In a photo from 2011, Le Thi Mit feeds her son Lanh, then 26, at their home in Cam Lo , Vietnam. (Paula Bronstein/Getty Images)

When Le Thi Mit is awakened at night by the moans of her 34-year-old son, she thinks back half a century, grappling with the vivid memories of American planes flying overhead to coat her village with toxic chemicals.

Three of her four children were born severely disabled. One died young. Truong, 28, who crawls because his sticklike legs cannot support him, cannot speak, bathe himself or eat on his own. Lanh, the 34-year-old, is confined to a bed of wooden slats by his gnarled back.

Mit’s wish is that her children die first. There is no one else to care for them.

As President Obama is scheduled to visit in May amid warming relations between the former foes, the United States has increased its commitment to heal lingering wounds from Agent Orange and other jungle-clearing defoliants it deployed during the Vietnam War.

A $100 million experiment to eliminate a dioxin “hot spot” in Da Nang is only the beginning of a vast environmental cleanup. But the U.S. government has spent far less on helping victims, reluctant to wade into the legal and political minefield of Agent Orange in part because of a lack of definitive science.

For decades, American officials minimized or dismissed Vietnam’s health problems. Vietnamese officials also skirted the issue at times out of concern for the image of the country’s agricultural exports.

But the United States is gradually increasing its victim funding, and both governments now willingly speak about Agent Orange. Congress allocated $7 million this year to health and disability programs in Vietnam, much of it targeting presumed Agent Orange victims.

“We are not aware of any widely accepted scientific study that conclusively establishes a connection between dioxin and these types of physical or psychological disabilities,” said Tim Rieser, a longtime foreign policy aide to Sen. Patrick J. Leahy (D-Vt.), who has led the charge to appropriate money for Agent Orange. But “the United States is essentially acknowledging by our actions that there is likely a causal effect, and Senator Leahy believes we have a responsibility to help address it.”

A country poisoned

In places such as Cam Lo, a heavily sprayed area near the demilitarized zone where birth defects surged after the war, nongovernmental organizations and foreign governments have stepped in to ease the burden on Agent Orange families, who also get small payments from the Vietnamese government.

Many activists contend the United States is shirking true responsibility.

“The U.S. government is never going to step up on Agent Orange,” said Suel Jones of Veterans for Peace. Jones fought in Vietnam as a Marine then returned to work with war victims. “It opens them up to a moral responsibility. Say what we want to say, but we sprayed poison on this damned country.”

U.S. forces sprayed 21 million gallons of defoliants on southern Vietnam from 1961 to 1971, including 12 million gallons of Agent Orange, to deny its enemies cover and kill food crops. Though service members and the public were told the chemicals were harmless to humans, Agent Orange was contaminated with dioxin, a highly toxic chemical.

Through direct contact, or from eating food raised or grown in contaminated areas, thousands of Americans and millions of Vietnamese were exposed to dioxin. There is no treatment for it.

As a result of a 1991 law, the Department of Veterans Affairs provides benefits to service members who came in contact with Agent Orange and now suffer from cancer, diabetes or other ailments.

Vietnamese do not get the same compensation. Vietnamese victims sued the chemical companies that manufactured the herbicides, but the case was dismissed in U.S. courts. Another suit is pending in France.

Scientific proof of physical impairments linked to the American spraying — which could lead to legal liability — would be difficult and expensive to come by in a developing nation where other environmental factors could contribute to dioxin poisoning. Doctors here do not tend to diagnose specific birth defects such as spina bifida or cerebral palsy, often just assuming disabled children in certain areas are Agent Orange victims. Vietnamese advocacy groups estimate that 3 million people suffer from health problems related to Agent Orange.

The giant ‘oven’

While most dioxin has dissipated over the years, a Canadian research firm identified three major hot spots where Agent Orange was stored and contamination lingers. Another two dozen potential hot spots dot the country.

The Da Nang air base is the first to be cleaned up, under a joint venture launched in 2012 by the U.S. Agency for International Development and the Vietnamese government.

As jets from the adjacent commercial airport take off overhead, men in hazmat suits carefully haul contaminated soil into a large heating structure. Once a load has 45,000 cubic meters of dirt — a football field filled two stories high — the “oven” is enclosed with concrete blocks.

Then they turn up the heat. Over months, the soil is heated to a minimum of 635 degrees throughout the pile. The extreme heat neutralizes nearly all the contaminants in the soil, which will be used to build a new runway for private jets.

The project was intended to cost $43 million and finish this year, but breakdowns and delays have pushed the cost to upward of $100 million and the end date to 2018.

USAID and project managers say the first of two rounds of heating successfully treated the dioxin. The next stop is the biggest Agent Orange storage site, the Bien Hoa air base near Ho Chi Minh City, where cleanup could cost $250 million and take more than a decade.

The human toll is harder to quantify.

In Da Nang, residents were still fishing out of a contaminated lake as recently as 2012 when the airport cleanup began, and there are thousands of assumed victims in the area.

On the edge of town at a victims center funded by foreign donors, children and adults with limited mental capacity play in classrooms, while those with more severe disabilities lie in a hospital ward. In many cases the contamination began with their grandparents.

“A nuclear bomb that is dropped, it kills a person. They die. It’s finished,” said Nguyen Thi Hien, who runs the center. “But this is lasting over three or four generations.”

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