Dioxin reservoirs in southern Viet Nam—A legacy of Agent Orange

Dwernychuk, L. Wayne; Cau, Hoang Dinh; Hatfield, Christopher T.; Boivin, Thomas G.; Hung, Tran Manh; Dung, Phung Tri; Thái, Nguyễn Đình

doi:10.1016/s0045-6535(01)00300-9

Cited by 108 publications

(78 citation statements)

References 41 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…For the remaining 22 patients, the Pearson correlation coefficient was 0.50 for association between the log of serum dioxin and log of the EOI (P ¼ 0.02) and the Spearman correlation coefficient was 0.44 (P ¼ 0.04) (Verger et al, 1994). Besides this quantitative validation, a qualitative concordance has been observed between extremely high dioxin concentrations in samples of soil taken at an abandoned US air base in the Ashau valley, as reported by Dwernychuk et al (2002) and the HERBS file locations of spraying of Agent Purple at that location. Agent Purple was an early herbicide whose dioxin contamination was estimated at 10-100 times that of Orange (Stellman et al, 2003a).…”

Section: Validitysupporting

confidence: 69%

“…Recent surveys in Vietnam by Dwernychuk et al (2002), Schecter et al (2001), and others have shown persistently high levels of dioxin in soil, biota, and humans taken from areas known to have been very heavily sprayed or contaminated by spillage. In March 2002, the United States and the government of Vietnam entered into a collaborative agreement to undertake future epidemiological and ecological studies of the effects of wartime herbicide use in that country (Cyranoski, 2002).…”

Section: Limitationsmentioning

confidence: 99%

“…(National Research Council, 1974;Institute of Medicine, 1994, 2001. Persistently high levels of dioxins in Vietnam soil and biota, as well as in samples of Vietnamese serum, adipose tissue, and breast milk have been reported and so-called ''hot spots'' identified (Dwernychuk et al, 2002). The military use of herbicides in Vietnam thus represents one of the most concentrated environmental exposures to dioxin-contaminated herbicides for which few systematic investigations of health and ecological effects have been carried out.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Exposure opportunity models for Agent Orange, dioxin, and other military herbicides used in Vietnam, 1961–1971

Stellman

2004

J Expo Sci Environ Epidemiol

View full text Add to dashboard Cite

Nearly 19.5 million gallons of herbicides were sprayed on the Republic of Vietnam between 1961 and 1971 for military purposes. Amounts of spray and patterns of applications are available in an electronic file called HERBS that contains records of 9141 defoliation missions, including detailed coordinates of US Air Force Ranch Hand aircraft flight paths, along with chemical agent and gallonage sprayed. Two classes of models for use in epidemiological and environmental studies that utilize the HERBS data for estimating relative exposure opportunity indices are presented: a discrete ''hits'' model that counts instances of proximity in time and space to known herbicide applications, and a continuous exposure opportunity index, E4, that takes into account type and amount of herbicide sprayed, distance from spray application, and time interval when exposure may have occurred. Both direct spraying and indirect exposure to herbicide (or dioxin) that may have remained in the local environment are considered, using a conservative first-order model for environmental disappearance. A correction factor for dermal versus respiratory routes of entry has been incorporated. E4 has a log-normal distribution that spans six orders of magnitude, thus providing a substantial amount of discrimination between sprayed and unsprayed areas. The models improve on earlier ones by making full use of the geometry of the HERBS spray flight paths of Ranch Hand aircraft. To the extent possible so many decades after the War, the models have been qualitatively validated by comparison with recent dioxin soil and biota samples from heavily contaminated areas of Vietnam, and quantitatively validated against adipose dioxin obtained in epidemiological studies of Vietnamese. These models are incorporated within a geographic information system (GIS) that may be used, as one would expect, to identify locations such as hamlets, villages, and military installations sprayed by herbicide. In a novel application, the GIS also facilitates quantitative risk assessment in epidemiological and ecological studies by applying the models within a framework of historical reconstruction of exposure history of individuals based upon their location histories.

show abstract

Section: Validitysupporting

confidence: 69%

Section: Limitationsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Exposure opportunity models for Agent Orange, dioxin, and other military herbicides used in Vietnam, 1961–1971

Stellman

2004

J Expo Sci Environ Epidemiol

View full text Add to dashboard Cite

show abstract

“…As herbicides are known to have been spilled at those sites where soil and sediment dioxin levels are found to be high, individuals residing close to these sites are highly likely to have been exposed to such levels (Dwernychuk 2005;Dwernychuk et al 2006). Indeed, previous studies detected elevated TCDD levels in food, wildlife, and subjects from a contaminated area (Schecter et al 2001(Schecter et al , 2002(Schecter et al , 2003Dwernychuk et al 2002). Furthermore, studies recently demonstrated that the mean dioxin levels in soil and breast milk in a sprayed area are significantly higher than those in a non-sprayed area (Nhu et al 2009;Saito et al 2010).…”

Section: Introductionmentioning

confidence: 99%

Dioxin levels in the breast milk and estradiol and androgen levels in the saliva of Vietnamese primiparae

Nhu

Kido

Hưng

et al. 2011

Toxicological & Environmental Chemistry

View full text Add to dashboard Cite

Human exposure to polychlorinated dibenzodioxins (PCDD) and dibenzofurans (PCDF), especially 2,3,7,8 tetrachlorodibenzo-p-dioxin (TCDD), was investigated in Vietnam since initial severe adverse health effects were reported in the late 1970s. The purpose of this study was to determine the effects of dioxin exposure on steroid hormones of primiparae in an Agent Orange/dioxin hot-spot and a non-exposed area in Vietnam. Sixteen primiparae (8 at each site), all of whom were aged between 20 and 30 years with infants aged between 4 and 16 weeks, agreed to participate in this study. The mean dioxin levels in breast milk of primiparae from the hot-spot area, in terms of PCDD, PCDF, and PCDD þ PCDF toxic equivalents (TEQ), were significantly higher than those for the non-exposed area. PCDD TEQ, PCDF TEQ, and PCDD þ PCDF TEQ levels showed a significant correlation with dehydroepiandrosterone (DHEA), androstenedione (A-dione), and estradiol (E2) in the saliva of primiparae in a combination of hot-spot and non-exposed areas in Vietnam. The dose-response curve between salivary E2 or A-dione levels and dioxin levels was U-shaped in humans. This study provides an overview of studies regarding dioxin hot-spots and effects on human health and steroid hormone levels in particular, with a focus on the toxicity attributed to dioxins and furans. Furthermore, causal evidence regarding the effects of dioxins on endocrine disruption in humans is provided.

show abstract

“…The Bien Hoa airbase was the major staging point for the Operation ‘Ranch Hand’ in South Vietnam and served as storage site for the barrels containing the herbicides. Large spills during handling led to a high herbicide and dioxin contamination of soils and sediments in the vicinity of Bien Hoa (Dwernychuk et al ., 2002; Mai et al ., 2007). An active landfill (3384 m 3 of herbicide‐ and dioxin‐contaminated soil subdivided into the four bioremediation cells BH1‐BH4) was established and operated for 40 months (Dang and Nguyen, 2012).…”

Section: Introductionmentioning

confidence: 99%

Desulfitobacterium contributes to the microbial transformation of 2,4,5‐T by methanogenic enrichment cultures from a Vietnamese active landfill

Lechner

Türkowsky

Dinh

et al. 2018

Microbial Biotechnology

View full text Add to dashboard Cite

SummaryThe herbicide 2,4,5‐trichlorophenoxyacetic acid (2,4,5‐T) was a major component of Agent Orange, which was used as a defoliant in the Vietnam War. Little is known about its degradation under anoxic conditions. Established enrichment cultures using soil from an Agent Orange bioremediation plant in southern Vietnam with pyruvate as potential electron donor and carbon source were shown to degrade 2,4,5‐T via ether cleavage to 2,4,5‐trichlorophenol (2,4,5‐TCP), which was further dechlorinated to 3,4‐dichlorophenol. Pyruvate was initially fermented to hydrogen, acetate and propionate. Hydrogen was then used as the direct electron donor for ether cleavage of 2,4,5‐T and subsequent dechlorination of 2,4,5‐TCP. 16S rRNA gene amplicon sequencing indicated the presence of bacteria and archaea mainly belonging to the Firmicutes, Bacteroidetes, Spirochaetes, Chloroflexi and Euryarchaeota. Desulfitobacterium hafniense was identified as the dechlorinating bacterium. Metaproteomics of the enrichment culture indicated higher protein abundances of 60 protein groups in the presence of 2,4,5‐T. A reductive dehalogenase related to RdhA3 of D. hafniense showed the highest fold change, supporting its function in reductive dehalogenation of 2,4,5‐TCP. Despite an ether‐cleaving enzyme not being detected, the inhibition of ether cleavage but not of dechlorination, by 2‐bromoethane sulphonate, suggested that the two reactions are catalysed by different organisms.

show abstract

Dioxin reservoirs in southern Viet Nam—A legacy of Agent Orange

Cited by 108 publications

References 41 publications

Exposure opportunity models for Agent Orange, dioxin, and other military herbicides used in Vietnam, 1961–1971

Exposure opportunity models for Agent Orange, dioxin, and other military herbicides used in Vietnam, 1961–1971

Dioxin levels in the breast milk and estradiol and androgen levels in the saliva of Vietnamese primiparae

Desulfitobacterium contributes to the microbial transformation of 2,4,5‐T by methanogenic enrichment cultures from a Vietnamese active landfill

Contact Info

Product

Resources

About