Vietnam's Red Cross has appealed for urgent help for victims of Agent Orange - the poisonous chemical dioxin used during the Vietnam War.
People affected by Agent Orange need help now and cannot wait years for more research, said the head of Vietnam's Red Cross, Professor Nguyen Trong Nhan.
He was speaking at the close of a scientific conference in Hanoi at which it was decided to set up a joint US-Vietnamese research committee.
The committee will look into new areas of research - such as the nature and causes of birth defects in Vietnam, and ways to reduce exposure to dioxin in the environment.
The US says more research is needed
Experts say dioxin is continuing to contaminate people 30 years after the US stopped spraying it over forests in south and central Vietnam.
But the BBC's Clare Arthurs says the US is reluctant to acknowledge any link between dioxin and people born with disabilities.
Cancer in rats
Rather than carrying out expensive tests to determine dioxin contamination, Professor Nhan said priority should be given to taking immediate steps to help victims.
"Anyone with a modest knowledge of science would know that these sort of toxic substances harm the human body and the environment," he said.
Agent Orange was used to destroy jungle cover
He said many Vietnamese had "died in bitterness" without compensation.
"So we can't keep silence any longer or wait for scientific evidence before making compensation," he said.
US forces sprayed millions of gallons of Agent Orange on Vietnam during the war that ended in 1975, to deny communist soldiers jungle cover.
The US stopped spraying in 1971 after it was discovered that it contained the most dangerous form of dioxin, TCDD, and caused cancer in rats.
Studies have shown that dangerous concentrations remain in some parts of Vietnam.
The four-day conference which ended in Hanoi on Wednesday helped establish the facts, said Professor Nhan
"The more evidence, the clearer and more undeniable the responsibility," he said.