THE UNITED STATES today began a landmark project to clean up a dangerous chemical left from the defoliant Agent Orange — 50 years after it was first sprayed by American planes on Vietnam’s jungles to destroy enemy cover.

Dioxin, which has been linked to cancer, birth defects and other disabilities, will be removed from the site of a former US air base in Danang in central Vietnam. The effort is seen as a long-overdue step toward removing a thorn in relations between the former foes nearly four decades after the Vietnam War ended.

“We are both moving earth and taking the first steps to bury the legacies of our past,” US Ambassador David Shear said during the groundbreaking ceremony near the area where a rusty barbed wire fence marks the site’s boundary. “I look forward to even more success to follow.”

The $43 million joint project with Vietnam is expected to be completed in four years on the 19-hectare contaminated site, located near Danang’s commercial airport and an active Vietnamese military base.

Washington has been slow to respond, quibbling for years over the need for more scientific research to show that the herbicide caused health problems and birth defects among Vietnamese. It has given about $60 million for environmental restoration and social services in Vietnam since 2007, but this is its first direct involvement in cleaning up dioxin, which has seeped into Vietnam’s soil and watersheds for generations.

October, 2009: Tran Thi Gai, 45, comforts her daughter Nguyen Thi Tai, 21, while her youngest daughter Nguyen Thi Thuyet, 16, lies next to them on a bed in the village of Cam Tuyen, Vietnam. The two young women were born with profound physical and mental disabilities that the family and local officials say were caused by their parents’ exposure to Agent Orange. (AP Photo/David Guttenfelder/PA)

Shear added the US is planning to evaluate what’s needed for remediation at the former Bien Hoa air base in southern Vietnam, another Agent Orange hotspot.

The remediation begins as Vietnam and the US forge closer ties to boost trade and counter China’s rising influence in the disputed South China Sea that’s believed rich in oil and natural resources. The US says protecting peace and freedom of navigation in the sea is in its national interest.

Defoliant

The Danang site is closed to the public. Part of it consists of a dry field where US troops once stored and mixed the defoliant before it was loaded onto planes. The area is ringed by tall grass and a faint chemical smell could be detected during a visit to the area Thursday.

The contaminated area also includes lakes and wetlands dotted with pink lotus flowers where dioxin has seeped into soil and sediment over decades. A high concrete wall separates it from nearby communities and serves as a barrier to keep residents from fishing in the tainted water.

The US military dumped some 20 million gallons of Agent Orange and other herbicides on about a quarter of former South Vietnam between 1962 and 1971, decimating about 2 million hectares of forest — roughly the size of Massachusetts.

Maps of the area contaminated with dioxin around Danang airport, a former US military base in Vietnam. Dioxin can linger in soils and at the bottom of lakes and rivers for generations, entering the food supply through the fat of fish and other animals. (AP Photo/Maika Elan/PA)

The war ended on April 30, 1975, when northern Communist forces seized control of Saigon, the US-backed capital of former South Vietnam. Some 58,000 Americans died, along with an estimated 3 million Vietnamese. The country was then reunified under a one-party Communist government. Following years of poverty and isolation, Vietnam shook hands with the US in 1995 and normalised diplomatic relations.

The Agent Orange issue has continued to blight the US-Vietnam relationship because dioxin can linger in soils and at the bottom of lakes and rivers for generations, entering the food supply through the fat of fish and other animals.

Although the chemical remains at the Danang site, US officials said today that containment measures implemented in recent years temporarily ended the public health threat to the local community.

In 2007, Vietnamese authorities — with technical assistance from the US Environmental Protection Agency and funding from the nonprofit US-based Ford Foundation — poured a 6-inch concrete slab half the size of a football field over the contaminated area where Agent Orange was mixed. Dioxin is not water-soluble and only spreads when rainfall and runoff move contaminated mud.

Vietnam’s Ministry of Defense and the US now plan to excavate 73,000 cubic metres employing technology used to clean superfund sites in the US.

Workers will first dig down about 2 metres. The soil will then be heated to 335°C in special containers where the dioxin will break down into oxygen, carbon dioxide and other substances that pose no health risks to humans or animals.

Vietnam’s deputy defense minister, Nguyen Chi Vinh, said Thursday he hopes to receive more support from the international community and the US government to help remediate dioxin hotspots elsewhere across the country. The former US air base in southern Phu Cat has already been identified, but he said many dioxin-contaminated areas in Vietnam have not been adequately assessed.

It is still unclear how much the US will help clean up in the long term and how much it will allocate for people who claim to be Agent Orange victims.