(AP) -- New environmental tests confirm extremely high levels of dioxin, the toxic ingredient of Agent Orange, in people, fish and soil near a former U.S. air base where American troops stored the herbicide during the Vietnam War.
"Time is of the essence" to finish cleaning up the site, now home to the Danang airport, where dioxin levels in the soil, sediment and fish were 300 to 400 times higher than internationally accepted levels, the survey by the Canadian environmental firm Hatfield Consultants said.
The survey also found that temporary containment measures jointly implemented by the U.S. and Vietnam in 2007 have apparently resulted in lower dioxin levels in people who live near the site.
Agent Orange is perhaps the war's most contentious legacy. Vietnam says 1 million to 4 million of its citizens were exposed to it and many suffered serious health consequences. The United States, which sprayed the herbicide on jungles to deprive Vietnamese troops of ground cover, says further scientific study is needed to fully understand the health links.
The new survey was shared this week with members of a joint U.S.-Vietnam advisory committee on Agent Orange, which held its fourth annual meeting in Hanoi this week.
The Associated Press obtained a copy. The firm released the findings to Vietnamese officials on Friday. Vietnamese officials declined to comment, and US officials could not be reached.
"Dioxin levels at this location continue to exceed all international standards and guidelines for these toxic chemicals," said Thomas Boivin, president of Hatfield, which conducted the study with the Vietnamese government.
The survey said dioxin poses a potential health risk to roughly 100,000 people who live in neighborhoods next to the airport, but it poses no immediate threat to the vast majority of the city's nearly 1 million people or the Danang International Airport terminal, which sits on the sprawling site.
Hatfield first conducted tests at the site in 2006, but took another round of samples earlier this year after learning that Agent Orange had been stored in a section of the airport that had previously been untested.
The study was funded by the Ford Foundation and commissioned by Vietnamese environmental officials, who are working with their American counterparts to address the environmental and health effects of dioxin at several Agent Orange "hotspots" in Vietnam.
After years of disagreement, the two sides began working together in 2006 to address problems linked to the herbicide, and they began their efforts in Danang.
The Hatfield study found that people who work at the Danang airport or eat fish from lakes near the former Agent Orange storage sites were the most likely to have elevated dioxin levels in their blood.
In all, Hatfield took 410 samples of soil, sediment and fish at the Danang site, as well as 171 samples of human blood and breast milk from people who live near it.
The results showed about 50 people who previously lived on the site and ate fish from a contaminated lake there had extraordinarily high levels of dioxin.
People who live in neighborhoods adjacent to the airport also had elevated dioxin levels but not nearly as high as those who lived on the site, the study found.
Two years ago, Vietnamese officials warned people to stop fishing at the Danang site.
Dioxin attaches itself to soil and sediment and remains in the environment for generations. Although not absorbed by crops such as rice, it concentrates in the fat of fish and other animals that ingest it and can be passed to humans through the food chain.
Earlier tests by Hatfield showed that dioxin levels were safe across most of Vietnam with the exception of about a half-dozen Agent Orange hotspots where U.S. troops used to mix, store and load Agent Orange onto planes.
The Hatfield report said Agent Orange areas at former air bases in Bien Hoa and Phu Cat also require cleanup.
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