Agent Orange Contamination Persists In Vietnam, Study Shows

Toxic byproducts of Agent Orange continue to pollute the environment in Vietnam, say researchers in the US.

AsianScientist (Mar. 12, 2019) – Scientists in the US have demonstrated that a component of Agent Orange used during the Vietnam war continues to contaminate the environment in Vietnam, with implications on health and biodiversity. Their findings are published in the Open Journal of Soil Science.

During the Vietnam War, US aircraft sprayed more than 20 million gallons of herbicides, including dioxin-contaminated Agent Orange, on the country’s rain forests, wetlands and croplands. Agent Orange defoliated the thick jungle vegetation concealing Viet Cong fighters and destroyed a portion of the country’s food crops, but it was primarily the dioxin contaminant that harmed so many Vietnamese and US military personnel.

In this study, scientists at the University of Illinois (UI) and Iowa State University documented the environmental legacy of Agent Orange in Vietnam, including hotspots where dioxin continues to enter the food supply.

“Existing Agent Orange and dioxin research is primarily medical in nature, focusing on the details of human exposure primarily through skin contact and long-term health effects on US soldiers,” said Professor Ken Olson at the Department of Natural Resources and Environmental Sciences at UI and a co-author of the study. “In this paper, we examine the short and long-term environmental effects on the Vietnamese natural resource base and how persistence of dioxin continues to affect soils, water, sediment, fish, aquatic species, the food supply and Vietnamese health.”

The researchers explained that during production of Agent Orange, a toxic byproduct known as dioxin TCDD—the most toxic of the dioxin family of chemicals—is formed. Once dioxin TCDD gets into the environment, it can stick around for decades or even centuries.

The team also traced the path of dioxin TCDD through the ecosystem in Vietnam. The found that the poison is absorbed by tree and shrub leaves, which then drop to the soil surface. The dioxin TCDD then attaches to soil organic matter and clay particles of the soil and moves offsite in surface runoff, clinging to sediment particles and settling in wetlands, marshes, rivers, lakes and ponds.

Dioxin TCDD-contaminated sediment was—and still is—ingested by bottom-feeding fish and shrimp, accumulating in fatty tissue of those animals and up the food chain into many of the fish that form the basis of the Vietnamese diet, the researchers noted. Even though fishing is now banned from most contaminated sites, bans have been difficult to enforce and, as a result, dioxin TCDD is still entering the human food supply 50 years later.

“The worst dioxin-contaminated site in Vietnam is Bien Hoa airbase, which is 30 miles north of Ho Chi Minh City,” said Olsen. “After President Nixon ordered the US military to stop spraying Agent Orange in 1970, this is the site where all the Agent Orange barrels remaining in Vietnam were collected. The barrels were processed and shipped to Johnston Island in the Pacific Ocean, where they were incinerated at sea in 1977.”

Based on their research, the scientists recommend incineration of contaminated soils and sediments at the Vietnam airbase hotspots.

“While incineration is the most expensive technology currently available, it would eliminate dioxin rather than temporarily store it in a landfill, and incineration would not require future maintenance or treatment. Incineration is one of the most commonly used technologies, having been used to treat soils at more than 150 superfund sites, and is a mature and tested technology,” the authors concluded.

The article can be found at: Olson & Morton (2019) Long-Term Fate of Agent Orange and Dioxin TCDD Contaminated Soils and Sediments in Vietnam Hotspots.


Source: University of Illinois; Photo: US Army Flight Operations Specialist 4 John Crivello in 1969.
Disclaimer: This article does not necessarily reflect the views of AsianScientist or its staff.

Asian Scientist Magazine is an award-winning science and technology magazine that highlights R&D news stories from Asia to a global audience. The magazine is published by Singapore-headquartered Wildtype Media Group.

Related Stories from Asian Scientist