{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,9,26]],"date-time":"2026-09-26T12:16:35Z","timestamp":1790424995775,"version":"4.1.0"},"reference-count":39,"publisher":"MDPI AG","issue":"6","license":[{"start":{"date-parts":[[2025,6,19]],"date-time":"2025-06-19T00:00:00Z","timestamp":1750291200000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"Ministry of Education, Sports, Science and Culture, Japan","award":["17H04665"],"award-info":[{"award-number":["17H04665"]}]},{"name":"Ministry of Education, Sports, Science and Culture, Japan","award":["18K19709"],"award-info":[{"award-number":["18K19709"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Toxics"],"abstract":"<jats:p>A bioassay for dioxin analysis of human samples has the advantages of cost effectiveness and requiring only a small sample volume. Using a DR-EcoScreen bioassay, we measured the biological equivalency (BEQ) levels in serum samples from 32 men exposed to dioxins in Bien Hoa and 32 unexposed men in Hanoi, Vietnam. For the Bien Hoa men, the World Health Organization toxic equivalent (WHO-TEQ) levels of dioxins had already been measured by instrumental analysis. The difference in fat-based BEQ levels between exposed and unexposed men was greater than for crude BEQ levels, with a strong correlation between fat-based BEQ and WHO-TEQ levels. The fat-based BEQ levels in Bien Hoa men with longer residency but lower WHO-TEQ levels were significantly higher than those in unexposed men and Bien Hoa men with shorter residency but higher WHO-TEQs, suggesting that fat-based BEQ may be an effective marker of dioxin-like activity. Additionally, comparisons of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) and TEQs between shorter- and longer-residency groups indicated that higher levels of polychlorinated dibenzo-p-dioxins (PCDDs), particularly TCDD, contribute to increased BEQ levels. Taken together, the DR-EcoScreen bioassay may be useful to analyze dioxin-like activity associated with WHO-TEQs of men in a dioxin contamination hotspot originating from Agent Orange in Vietnam.<\/jats:p>","DOI":"10.3390\/toxics13060513","type":"journal-article","created":{"date-parts":[[2025,6,19]],"date-time":"2025-06-19T06:11:07Z","timestamp":1750313467000},"page":"513","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":4,"title":["Bioassay Using the DR-EcoScreen System to Measure Dioxin-Related Compounds in Serum Samples from Individuals Exposed to Dioxins Originating from Agent Orange in Vietnam"],"prefix":"10.3390","volume":"13","author":[{"given":"Masafumi","family":"Nakamura","sequence":"first","affiliation":[{"name":"Hiyoshi Corporation, Omihachiman 523-8555, Japan"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Ryo","family":"Matsuda","sequence":"additional","affiliation":[{"name":"Hiyoshi Corporation, Omihachiman 523-8555, Japan"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0009-0002-4863-0653","authenticated-orcid":false,"given":"Hoa Thi","family":"Vu","sequence":"additional","affiliation":[{"name":"Department of Military Hygiene, Vietnam Military Medical University, Hanoi 12108, Vietnam"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-5878-7307","authenticated-orcid":false,"given":"Tai","family":"Pham-The","sequence":"additional","affiliation":[{"name":"Biomedical and Pharmaceutical Research Centre, Vietnam Military Medical University, Hanoi 12108, Vietnam"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Thao Ngoc","family":"Pham","sequence":"additional","affiliation":[{"name":"Department of Functional Diagnosis, Military Hospital 103, Vietnam Military Medical University, Hanoi 12108, Vietnam"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-7979-3813","authenticated-orcid":false,"given":"Tomoya","family":"Takiguchi","sequence":"additional","affiliation":[{"name":"Epidemiology and Public Health, Kanazawa Medical University, Uchinada 920-0293, Japan"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-4786-4610","authenticated-orcid":false,"given":"Hisao","family":"Nishijo","sequence":"additional","affiliation":[{"name":"Department of Sport and Health Sciences, Faculty of Human Sciences, University of East Asia, Shimonoseki 751-8503, Japan"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Muneko","family":"Nishijo","sequence":"additional","affiliation":[{"name":"Epidemiology and Public Health, Kanazawa Medical University, Uchinada 920-0293, Japan"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2025,6,19]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"117","DOI":"10.1016\/S0045-6535(01)00300-9","article-title":"Dioxin reservoirs in southern Viet Nam\u2014A legacy of agent orange","volume":"47","author":"Dwernychuk","year":"2002","journal-title":"Chemosphere"},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"681","DOI":"10.1038\/nature01537","article-title":"The extent and patterns of usage of Agent Orange and other herbicides in Vietnam","volume":"422","author":"Stellman","year":"2003","journal-title":"Nature"},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"998","DOI":"10.1016\/j.chemosphere.2005.01.052","article-title":"Dioxin hot spots in Vietnam","volume":"60","author":"Dwernychuk","year":"2005","journal-title":"Chemosphere"},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"300","DOI":"10.1186\/s40064-015-1064-x","article-title":"Vertical distribution of dioxins in soil of Bien Hoa airbase, Vietnam","volume":"4","author":"Huyen","year":"2015","journal-title":"Springerplus"},{"key":"ref_5","unstructured":"The Office of the Vietnam National Steering Committee 33, and Hatfield Consultants (2011). 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