Welsh photographer Philip Jones Griffiths first heard about the dangers of Agent Orange (the highly toxic herbicide used as a defoliant during the Vietnam War) in Saigon in 1967. “During the war there were these rumours that babies were being born without eyes and it became a quest to find them,” says Griffiths. “I visited as many catholic orphanages as I could, but I was barred entry from most of them and I became convinced that the Americans had put the word out – don’t let any press in.”

After the publication of Vietnam Inc. (Griffiths’ book on the failings of the American war machine) in 1971, Griffiths was banned from re-entering Vietnam. He didn’t return until 1980, when he met victims of Agent Orange for the first time. Over the next 20 years, he would photograph some of Vietnam’s estimated 1 million victims, building a body of work now published as Agent Orange, a harsh and uncompromising examination of the legacy left by US chemical spraying of the Vietnamese landscape.

Griffiths first encounter with Agent Orange victims happened almost by chance. “We were travelling by road from Hanoi to Saigon and we started talking about Agent Orange. The driver said, well there’s this family with two blind daughters – we’ll probably see them tomorrow.”

“It was very emotional. The husband had been a truck driver on the Ho Chi Minh Trail and he was very proud of what he did – and there was a strange ambience between the pride of the family and this disaster that had struck them. Those two blind girls were the first ones I ever saw.”

Agent Orange was one of a series of colour-coded agents known as the Rainbow herbicides. They were first sprayed on crops as part of a “Food Denial Program” designed to force reluctant villagers into ‘strategic hamlets’. When this proved ineffective, defoliation was used in Operation Ranch Hand to deny enemy forces jungle and forest cover.

Spraying increased in intensity throughout the 1960s, to become what Yale University botany Professor, Arthur Galston called “the largest chemical warfare operation in history.” But even though Vietnam’s forests and hilltops were laid bare, spraying was widely recognised as both militarily and psychologically ineffective.

As the Americans continued spraying, indications of the toxicity of Agent Orange and its deadly contaminant of dioxin became evident. “I think the earliest indications that Agent Orange was harmful were when people came down with chloracne at some of the companies who were making it,” says Griffiths. By 1969, “…tests revealed that as little as two parts of dioxin per trillion in the bloodstream was sufficient to cause deaths and abnormal births in laboratory animals.”

A by-product of chlorine production, dioxin works as an “environmental hormone.” It causes disastrous changes at a hormonal and genetic level – causing diseases and deformities ranging from liver cancer and diabetes to spina bifida and leukaemia. Because these diseases also occur naturally, and because there is reluctance on the part of chemical companies and the US government to admit liability, there is no universally recognised link between dioxin and its associated diseases.

Griffiths began documenting the full horrors of the genetic effects of Agent Orange at Tu Du Hospital in Saigon. “I went in and it was this dark room filled with all these deformed foetuses.” Griffiths photographed conjoined twins, collapsed skulls and twisted spines, yet somehow he photographed these dead babies with a gentle tenderness. “I tried to give them some humanity,” he explains. “Some are hugging or embracing. I didn’t want to turn it into a freak show.”

As Griffiths continued to photograph, the full scale of Vietnam’s tragedy became apparent to him. In 1998 he visited Cam Nghia, a village where 10% of children were born with serious deformities. “Cam Nghia had the highest number of abnormalities in Vietnam, but what you’re not told is that in the majority of cases the foetus doesn’t even develop. And then there are miscarriages and live births dying within 48 hours.”

In 1971, the use of Agent Orange officially ceased in Vietnam, but its contaminant of dioxin is still claiming fresh victims today. “The toxicity is so great that once it is in your body, you can’t get rid of it. The exception of course is lactating mothers who can pass it out through their milk to their children. Now they’re finding concentrations of dioxin in the sediment of this fishpond where the levels are the highest they have recorded in the world, and yet the people are still eating the fish from there. Anywhere else in the world people would be moved out and the earth would be put into plastic bags taken away and buried”.

Griffiths believes Vietnam presents a unique, and missed, opportunity to study what happens to victims of dioxin. “You’ve got people who are culturally and ethnically identical living around Vietnam. Only the south was sprayed – the north wasn’t sprayed, so you’ve got your control group there and it gives a wonderful opportunity. But almost the only company that are doing major research are Hatfield Consultants of Canada who are doing a lot of good work.”

American veterans are still suffering from Agent Orange exposure, and are seeking compensation above and beyond the 1984 settlement of US $180 million (though no admission of liability) won from chemical companies that produced Agent Orange.

The Vietnamese have never received any compensation for the chemical warfare visited upon them. Instead they have an inheritance of death and deformity. Philip Jones Griffiths’ Agent Orange is a devastating record of these victims of chemical warfare.

A version of this review previously appeared in the Far Eastern Economic Review.