Dioxin, dibenzofuran, and polychlorinated biphenyl (PCB) levels in food from Agent Orange-sprayed and nonsprayed areas of Laos

During the Vietnam War, a phenoxy-herbicide mixture called Agent Orange, which was contaminated with 2,3,7,8-tetrachlorodibenzodioxin, or TCDD, was used primarily for destruction of forest and other foliage in order to prevent enemy troop movement and protect American and allied troops and military bases in the south of Vietnam. Smaller areas of Laos and Cambodia were also sprayed with Agent Orange between 1962 and 1971 from fixed-wing aircraft. In 2001, 28 food samples consisting of meat, fish, and dairy products were collected in sprayed and nonsprayed areas of Laos and analyzed for dioxins, dioxinlike dibenzofurans, and selected polychlorinated biphenyl (PCB) congeners by high-resolution gas chromatography/high-resolution mass spectrometry at laboratories in Germany and Canada. Low levels of dioxin and other dioxinlike substances were found in Laotian food, similar to levels present in recent exported Vietnamese food to United States. Vietnam is geographically adjacent to Laos. Total dioxin toxic equivalent (TEQ) levels were similar in samples from sprayed and non-sprayed areas, ranging from 0.009 to 0.851 pg/g or parts per trillion (ppt) in sprayed Sepone, and from 0.022 to 0.537 pg/g or ppt wet weight in non sprayed Vientiane. However, the Laotian fish samples from the Agent Orange-sprayed area had, on average, a higher proportion of total TEQ from TCDD (31.7% vs. 9.4%) compared to the nonsprayed area. Some other food items, duck eggs and pork liver from Sepone, also had severalfold higher TCDD levels than similar food samples from Vientiane, 0.029 vs. 0.011 pg/g and 0.070 vs. 0.004 pg/g wet weight, respectively. There were no substantial differences in levels of dibenzofuran and PCB congeners. In general, elevated TCDD levels were not found in Laotian food samples. It is possible that dioxin-contaminated areas, or "hot spots," exist in Laos as they do in Vietnam, although they have not yet been identified.