When I was covering the war in Viet Nam there were reports from Ha Noi in 1967 claiming that millions of people had been victims of chemical warfare. Officials in Saigon dismissed these as crude propaganda and for us journalists in the South there was little opportunity to verify claims made by the North.

In the summer of 1969 four Saigon newspapers ran stories with pictures of deformed babies born to women who had been sprayed with Agent Orange. The South Vietnamese government argued that the deformities were caused by venereal diseases and President Thieu closed down the papers for "interfering with the war effort." After such moves, tracking down any victims proved difficult.

In 1970 I heard stories that babies were being born without eyes. Remembering my time working in hospitals, as a pharmacist, in London, rumour had it then that the staff induced acidosis in a baby born seriously deformed (killing the child) to protect the mother from the trauma of seeing her baby. I assumed something similar could happen in the hospitals and orphanages of Viet Nam, except I reckoned, in those run by Catholics.

Over the next few months I visited as many such places as I could find. In almost all cases I was denied access, usually by polite smiling nuns. At the risk of sounding paranoid I became convinced they had been told to keep the press away.

By 1971, the word was out that the U.S. spraying had been officially stopped because of its harmful side effects. There was a flurry of news stories, but no pictures. I left Vietnam in the summer of 1971 without ever seeing a victim.

After the war was over I got back to Viet Nam and saw my first affected child. The initial situation was a mother with two blind daughters, born with no retinas. Later I saw children with empty eye sockets and still others with no trace of eyes at all.

Agent Orange contains Dioxin. Dioxin acts like a hormone. It gets to the receptors in the cells of a developing foetus before the normal hormones and directs the cells to do crazy things. The end result has been tens of thousands of deformed children and an even greater number of miscarriages and stillbirths.

Spending time with the affected children is never easy -- twenty year-olds living in ten year-old bodies. Some howling like animals, some giggling hysterically while others search with catatonic stares for meaning in the heavens. For the parents, their lives are never the same again. Giving birth becomes a game of roulette. I remember one day, with Bill Dowell of Time Magazine, meeting a Vietnamese mother who told us, "I was so terrified by what I had seen happening around me, that the moment my child was born the first thing I asked was whether she had both arms and legs." Many of the earlier pictures were taken while on assignment for Geo Magazine in the early 80's when Kodachrome 64 ruled the day. This meant lugging heavy 200w/s flash units around dimly lit locations to bounce light off less-than-white ceilings. Later, Kodachrome 200 and fast Zeiss lenses made working easier and in the last few years, as the project became self-assigned, I stuck with black and white film. For the book I converted the earlier colour to monochrome on the Imacon scanner. My initial motivation for spending 22 years engrossed in this subject has to do with witnessing a staggering human tragedy unfold. In many ways the sad and terrible Viet Nam war has become a war without end. The parents of the afflicted are an inspirational group showering love and care on their children. Most are desperately poor and any compensation offered by America would make a huge difference to their lives. The US did not drop Agent Orange to produce deformed babies - it was simply meant to kill vegetation. The Dioxin was an accidental by-product. This gives America a perfect excuse to be magnanimous towards the victims.

The other reason for my obsession is that we need to get to know more facts about Dioxin. Each and every person on the planet now has this deadly chemical in their bodies, mostly from industrial pollution and the embrace of plastics by society. Even the EPA declares that a quarter of all cancers in America are caused by Dioxin. Researchers on the subject cannot continue to ignore Viet Nam. It presents the perfect setting to determine the facts - one people, half in the South that were sprayed and those in the North who were not, thus providing a genuine control group. Getting a book like this in print was not easy and I was indeed lucky to find a brave publisher. It will not be an easy "sell" but in a perfect world it would be in every school library in the country. Readers who flock to the latest Tarrantino offering undeterred are, unfortunately, suddenly squeamish when confronted with reality. But as Gloria Emerson put it, "to turn way and not see the photographs is to compound the crime."