Objective: The objective of this study was to find sites in Vietnam where there was human exposure from Agent Orange herbicide sprayed between 1962 and 1971, as determined by congener-specific measurement of dioxins, including 2,3,7,8-tetrachlorodibenzodioxin (TCDD), the dioxin that contaminated Agent Orange, in blood. Methods: Blood was collected from residents of eight heavily sprayed regions in the south of Vietnam and analyzed for TCDD and in some cases the dioxin-like dibenzofurans and dioxin-like PCBs. Results: Six of the eight newly studied sites did not show substantial or any elevated TCDD in blood. Marked elevation of TCDD in Vietnamese blood was found in one new location with a suggestion of slightly elevated TCDD in a second location. Conclusions: In newly studied locations in Vietnam, we found some persons with elevation of TCDD consistent with exposure to dioxin from Agent Orange. In our previous studies, we found PCBs, PCDDs, and PCDFs as well as pesticides in human milk, blood, or in food. Health effects from Agent Orange need to be differentiated from effects caused by chemicals other than TCDD from Agent Orange.

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 the TEQ. Thirty-six congeners from 7 classes of chemicals were measured in each of the 16 specimens providing a total of 576 congener levels.

OBJECTIVES:The largest known dioxin contamination occurred between 1962 and 1970, when 12 million gallons of Agent Orange, a defoliant mixture contaminated with a form of the most toxic dioxin, were sprayed over southern and central Vietnam. Studies were performed to determine if elevated dioxin levels persist in Vietnamese living in the south of Vietnam.METHODS:With gas chromatography and mass spectroscopy, human milk, adipose tissue, and blood from Vietnamese living in sprayed and unsprayed areas were analyzed, some individually and some pooled, for dioxins and the closely related dibenzofurans.RESULTS:One hundred sixty dioxin analyses of tissue from 3243 persons were performed. Elevated 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) levels as high as 1832 ppt were found in milk lipid collected from southern Vietnam in 1970, and levels up to 103 ppt were found in adipose tissue in the 1980s. Pooled blood collected from southern Vietnam in 1991/92 also showed elevated TCDD up to 33 ppt, whereas tissue from northern Vietnam (where Agent Orange was not used) revealed TCDD levels at or below 2.9 ppt.CONCLUSIONS:Although most Agent Orange studies have focused on American veterans, many Vietnamese had greater exposure. Because health consequences of dioxin contamination are more likely to be found in Vietnamese living in Vietnam than in any other populations, Vietnam provides a unique setting for dioxin studies.

With substantial improvements in analytic techniques over the past decade, it has become possible to measure polychlorinated dioxins (PCDDs) and dibenzofurans (PCDFs) in human tissue in a congener-specific fashion down to the low parts per trillion level. This paper reviews findings using these new techniques from a number of recent medical and environmental case studies. These studies include those of workers exposed to a polychlorinated biphenyl (PCB) transformer fire in the United States, German chemical workers exposed to 2,3,7,8-tetrachlorodibenzodioxin (2,3,7,8-TCDD) while cleaning up after an explosion, workers at a municipal incinerator in New York City, a chemist exposed to brominated and chlorinated dioxins, U.S. veterans and also Vietnamese civilians exposed to Agent Orange contaminated with TCDD in Vietnam, and victims of the polychlorinated dibenzofuran and PCB contaminated rice oil (Yusho) incident in Japan.

During the past decade a considerable amount of data has been generated concerning polychlorinated dibenzodioxin (PCDD) and polychlorinated dibenzofuran (PCDF) levels in humans from many geographical locations. To organize these data in a useful fashion for environmental purposes and for consideration of human toxicity, selected portions of our data are presented in a somewhat atypical fashion, by percentage contribution of individual congeners to total PCDD/Fs in human tissue, and to the total dioxin equivalents (TEq). This is done to better characterize congener contributions from environmental contamination in various geographical regions at this time and health-related levels. To present the findings in a global perspective, data from widely different locations are presented including the United States, Germany, Vietnam, the former Soviet Union, Thailand, Cambodia, China, South Africa, and Guam.

Soil samples collected randomly from the provinces of Tayninh and Songbe, southwestern Vietnam, were analysed for the presence of DDTs, HCHs and PCBs, Residues of these chemicals were detected in all the analysed samples. Concentrations of SIGMA DDT in cultivated soil samples were relatively high with the highest level of 290 ng/g. However, non-cultivated soil samples recorded lower levels of SIGMA DDT. On the other hand, concentrations of SIGMA HCH were low ranging from 0.09 to 2.3 ng/g in cultivated and from 0.09 to 2.1 ng/g in non-cultivated soils, respectively. Maximum concentrations of PCBs were recorded with the highest level of 150 ng/g in a cultivated soil sample. As for non-cultivated soil samples, the highest level was found in a former U.S. air base grounds. It can then be implied that the PCBs were incorporated in the arms used by allied forces during the Second Indochina War.

Analyses of general population human blood from various geographical locations for polychlorinated dibenzodioxins (PCDD) and polychlorinated dibenzofurans (PCDF) were performed to compare levels of human and environmental contamination at the present time. Pooled or individual samples of blood from adults (usually over the age of 40) were collected in a number of selected locations including St. Petersburg, in western Russia; Baikalsk in Russia's eastern Siberia; and Guam, a South Pacific island. These are compared to previous data from West Germany. America and various locations in Vietnam. Seven hundred and fifty-five blood specimens were collected, 68 from Russia, 10 from Guam, 475 from Vietnam, 102 from Germany and 100 from the USA. Individual dioxin analyses were performed for samples from Guam and Germany; pooled blood was analyzed from the other locations. The German data includes mean, standard deviation, median, and range for each congener; mean values are also presented for Guam and Vietnam.

This paper reports general population blood polychlorinated dioxin and dibenzofuran (PCDD/F) levels for various geographical regions in the north and south of Vietnam in pooled samples from 112 persons, the results of 85 individual analyses of blood from Germany, and levels from a pool of whole blood from 100 U.S. residents. This paper also presents selected population data for PCDD/Fs and certain other chlorinated chemicals such as PCBs and other chlorinated xenobiotics in human milk from locations in Vietnam, Cambodia, and Thailand. These represent new samples from seventy persons from the general population from three less industrialized Asian countries; these are compared with our previous findings from several hundred persons from Germany, the Soviet Union, and the United States.

Sixty patients at hospitals in the north and south of Vietnam had adipose tissue dioxin (TCDD only or PCDD/F) analysis performed, 50 as individual TCDD or PCDD/F analyses, and 10 from the north in a pooled sample analysis. Dibenzodioxin and dibenzofuran adipose tissue levels are usually higher in persons from the south of Vietnam than in persons in the north. There is also a direct correlation between human age and PCDD/F levels. However, dibenzofurans, unlike dioxins, do not differ between persons from the north and south of Vietnam. Vietnam provides an opportunity for human health effects studies of PCDD/F exposure.