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Wang Z, Sun Y, Dong JJ, Shi LL, Nakayama SF, Kido T, Jung CR, Ma C, Feng H, Hang JG, Sun XL. Relationship between dioxins and steroid hormone in 6-year-olds: A follow-up study in an e-waste region of China. CHEMOSPHERE 2022; 296:134018. [PMID: 35181420 DOI: 10.1016/j.chemosphere.2022.134018] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/30/2021] [Revised: 02/13/2022] [Accepted: 02/14/2022] [Indexed: 06/14/2023]
Abstract
We conducted a follow-up observational study on the effects of dioxin exposure on the synthesis of steroid hormones in infants during the perinatal period. The participants included 42 pairs of mothers and infants that were previously studied in 2015. We analyzed four types of steroid hormones including progesterone, testosterone, androstenedione (A-dione), and dehydroepiandrosterone (DHEA) in the serum samples of 6-year-olds and the concentration of dioxins in breast milk. A multivariate linear regression was performed to associate steroid hormones (dependent variables) and dioxins with the body mass index (BMI), sex, age, and residence of participants (independent variables). The results were reported as β (standardized coefficient) and p-values. We found that dioxins have a significant negative correlation with DHEA and A-dione but no significant relationship with progesterone and testosterone. However, in previous studies, we found that testosterone and progesterone levels were significantly related to dioxins in 4-year-olds. We concluded that dioxins can affect the level of steroid hormones, but their effects fluctuate, and the harm caused by dioxins in children requires further long-term monitoring.
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Affiliation(s)
- Zheng Wang
- School of Medicine, Jiaxing University, 118 Jiahang Road, Jiaxing, 314001, China
| | - Ying Sun
- School of Medicine, Jiaxing University, 118 Jiahang Road, Jiaxing, 314001, China
| | - Jing Jian Dong
- School of Medicine, Jiaxing University, 118 Jiahang Road, Jiaxing, 314001, China
| | - Li Li Shi
- School of Medicine, Jiaxing University, 118 Jiahang Road, Jiaxing, 314001, China
| | - Shoji F Nakayama
- Centre for Health and Environmental Risk Research, National Institute for Environmental Studies, 16-2 Onogawa, Tsukuba, 3058506, Japan
| | - Teruhiko Kido
- Faculty of Health Sciences, Institute of Medical, Pharmaceutical, and Health Sciences, Kanazawa University, 5-11-80 Kodatsuno, Kanazawa, 9200942, Japan
| | - Chau-Ren Jung
- Department of Public Health, College of Public Health, China Medical University, Taichung, 406040, Taiwan
| | - Chaochen Ma
- Cancer Control Center, Osaka International Cancer Institute, Osaka, 541-8567, Japan
| | - Hao Feng
- School of Medicine, Jiaxing University, 118 Jiahang Road, Jiaxing, 314001, China
| | - Jin Guo Hang
- Taizhou Hospital of Zhejiang Province Affiliated to Wenzhou Medical University, Taizhou, 318050, China.
| | - Xian Liang Sun
- School of Medicine, Jiaxing University, 118 Jiahang Road, Jiaxing, 314001, China; Faculty of Health Sciences, Institute of Medical, Pharmaceutical, and Health Sciences, Kanazawa University, 5-11-80 Kodatsuno, Kanazawa, 9200942, Japan.
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Manh HD, Kido T, Takasuga T, Yamashita M, Giang LM, Nakagawa H. The Relationship of Dioxin Levels in Serum of 9-Year-Old Vietnamese Children and Their Mothers’ Breast Milk. TOXICS 2022; 10:toxics10040155. [PMID: 35448416 PMCID: PMC9030040 DOI: 10.3390/toxics10040155] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/04/2022] [Revised: 03/14/2022] [Accepted: 03/19/2022] [Indexed: 02/04/2023]
Abstract
In this study, we measured the concentrations of polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs) in the blood of 9-year-old children living in a dioxin hotspot area and a nonexposed area in Vietnam. Forty-five blood samples were collected in the hotspot area while twelve pooled blood samples were collected in the nonexposed area. We found that the dioxin level of children in the hotspot was significantly higher than that of children in the nonexposed area. The total TEQ of PCDD/Fs in the hotspot and the nonexposed was 10.7 and 3.3 pg TEQ/g fat, respectively. However, TCDD, the maker of Agent Orange, was not detected in the blood of children in the hotspot area. In the hotspot area, four congeners 1,2,3,4,6,7,8-HpCDD, 1,2,3,4,7,8-HxCDF, 1,2,3,6,7,8-HxCDF, and 1,2,3,4,6,7,8-HpCDF in mothers’ breast milk showed a significantly positive correlation with those in children’s serum although the correlations of 1,2,3,7,8-PeCDD and 2,3,4,7,8-PeCDF were not significant. In addition, the duration of breastfeeding also correlates with dioxins in children. These results suggested that children in the hotspot area were exposed to dioxin through mothers’ milk and other foods or environmental factors. The present study is the first study that shows dioxin levels in Vietnamese children.
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Affiliation(s)
- Ho Dung Manh
- Faculty of Pharmacy, Lac Hong University, No. 10 Huynh Van Nghe, Buu Long, Bien Hoa 02513, Dong Nai, Vietnam;
| | - Teruhiko Kido
- Division of Health Sciences, Graduate School of Medical Science, Kanazawa University, 5-11-80 Kodatsuno, Kanazawa 920-0942, Japan
- Correspondence: ; Tel.: +81-762652565
| | - Takumi Takasuga
- Shimadzu Techno-Research Inc., 1 Nishinokyo Shimoaicho Nakagyo-ku, Kyoto 604-8436, Japan; (T.T.); (M.Y.)
| | - Michiko Yamashita
- Shimadzu Techno-Research Inc., 1 Nishinokyo Shimoaicho Nakagyo-ku, Kyoto 604-8436, Japan; (T.T.); (M.Y.)
| | - Le Minh Giang
- 10-80 Division, Hanoi Medical University, No. 1 Ton That Tung, Dong Da, Hanoi 116500, Vietnam;
| | - Hideaki Nakagawa
- Department of Hygiene, Kanazawa Medical University, 1-1 Daigaku, Uchinada, Kahoku 920-0265, Japan;
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Oyama Y, Phuc HD, Honma S, Oanh NTP, Hung NX, Anh LT, Manh HD, Van Tung D, Nhu DD, Tan NM, Van Thuc P, Minh NH, Van Toan N, Okamoto R, Omote S, Nakagawa H, Van Chi V, Kido T. Decreased serum testosterone levels associated with 17β-hydroxysteroid dehydrogenase activity in 7-year-old children from a dioxin-exposed area of Vietnam. THE SCIENCE OF THE TOTAL ENVIRONMENT 2021; 783:146701. [PMID: 33865132 DOI: 10.1016/j.scitotenv.2021.146701] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/16/2020] [Revised: 03/18/2021] [Accepted: 03/19/2021] [Indexed: 06/12/2023]
Abstract
Since 2008, we have conducted epidemiological cohort studies on the relationship between dioxin exposure and disruption with children in the area sprayed with defoliants during the Vietnam War. In a long-term survey of children through the age of five, we observed androgen disruption due to decreased dehydroepiandrosterone (DHEA) and testosterone levels. In this study of 7-year-old, we separately elucidated androgen disruption for boys and girls, and discussed with respect to hormone disruption with sex differences on the steroid hormone biosynthesis process. This follow-up was conducted with 96 mother-child pairs in Vietnam (hotspot area: 45, non-sprayed area: 51). We took a questionnaire, the physical measurement and assayed 7 steroid hormones in their serum by LC-MS/MS. We examined the relationship between the hormone levels in the serum and dioxin levels in the maternal breast milk. The results showed that the serum DHEA level in the 7-year-old children in the hotspot recovered to levels in the non-sprayed area. The testosterone level of 66.5 pg/mL for boys in the non-sprayed area was 1.5 times the girls level of 44.6 pg/mL, a male-dominant effect. The testosterone level in boys and girls from the hotspot were significantly lower than in the non-sprayed area with no sex difference. The 17β-hydroxysteroid dehydrogenase (17β-HSD) activity was significantly higher in boys than in the girls from the non-sprayed area, but was significantly lower in the hotspot boys than in the non-sprayed area boys. Both the testosterone level and 17β-HSD activity in the boys were inversely correlated with the TEQ total PCDD/Fs in the maternal breast milk. These results indicated that dioxin delayed the expression of the testosterone level and 17β-HSD activity with growth in the 7-year-old boys. The serum DHEA in the 7-year-old children recovered to the levels of the children in the non-sprayed area.
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Affiliation(s)
- Yuko Oyama
- Division of Health Sciences, Graduate School of Medical Science, Kanazawa University, Japan
| | - Hoang Duc Phuc
- Hanoi Centre for Disease Control, No. 70 Nguyen Chi Thanh, Dong Da, Hanoi, Viet Nam.
| | - Seijiro Honma
- Faculty of Health Sciences, Institute of Medical, Pharmaceutical and Health Sciences, Kanazawa University, Japan
| | - Nguyen Thi Phuong Oanh
- Department of Environmental Health, Institute of Preventive Medicine and Public Health, Hanoi Medical University, No1 Ton That Tung Dong Da, Hanoi, Viet Nam
| | - Nguyen Xuan Hung
- Center for Research and Technology Transfer, Viet Nam Academy of Science and Technology, 18 Hoang Quoc Viet, Cau Giay, Ha Noi, Viet Nam
| | | | - Ho Dung Manh
- Faculty of Pharmacy, Lac Hong University, No. 10 Huynh Van Nghe, Buu Long, Bien Hoa, Dong Nai, Viet Nam
| | - Dao Van Tung
- Hai Phong Medical College, No.169 Tran Nguyen Han, Le Chan, Hai Phong, Viet Nam
| | - Dang Duc Nhu
- Ministry of Health, No 138A Giang Vo, Ba Dinh, Hanoi, Viet Nam
| | - Ngo Minh Tan
- Hanoi Medical University, No. 1 Ton That Tung, Dong Da, Hanoi, Viet Nam
| | - Pham Van Thuc
- Hanoi Medical University, No. 1 Ton That Tung, Dong Da, Hanoi, Viet Nam
| | - Nguyen Hung Minh
- Dioxin Laboratory, Centre for Environment Monitoring, Vietnam Environment Administration, Hanoi, Viet Nam
| | - Ngo Van Toan
- Department of Environmental Health, Institute of Preventive Medicine and Public Health, Hanoi Medical University, No1 Ton That Tung Dong Da, Hanoi, Viet Nam
| | - Rie Okamoto
- Faculty of Health Sciences, Institute of Medical, Pharmaceutical and Health Sciences, Kanazawa University, Japan
| | - Shizuko Omote
- Faculty of Health Sciences, Institute of Medical, Pharmaceutical and Health Sciences, Kanazawa University, Japan
| | - Hideaki Nakagawa
- Department of Epidemiology and Public Health, Kanazawa Medical University, Japan
| | - Vo Van Chi
- Phu Cat Health Centre, No.12, 2/3 St., Ngo May, Phu Cat, Binh Dinh, Viet Nam
| | - Teruhiko Kido
- Faculty of Health Sciences, Institute of Medical, Pharmaceutical and Health Sciences, Kanazawa University, Japan
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Pham TN, Nishijo M, Pham TT, Vu HT, Tran NN, Tran AH, Do Q, Takiguchi T, Nishino Y, Nishijo H. Dioxin exposure and sexual dimorphism of gaze behavior in prepubertal Vietnamese children living in Da Nang, a hot spot for dioxin contamination. THE SCIENCE OF THE TOTAL ENVIRONMENT 2020; 749:141083. [PMID: 32829268 DOI: 10.1016/j.scitotenv.2020.141083] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/06/2020] [Revised: 07/17/2020] [Accepted: 07/17/2020] [Indexed: 06/11/2023]
Abstract
Previous studies have reported that dioxin exposure alters sexual dimorphism of play behavior in pre-pubertal children. We aimed to investigate the effects of perinatal dioxin exposure, indicated by dioxins in breast milk, on sexual dimorphism of gaze behavior after adjusting for salivary testosterone (T). Participants were pre-pubertal children in a hot spot for dioxin contamination originating from herbicide spraying in Vietnam. We used eye tracking to assess gaze behavior in 172 children (100 boys and 72 girls) aged 8-9 years. Two sets of 15 pairs of pictures, one oriented towards boys and one oriented towards girls, containing 5 pairs of toy photos (non-biological stimuli) and 10 pairs of human line drawings (biological stimuli) were shown to all children. The total fixation duration for each picture was extracted using Tobii studio software and a feminine index of gaze behavior was defined as the ratio of the summed fixation duration for the girl- vs boy-oriented versions of each stimuli. When viewing non-biological stimuli, feminine index scores significantly increased with TCDD (β = 0.294) in girls only. For biological stimuli, however, feminine index scores significantly increased with TEQ-PCDD/Fs (β = 0.269) in boys and with TCDD in girls (β = 0.286). These associations were significant even after adjusting for salivary T levels, which were inversely associated with some dioxin congeners in girls. In addition, increased feminine index scores for biological stimuli were associated with lower cognitive scores for hand-movement and word-order tests in boys and for face-recognition tests in girls examined at 5 years of age. In conclusion, these results suggest that perinatal dioxin exposure may increase visual interest in girl-oriented objects through impairment of cognitive abilities in pre-pubertal Vietnamese children. PCDD congeners were associated with gaze behavior independently of T levels in boys, while this was only the case for TCDD levels in girls.
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Affiliation(s)
- Thao Ngoc Pham
- Department of Public Health, Kanazawa Medical University, Japan; Biomedical and Pharmaceutical Research Center, Vietnamese Military Medical University, Viet Nam
| | - Muneko Nishijo
- Department of Public Health, Kanazawa Medical University, Japan.
| | - Tai The Pham
- Biomedical and Pharmaceutical Research Center, Vietnamese Military Medical University, Viet Nam
| | - Hoa Thi Vu
- Department of Public Health, Kanazawa Medical University, Japan
| | | | - Anh Hai Tran
- Biomedical and Pharmaceutical Research Center, Vietnamese Military Medical University, Viet Nam
| | - Quyet Do
- Biomedical and Pharmaceutical Research Center, Vietnamese Military Medical University, Viet Nam
| | | | | | - Hisao Nishijo
- System Emotional Science, Graduate School of Medicine, University of Toyama, Japan
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Shi LL, Wang MQ, Nakayama SF, Jung CR, Wang YH, Dong JJ, Ma CC, Kido T, Sun XL, Feng H. The association between dioxins and steroid hormones in general adult males: a cross-sectional study in an e-waste region of China. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2020; 27:26511-26519. [PMID: 32367235 DOI: 10.1007/s11356-020-09086-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/06/2020] [Accepted: 04/27/2020] [Indexed: 06/11/2023]
Abstract
As observed among residents in electronic waste (e-waste) recycling areas, dioxins can disrupt the homeostasis of endocrine hormones and the balance of thyroid hormones. Few studies, however, have examined whether e-waste recycling activities influence steroid hormone equilibrium in the general adult male population. This study evaluated the association between steroid hormones and the physical burdens of dioxins in the general adult male population residing in an e-waste region. In September 2017, 74 adult males residing in an e-waste dismantling region were enrolled in the current study. Approximately 10 mL of blood was collected from each adult male, and the serum samples were separated through centrifugation. Then, the levels of dioxin and steroid hormones in the serum of the participants were measured. We treated dioxin levels as categorical variables in the general linear model according to quartiles (25, 50, and 75 percentile). Comparing the findings with a reference group (< 25th percentile), we noted significantly higher dehydroepiandrosterone (DHEA) level in men with low serum polychlorinated dibenzofuran-toxic equivalent (PCDFs-TEQ) level between 3.80 and 6.31 pg/g lipid (1933 vs. 1447 pg/ml) and low polychlorinated dibenzo-p-dioxins and dibenzofurans-TEQ (PCDD/PCDFs-TEQ) between 8.57 and 15.11 pg/g lipid (1996 vs. 1360 pg/ml). Moreover, a significantly higher androstenedione (A-dione) level was found in men whose serum PCDFs-TEQ ≥ 11.34 pg/g lipd (2404 vs. 1848). What's more, there were significantly higher 3β-hydroxysteroid dehydrogenase (3β-HSD) concentrations in low- and high-2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) groups (1.30-1.67 and ≥ 2.64 pg-TEQ/g lipid, respectively with 719 and 807 vs. 496, respectively). Our findings suggest that specific dioxin exposure may disturb normal DHEA, A-dione levels, and enzyme activity in the general adult male population in an e-waste region of China.
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Affiliation(s)
- Li Li Shi
- School of Medicine, Jiaxing University, 118 Jiahang Road, Jiaxing, 314001, China
| | - Mei Qin Wang
- Taizhou Luqiao Hospital of Traditional Chinese Medicine, Luqiao, Taizhou, 318050, China
| | - Shoji F Nakayama
- Centre for Health and Environmental Risk Research, National Institute for Environmental Studies, 16-2 Onogawa, Tsukuba, 3058506, Japan
| | - Chau-Ren Jung
- Centre for Health and Environmental Risk Research, National Institute for Environmental Studies, 16-2 Onogawa, Tsukuba, 3058506, Japan
| | - Yue Hua Wang
- Taizhou Luqiao Hospital of Traditional Chinese Medicine, Luqiao, Taizhou, 318050, China
| | - Jing Jian Dong
- School of Medicine, Jiaxing University, 118 Jiahang Road, Jiaxing, 314001, China
| | - Chao Chen Ma
- Centre for Health and Environmental Risk Research, National Institute for Environmental Studies, 16-2 Onogawa, Tsukuba, 3058506, Japan
| | - Teruhiko Kido
- Faculty of Health Sciences, Institute of Medical, Pharmaceutical, and Health Sciences, Kanazawa University, 5-11-80 Kodatsuno, Kanazawa, 9200942, Japan
| | - Xian Liang Sun
- School of Medicine, Jiaxing University, 118 Jiahang Road, Jiaxing, 314001, China.
- Faculty of Health Sciences, Institute of Medical, Pharmaceutical, and Health Sciences, Kanazawa University, 5-11-80 Kodatsuno, Kanazawa, 9200942, Japan.
- JSPS International Research Fellow, Centre for Health and Environmental Risk Research, National Institute for Environmental Studies, Tsukuba, Japan.
| | - Hao Feng
- School of Medicine, Jiaxing University, 118 Jiahang Road, Jiaxing, 314001, China.
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Oanh NTP, Kido T, Honma S, Oyama Y, Anh LT, Phuc HD, Viet NH, Manh HD, Okamoto R, Nakagawa H, Nakayama SF, Nhu DD, Van Tung D, Van Chi V, Minh NH, Van Toan N. Androgen disruption by dioxin exposure in 5-year-old Vietnamese children: Decrease in serum testosterone level. THE SCIENCE OF THE TOTAL ENVIRONMENT 2018; 640-641:466-474. [PMID: 29864660 DOI: 10.1016/j.scitotenv.2018.05.257] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/15/2018] [Revised: 04/27/2018] [Accepted: 05/21/2018] [Indexed: 05/09/2023]
Abstract
Dioxins have been suspected to be potential substances causing endocrine disruptions in humans. We are conducting the research in one of three dioxin exposure areas (hotspots) in Vietnam. We previously reported that the salivary dehydroepiandrosterone (DHEA) level decreased in 3-year-old Vietnamese children and that it was significantly inversely correlated with polychlorinated dibenzodioxin/dibenzofuran levels in their mother's breast milk. In this study, we investigated the influence of exposure to dioxin on steroid hormone biosynthesis in the same children when they reached 5 years of age, focusing on androgens. Thirty-five and 50 mother-child pairs from dioxin hotspot and non-sprayed areas, respectively, participated in this study. Maternal breast milk was donated at 4 to 16 weeks postpartum in 2008 to measure dioxin levels by gas chromatography/high-resolution mass spectrometry. Serum was collected from 5-year-old children in 2013. Seven steroid hormones were measured by liquid chromatography/mass spectrometry. Most dioxin congeners in breast milk were 2- to 10-fold higher in the hotspot than in the non-sprayed area. DHEA and testosterone (T) were significantly lower in the hotspot and showed negative correlations with most dioxin congeners. Similar results were observed for the activities of cytochrome P450-17, 20 lyase (CYP17 lyase), and 17β-hydroxysteroid dehydrogenase (HSD). Conversely, the elevated androstenedione (A-dione) level and 3β-HSD activity in children from the hotspot were positively correlated with dioxin levels. Moreover, a positive correlation was shown between T and 17β-HSD. It is possible that dioxin inhibits 17β-HSD activity, leading to a decrease in the T level. Multiple regression analysis indicated that dioxin had a strong association with the DHEA, A-dione, and T levels. In conclusion, the present study suggests that dioxin is associated with low levels of DHEA and T and inhibition of the activity of steroidogenic enzymes such as CYP17 lyase and 17β-HSD in 5-year-old children.
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Affiliation(s)
- Nguyen Thi Phuong Oanh
- Division of Health Science, Graduate School of Medical Science, Kanazawa University, 5-11-80 Kodatsuno, Kanazawa, Japan
| | - Teruhiko Kido
- Faculty of Health Sciences, Institute of Medical, Pharmaceutical and Health Sciences, Kanazawa University, 5-11-80 Kodatsuno, Kanazawa, Japan.
| | - Seijiro Honma
- Faculty of Health Sciences, Institute of Medical, Pharmaceutical and Health Sciences, Kanazawa University, 5-11-80 Kodatsuno, Kanazawa, Japan
| | - Yuko Oyama
- Division of Health Science, Graduate School of Medical Science, Kanazawa University, 5-11-80 Kodatsuno, Kanazawa, Japan
| | - Le Thai Anh
- Division of Health Science, Graduate School of Medical Science, Kanazawa University, 5-11-80 Kodatsuno, Kanazawa, Japan
| | - Hoang Duc Phuc
- Hanoi Preventive Medicine Centre, No. 70 Nguyen Chi Thanh, Dong Da, Hanoi, Viet Nam
| | - Nguyen Hoang Viet
- Faculty of Medical Technology, Ha Noi Medical University, No. 1 Ton That Tung, Dong Da, Hanoi, Viet Nam
| | - Ho Dung Manh
- Faculty of Pharmacy, Lac Hong University, No. 10 Huynh Van Nghe, Buu Long, Bien Hoa, Dong Nai, Viet Nam
| | - Rie Okamoto
- Faculty of Health Sciences, Institute of Medical, Pharmaceutical and Health Sciences, Kanazawa University, 5-11-80 Kodatsuno, Kanazawa, Japan
| | - Hideaki Nakagawa
- Department of Epidemiology and Public Health, Kanazawa Medical University, 1-1 Daigaku, Uchinada, Japan
| | - Shoji F Nakayama
- Centre for Health and Environmental Risk Research, National Institute for Environmental Studies, 16-2 Onogawa, Tsukuba, Japan
| | - Dang Duc Nhu
- Ministry of Health, No 138A Giang Vo, Ba Dinh, Hanoi, Viet Nam
| | - Dao Van Tung
- Viettiep Hospital, No.1 Nha Thuong, Le Chan, Hai Phong, Viet Nam
| | - Vo Van Chi
- Phu Cat Health Centre, No.12, 2/3 St., Ngo May, Phu Cat, Binh Dinh, Viet Nam
| | - Nguyen Hung Minh
- Dioxin Laboratory, Centre for Environment Monitoring, Vietnam Environment Administration, No. 556 Nguyen Van Cu, Long Bien, Hanoi, Viet Nam
| | - Ngo Van Toan
- Ha Noi Medical University, No. 1 Ton That Tung, Dong Da, Hanoi, Viet Nam
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