Recent Dioxin Contamination From Agent Orange in Residents of a Southern Vietnam City

Abstract

Marked elevation of dioxin associated with the herbicide Agent Orange was recently found in 19 of 20 blood samples from persons living in Bien Hoa, a large city in southern Vietnam. This city is located near an air base that was used for Agent Orange spray missions between 1962 and 1970. A spill of Agent Orange occurred at this air base more than 30 years before blood samples were collected in 1999. Samples were collected, frozen, and sent to a World Health Organization--certified dioxin laboratory for congener-specific analysis as part of a Vietnam Red Cross project. Previous analyses of more than 2200 pooled blood samples collected in the 1990s identified Bien Hoa as one of several southern Vietnam areas with persons having elevated blood dioxin levels from exposure to Agent Orange. In sharp contrast to this study, our previous research showed decreasing tissue dioxin levels over time since 1970. Only the dioxin that contaminated Agent Orange, 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), was elevated in the blood of 19 of 20 persons sampled from Bien Hoa. A comparison, pooled sample from 100 residents of Hanoi, where Agent Orange was not used, measured blood TCDD levels of 2 parts per trillion (ppt). TCDD levels of up to 271 ppt, a 135-fold increase, were found in Bien Hoa residents. TCDD contamination was also found in some nearby soil and sediment samples. Persons new to this region and children born after Agent Orange spraying ended also had elevated TCDD levels. This TCDD uptake was recent and occurred decades after spraying ended. We hypothesize that a major route of current and past exposures is from the movement of dioxin from soil into river sediment, then into fish, and from fish consumption into people.

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

“…Several studies reported that the half-life of dioxin in humans is 7-11 years for adults (Pirkle et al 1989;Kreuzer et al 1997). Despite the fact that a significant amount of time has passed since the end of the war, herbicide residues still exert adverse effects on those subjects living in the sprayed/hot-spot areas and on the country's ecosystem as a whole (Schecter et al 2001;Mai et al 2007). Dioxin hot-spots contain high TCDD levels due to the inevitable spillages that occurred during loading of the herbicide into crop-spraying planes during the Vietnam War (Dwernychuk 2005), and our study showed that mean dioxin levels in breast milk of primiparas were higher in the hot-spot than in the nonsprayed area.…”

“…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).…”

Characterization of dioxin exposure in residents of Chapaevsk, Russia

“…In comparison to other industrialized countries, the dioxin burden in Chapaevsk residents was also substantially higher than general population levels reported for North America ( Longnecker et al, 2000;Schecter et al, 2002 ), Germany ( the 1996 data ) (Päpke, 1998 ), and Hanoi, Vietnam (Schecter et al, 2001 ). On the contrary, mean WHO -TEQ 98 levels of 2,3,7,8 -TCDD in Chapaevsk residents (8.3 ppt ) were lower, as compared to populations with known high 2,3,7,8 -TCDD exposure, such as South Vietnam residents exposed to Agent Orange ( 69.7 ppt ) (Schecter et al, 2001 ) and residents of the most contaminated zone in Seveso, Italy (53.2 ppt ) ( Landi et al, 1997 ). Goldman et al (2000 ) reported serum PCDD /PCDFs levels for California residents living in close proximity to a wood preservative treatment plant, where there had been a fire involving pentachlorophenol.…”

“…Chapaevsk residents extensively use these areas as garden plots for food production, which is often sold at the local market. Table 4 presents the mean dioxin WHO -TEQ 98 levels in serum of Chapaevsk residents in comparison to reported levels in workers and general population samples from other parts of Russia, North America, Europe, and Asia ( Päpke, 1998;Longnecker et al, 2000;Ryan and Schecter, 2000;Amirova and Kruglov, 2001;Amirova et al, 1998;Revich et al, 2001;Schecter et al, 2001Schecter et al, , 2002. For comparison purposes, previously published data on dioxin TEQ exposure from Russia and other countries, which used the 1994 I -TEFs ( Ahlborg et al, 1994 ), were recalculated using the 1998 WHO -TEFs ( Van den Berg et al, 1998 ).…”

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

“…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).…”