AGENT-ORANGE AND THE VIETNAMESE - THE PERSISTENCE OF ELEVATED DIOXIN LEVELS IN HUMAN TISSUES

Objectives. The largest known dioxin contamination occurred between 19 62 and 1970, when 12 million gallons of Agent Orange, a defoliant mixt ure contaminated with a form of the most toxic dioxin, were sprayed ov er southern and central Vietnam. Studies were performed to determine i f 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 s ixty dioxin analyses of tissue from 3243 persons were performed. Eleva ted 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. Po oled blood collected from southern Vietnam in 1991/92 also showed elev ated TCDD up to 33 ppt, whereas tissue from northern Vietnam (where Ag ent Orange was not used) revealed TCDD levels at or below 2.9 ppt. Con clusions. Although most Agent Orange studies have focused on American veterans, many Vietnamese had greater exposure. Because health consequ ences of dioxin contamination are more likely to be found in Vietnames e living in Vietnam than in any other populations, Vietnam provides a unique setting for-dioxin studies.