Food as a Source of Dioxin Exposure in the Residents of Bien Hoa City, Vietnam

Abstract

Recently, elevated dioxin levels, over 5 parts per trillion (ppt) 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), from Agent Orange was reported in 95% of 43 selected residents of Bien Hoa City, a city in southern Vietnam near a former air base used for Agent Orange-spraying missions. Agent Orange herbicide, contaminated with TCDD, was sprayed in Vietnam between 1962 and 1971 primarily for use as a defoliant. Typical blood TCCD levels are 2 ppt in Vietnamese, but levels are as high as 413 ppt in Bien Hoa City. Elevated TCDD was found in children born many years after Agent Orange spraying ended and in immigrants from non-Agent Orange-sprayed parts of Vietnam, which documented new exposures. Extremely elevated soil TCDD samples, over 1 million ppt, and elevated TCDD in sediment were found in some nearby areas such as Bien Hung Lake. The primary route of intake of almost all dioxins in humans is food. However, in our prior studies in Bien Hoa, food was unavailable for dioxin analysis so the route of intake was not confirmed. In the 1970s, while Agent Orange was still being sprayed, elevated human milk TCDD levels as high as 1850 were detected in milk from Vietnamese people living in Agent Orange-sprayed areas where consumption of fish was high. Furthermore, also in the 1970s, elevated TCDD levels (up to 810 ppt) were found in fish and shrimp from the same area as the milk donors. In the 1980s, we found elevated TCDD and also other organohalogen levels in human tissue, pork, fish, a turtle, and a snake in Southern Vietnam. For these reasons, we recently collected food from Bien Hoa and analyzed it for dioxins, polychlorinated biphenyls (PCBs), DDT and its metabolites, and other organochlorines. We found marked elevation of TCDD, the dioxin characteristic of Agent Orange, in some of the food products, including ducks with 276 ppt and 331 ppt wet weight, chickens from 0.031-15 ppt wet weight, fish from 0.063-65 ppt wet weight, and a toad with 56 ppt wet weight. Usual TCDD levels in food are less than 0.1 ppt. Total TEQ for ducks was from 286-343 ppt wet weight or 536 ppt and 550 ppt lipid; for chickens from 0.35-48 ppt wet weight or 0.95-74 ppt lipid, for fish from 0.19-66 ppt wet weight or 3.2 ppt and 15,349 ppt lipid, and the toad was 80 ppt wet weight and 11,765 ppt lipid. Interestingly, this study did not find elevated levels of TCDD in the pork and beef samples. Clearly, food, including duck, chicken, some fish, and a toad, appears responsible for elevated TCDD in residents of Bien Hoa City, even though the original Agent Orange contamination occurred 30-40 years before sampling. Elevated levels of PCBs and DDT and its metabolites were found in some food samples. Furthermore, measurable levels of hexachlorocyclohexanes (HCH) and hexachlorobenzene (HCB) were found in a wide range of measurable levels. All of the 11 dioxin-like PCBs measured and presented plus 6 dioxins in addition to TCDD and 10 dibenzofurans contributed to the total dioxin toxicity (TEQ). However, when elevated, TCDD frequently contributed most of th...

Levels of polychlorinated dibenzodioxins and polychlorinated dibenzofurans in breast milk samples from three dioxin-contaminated hotspots of Vietnam

“…Furthermore, food collected from local markets in Bien Hoa City showed high TCDD levels in fat samples from duck (536-550 ppt lipid), chicken (0.95-74 ppt lipid), and fish (3.2-15349 ppt lipid). These authors suggested that Bien Hoa air base was the origin of this TCDD (Schecter et al, 2003). Our current study, carried out at Bien Hoa air base nearly one decade later, showed lower TCDD levels in human breast milk as compared with those in blood samples reported by Schecter et al (2001).…”

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

“…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).…”

PCDD/Fs in sediments of Central Vietnam coastal lagoons: In search of TCDD

“…Moreover, elevated TCDD levels were measured also in the components of the human food chain (i.e. environmental matrices and living organisms that form the food chain where humans are the ultimate consumers; Dwernychuk et al, 2002), food and wildlife (Olie et al, 1989), as well as in people from the most contaminated areas (Schecter et al, 2001(Schecter et al, , 2002(Schecter et al, , 2003Dwernychuk et al, 2002), in accordance with the general population's route of exposure that proceeds almost exclusively through consumption of animal foods, including meat, fish, and dairy products (Startin and Rose, 2003;EPA, 2004).…”

“…These are important and good news for people living close to these water bodies. However, the problem of PCDD/F contamination remains relevant for those places, such as the A Luoi valley, that formerly hosted several US bases but are now occupied by villages, where civilians live and extensively rework the contaminated soils for agricultural purposes, as testified by a considerable amount of literature (Olie et al, 1989;Schecter et al, 2001Schecter et al, , 2002Schecter et al, , 2003Dwernychuk et al, 2002;Scott-Clark and Levy, 2003;Stellman et al, 2003;Young et al, 2004;Mai et al, 2007). This is likely affecting TCDD levels in food from this region and the eastern watershed that feeds the Mekong River, but not the southeastern coastal locations object of the present study.…”