Dioxin from Agent Orange, sprayed by the US military during the Vietnam war, is still poisoning Vietnamese people today, 30-40 years after spraying ended, says Dr Arnold Schecter of the University of Texas School of Public Health, Dallas.
Figure 1.
Hanoi market trader: duck is considered a delicacy
Credit: MARK HENLEY/PANOS
He, along with an international research team, collected samples of animals used for food from Bien Hoa City, 35 kilometres north of Ho Chi Minh City (formerly Saigon). Results of their study are reported in the August issue of the Journal of Occupational and Environmental Medicine (2003;45: 781-8).
“Even in children never sprayed with Agent Orange, dioxin is getting into the Vietnamese people through highly contaminated foods, including duck, chicken, and fish,” said Dr Schecter.
The Agent Orange herbicide, containing tetrachlorodibenzop-dioxin (TCDD), was sprayed in Vietnam between 1962 and 1971, primarily as a defoliant. Typical blood concentrations of TCDD among Vietnamese people are 2 ppt (parts per trillion), but concentrations as high as 413 ppt were found in Bien Hoa City.
High TCDD concentrations were found in children born many years after spraying with Agent Orange ended and in migrants from parts of Vietnam where Agent Orange wasn't sprayed. Extremely high concentrations in soil samples—over 1 million ppt—and in sediment were found in some nearby areas, such as Lake Bien Hung.
Usual TCDD concentrations in food are less than 0.1 ppt, yet the researchers found concentrations in ducks up to 331 ppt wet weight, in chickens up to 15 ppt wet weight, and in fish up to 66 wet weight, or 550 ppt in lipids.
High concentrations of polychlorinated biphenyls (PCBs) of unknown source and dicophane (DDT) and its metabolites were found in some food samples, and a wide range of measurable levels of hexachlorocyclohexanes and hexachlorobenzene were found.
The highest concentrations of TCDD were found in the fat of tested animals—an important finding, because fat is considered a delicacy in Vietnam.
Dr Schecter said that although most food in Vietnam is not contaminated with dioxins, certain dioxin “hot spots” are highly contaminated, and the high PCB concentrations add to the toxicity of TCDD. In 1971 a spill from underground storage tanks at an airbase near Bien Hoa City released thousands of litres of Agent Orange into the environment.
To help people in Bien Hoa City and other hot spots, Dr Schecter and colleagues recommend measures to supply uncontaminated food, along with additional healthcare follow up and possible methods of environmental restoration. They also urge further studies of the effects on health of dioxins and other toxic chemicals among veterans who served in the Vietnam war.
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