Cancer legacy of Vietnam war

Millions of Vietnamese may have been exposed to poisonous chemicals like Agent Orange during the Vietnam War, a study suggests.

Researchers in the United States have found evidence to suggest that much more cancer-causing chemicals were used during the conflict than was previously thought.

The chemicals or herbicides were used to defoliate forests around military bases and to destroy enemy crops.

But they have also been linked to cancer, spontaneous abortions, miscarriages, birth defects and brain disorders in people.

The US military stopped using Agent Orange in 1971 after it was found to contain the most dangerous form of dioxin, TCDD, which causes cancer in rats.

Poisoning people

But experts say the chemical is still in the environment in Vietnam and continues to poison people living there.

A recent study of residents in Binh-Hoa, near Ho Chi Minh City, found some had 200 times the background amount of dioxin in their bloodstreams.

There are still about 12 dioxin hotspots in Vietnam, in areas where very heavy spraying took place.

This latest study, published in the journal Nature, suggests the US military used up to seven million more litres of cancer-causing chemicals than was previously thought.

Researchers at Columbia University in New York analysed US military records from the war.

Incomplete records

They found many records were incomplete. Their analysis suggested the US sprayed about 1.9m litres of the cancer-causing chemical Agent Purple during the conflict.

But military records suggested only 548,100 litres were ever purchased.

This type of herbicide was used between 1962 and 1965 and is believed to have had particularly high levels of dioxins.

Similarly, they found evidence to suggest that while some missions recorded spraying Agent Orange, they did in fact use the much more poisonous Agent Pink.

The different herbicides were nicknamed by the coloured identification band painted on their 208-litre storage barrel. They had varying levels of cancer-causing chemicals.

"Large numbers of Vietnamese civilians appear to have been directly exposed to herbicidal agents "

Nature

The researchers concluded the incomplete records meant the US military probably sprayed millions more litres of poisonous chemicals in Vietnam than previously thought.

Writing in the journal Nature, they said: "Large numbers of Vietnamese civilians appear to have been directly exposed to herbicidal agents."