, its impact on human health remains unclear. We aimed to examine the association between processed food and beverage consumption during pregnancy and pregnancy outcomes. Pregnant women were recruited for the Japan Environment and Children’s Study (JECS), a nationwide, large-scale, prospective cohort study. This study included 104,102 registered children (including fetuses or embryos) and collected questionnaire-based data during the first and second/third trimester of pregnancy. Participants’ medical records were transcribed at pregnancy registration, immediately after delivery, and 1 month after delivery. Logistic regression analysis was used to estimate the association between processed food consumption and pregnancy outcomes. The incidence of stillbirth was higher in the group that consumed moderate (1–2 times per week) and high (≥3–7 times per week) amounts of ready-meals (adjusted odds ratio (aOR) = 2.054, 95% confidence interval (CI): 1.442–2.926, q = 0.002; aOR = 2.632, 95% CI: 1.507–4.597, q = 0.007, respectively) or frozen meals (aOR = 2.225, 95% CI: 1.679–2.949, q < 0.001; aOR = 2.170, 95% CI: 1.418–3.322, q = 0.005, respectively) than in the group that rarely consumed such foods. Processed food consumption during pregnancy should be carefully considered.
- Open Access
- 1 January 2022
- Published by Japanese Society for Hygiene in Environmental Health and Preventive Medicine
- Vol. 27, 25
Simultaneous quantification of pyrethroid metabolites in urine of non-toilet-trained children in Japan
Background: Pyrethroid (PYR) insecticides are widely used for controlling various pests. There are two types that differ in terms of usage: agricultural-purpose PYR (agriculture-PYR) and hygiene purpose PYR (hygiene-PYRs). Few studies exist on the exposure to these chemicals in small children. In this study, we conducted biomonitoring of urinary pyrethroid metabolites in 1.5-year-old children throughout the year.Methods: Study subjects were 1075 children participating in an Aichi regional sub-cohort of the Japan Environment and Children’s Study as of 18-month health check-up. The concentrations of four specific hygiene-PYR metabolites including 2,3,5,6-tetrafluoro-1,4-benzenedimethanol (HOCH2-FB-Al), and five common metabolites of hygiene- and agriculture-PYRs including 3-phenoxybenzoic acid (3PBA) and cis- and trans-3-(2,2-dichlorovinyl)-2,2-dimethylcyclopropane-1-carboxylic acid (DCCA), were measured in urine samples extracted from soiled diapers using a triple quadrupole gas chromatograph-mass spectrometer.Results: The highest detection frequencies were for 3PBA, followed by DCCA, 1R-trans-chrysanthemum dicarboxylic acid, and HOCH2-FB-Al. Among the six metabolites, urinary concentrations were seasonally varied. However, this variation was not observed in the most studied PYR metabolite, 3PBA. Spearman’s correlation analysis demonstrated a significant positive correlation between FB-Al and DCCA (r = 0.56) and HOCH2-FB-Al and 4-methoxymethyl-2,3,5,6-tetrafluorobenzyl alcohol (r = 0.60).Conclusions: This biomonitoring survey found widespread and seasonally specific exposure to multiple hygiene- and agriculture-PYRs in 1.5-year-old Japanese children.
- 1 January 2022
- Published by Japanese Society for Hygiene in Environmental Health and Preventive Medicine
- Vol. 27, 25
Open AccessSimultaneous quantification of pyrethroid metabolites in urine of non-toilet-trained children in Japan
Background: Pyrethroid (PYR) insecticides are widely used for controlling various pests. There are two types that differ in terms of usage: agricultural-purpose PYR (agriculture-PYR) and hygiene purpose PYR (hygiene-PYRs). Few studies exist on the exposure to these chemicals in small children. In this study, we conducted biomonitoring of urinary pyrethroid metabolites in 1.5-year-old children throughout the year.Methods: Study subjects were 1075 children participating in an Aichi regional sub-cohort of the Japan Environment and Children’s Study as of 18-month health check-up. The concentrations of four specific hygiene-PYR metabolites including 2,3,5,6-tetrafluoro-1,4-benzenedimethanol (HOCH2-FB-Al), and five common metabolites of hygiene- and agriculture-PYRs including 3-phenoxybenzoic acid (3PBA) and cis- and trans-3-(2,2-dichlorovinyl)-2,2-dimethylcyclopropane-1-carboxylic acid (DCCA), were measured in urine samples extracted from soiled diapers using a triple quadrupole gas chromatograph-mass spectrometer.Results: The highest detection frequencies were for 3PBA, followed by DCCA, 1R-trans-chrysanthemum dicarboxylic acid, and HOCH2-FB-Al. Among the six metabolites, urinary concentrations were seasonally varied. However, this variation was not observed in the most studied PYR metabolite, 3PBA. Spearman’s correlation analysis demonstrated a significant positive correlation between FB-Al and DCCA (r = 0.56) and HOCH2-FB-Al and 4-methoxymethyl-2,3,5,6-tetrafluorobenzyl alcohol (r = 0.60).Conclusions: This biomonitoring survey found widespread and seasonally specific exposure to multiple hygiene- and agriculture-PYRs in 1.5-year-old Japanese children.
- Open Access
- 29 October 2021
- Published by MDPI AG in International Journal of Environmental Research and Public Health
- Vol. 18 (21) , 11373
Relationship between Physical Activity and Physical and Mental Health Status in Pregnant Women: A Prospective Cohort Study of the Japan Environment and Children’s Study
To discuss appropriate physical activity (PA) levels during pregnancy, this prospective cohort study examined the relationships between PA levels before and during pregnancy and physical and mental health status. Fixed data for 104,102 pregnant women were used from the Japan Environment and Children’s Study, of which data for 82,919 women were analyzed after excluding women with multiple birth and pregnancy complications. PA levels were measured using the International Physical Activity Questionnaire-Short Form. The 8-Item Short Form Health Survey was used to measure outcomes. Logistic regression with multiple imputations showed that moderate PA for over 720 min/wk and vigorous PA before pregnancy were associated with poorer mental health in the first trimester (adjusted odds ratio (AOR): 1.087–1.376. Walking in the second and third trimesters was associated with better physical and mental health (AOR: 0.855–0.932). Moderate PA over 1080 min/wk and vigorous PA in the second and third trimesters were associated with poorer mental health (AOR: 1.223–1.873). Increases over 4135.4 MET–min/wk and decreases in PA levels were associated with poorer mental and physical health (AOR: 1.070–1.333). Namely, pregnant women receiving health benefits prefer continuous walking in addition to avoiding vigorous PA and excessive changes in PA levels during pregnancy.
- 29 October 2021
- Published by MDPI AG in International Journal of Environmental Research and Public Health
- Vol. 18 (21) , 11373
Open AccessRelationship between Physical Activity and Physical and Mental Health Status in Pregnant Women: A Prospective Cohort Study of the Japan Environment and Children’s Study
To discuss appropriate physical activity (PA) levels during pregnancy, this prospective cohort study examined the relationships between PA levels before and during pregnancy and physical and mental health status. Fixed data for 104,102 pregnant women were used from the Japan Environment and Children’s Study, of which data for 82,919 women were analyzed after excluding women with multiple birth and pregnancy complications. PA levels were measured using the International Physical Activity Questionnaire-Short Form. The 8-Item Short Form Health Survey was used to measure outcomes. Logistic regression with multiple imputations showed that moderate PA for over 720 min/wk and vigorous PA before pregnancy were associated with poorer mental health in the first trimester (adjusted odds ratio (AOR): 1.087–1.376. Walking in the second and third trimesters was associated with better physical and mental health (AOR: 0.855–0.932). Moderate PA over 1080 min/wk and vigorous PA in the second and third trimesters were associated with poorer mental health (AOR: 1.223–1.873). Increases over 4135.4 MET–min/wk and decreases in PA levels were associated with poorer mental and physical health (AOR: 1.070–1.333). Namely, pregnant women receiving health benefits prefer continuous walking in addition to avoiding vigorous PA and excessive changes in PA levels during pregnancy.
- Open Access
- 20 August 2021
- Published by The Endocrine Society in The Journal of Clinical Endocrinology & Metabolism
- Vol. 107 (1) , e118-e129
Association of Maternal Total Cholesterol With SGA or LGA Birth at Term: the Japan Environment and Children’s Study
Context Maternal cholesterol is important for fetal development. Whether maternal serum total cholesterol (maternal TC) levels in midpregnancy are associated with small (SGA) or large (LGA) for gestational age independent of prepregnancy body mass index (BMI) and weight gain during pregnancy is inconclusive. Objective This work aimed to prospectively investigate the association between maternal TC in midpregnancy and SGA or LGA. Methods The Japan Environment and Children’s Study is a nationwide prospective birth cohort study in Japan. Participants in this study included 37 449 nondiabetic, nonhypertensive mothers with singleton birth at term without congenital abnormalities. Birth weight for gestational age less than the 10th percentile and greater than or equal to the 90th percentile were respectively defined as SGA and LGA by the Japanese neonatal anthropometric charts. Results The mean gestational age at blood sampling was 22.7 ± 4.0 weeks. After adjustment for maternal age, sex of child, parity, weight gain during pregnancy, prepregnancy BMI, smoking, alcohol drinking, blood glucose levels, household income, and study areas, 1-SD decrement of maternal TC was linearly associated with SGA (odds ratio [OR]: 1.20; 95% CI, 1.15-1.25). In contrast, 1-SD increment of maternal TC was linearly associated with LGA (OR: 1.13; 95% CI, 1.09-1.16). Associations did not differ according to prepregnancy BMI and gestational weight gain (P for interaction > .20). Conclusion Maternal TC levels in midpregnancy were associated with SGA or LGA in a Japanese cohort. It may help to predict SGA and LGA. Favorable maternal lipid profiles for fetal development must be explored.
- 20 August 2021
- Published by The Endocrine Society in The Journal of Clinical Endocrinology & Metabolism
- Vol. 107 (1) , e118-e129
Open AccessAssociation of Maternal Total Cholesterol With SGA or LGA Birth at Term: the Japan Environment and Children’s Study
Context Maternal cholesterol is important for fetal development. Whether maternal serum total cholesterol (maternal TC) levels in midpregnancy are associated with small (SGA) or large (LGA) for gestational age independent of prepregnancy body mass index (BMI) and weight gain during pregnancy is inconclusive. Objective This work aimed to prospectively investigate the association between maternal TC in midpregnancy and SGA or LGA. Methods The Japan Environment and Children’s Study is a nationwide prospective birth cohort study in Japan. Participants in this study included 37 449 nondiabetic, nonhypertensive mothers with singleton birth at term without congenital abnormalities. Birth weight for gestational age less than the 10th percentile and greater than or equal to the 90th percentile were respectively defined as SGA and LGA by the Japanese neonatal anthropometric charts. Results The mean gestational age at blood sampling was 22.7 ± 4.0 weeks. After adjustment for maternal age, sex of child, parity, weight gain during pregnancy, prepregnancy BMI, smoking, alcohol drinking, blood glucose levels, household income, and study areas, 1-SD decrement of maternal TC was linearly associated with SGA (odds ratio [OR]: 1.20; 95% CI, 1.15-1.25). In contrast, 1-SD increment of maternal TC was linearly associated with LGA (OR: 1.13; 95% CI, 1.09-1.16). Associations did not differ according to prepregnancy BMI and gestational weight gain (P for interaction > .20). Conclusion Maternal TC levels in midpregnancy were associated with SGA or LGA in a Japanese cohort. It may help to predict SGA and LGA. Favorable maternal lipid profiles for fetal development must be explored.
- Open Access
- 26 June 2020
- Published by MDPI AG in International Journal of Environmental Research and Public Health
- Vol. 17 (12) , 4608
Association between Prenatal Exposure to Household Pesticides and Neonatal Weight and Length Growth in the Japan Environment and Children’s Study
The effects of prenatal exposure to household pesticides on fetal and neonatal growth have not been fully clarified. The present study aims to determine the effects of prenatal exposure to pesticides on neonates’ body size and growth during the first month. This study included 93,718 pairs of pregnant women and their children from the Japan Environment and Children’s Study. Participants completed self-reporting questionnaires during their second or third trimesters on their demographic characteristics and frequency of pesticide use during pregnancy. Child weight, length, and sex were obtained from medical record transcripts. Birth weight and length, as well as weight and length changes over the first month, were estimated using an analysis of covariance. Frequency of exposure to almost all pesticides had no effects on birth weight and length. However, we found small but significant associations (i) between the use of fumigation insecticides and decreased birth weight, and (ii) between frequencies of exposure to pyrethroid pesticides, especially mosquito coils/mats, and suppression of neonatal length growth. Prenatal exposure to household pesticides, especially those containing pyrethroids, might adversely influence fetal and postnatal growth trajectories.
- 26 June 2020
- Published by MDPI AG in International Journal of Environmental Research and Public Health
- Vol. 17 (12) , 4608
Open AccessAssociation between Prenatal Exposure to Household Pesticides and Neonatal Weight and Length Growth in the Japan Environment and Children’s Study
The effects of prenatal exposure to household pesticides on fetal and neonatal growth have not been fully clarified. The present study aims to determine the effects of prenatal exposure to pesticides on neonates’ body size and growth during the first month. This study included 93,718 pairs of pregnant women and their children from the Japan Environment and Children’s Study. Participants completed self-reporting questionnaires during their second or third trimesters on their demographic characteristics and frequency of pesticide use during pregnancy. Child weight, length, and sex were obtained from medical record transcripts. Birth weight and length, as well as weight and length changes over the first month, were estimated using an analysis of covariance. Frequency of exposure to almost all pesticides had no effects on birth weight and length. However, we found small but significant associations (i) between the use of fumigation insecticides and decreased birth weight, and (ii) between frequencies of exposure to pyrethroid pesticides, especially mosquito coils/mats, and suppression of neonatal length growth. Prenatal exposure to household pesticides, especially those containing pyrethroids, might adversely influence fetal and postnatal growth trajectories.