Pressures to learn English were a major reason why many children failed to learn the language of their ancestors and had led to a rise in the extinction rate of the world's estimated 6,000 tongues, linguists told the meeting.
Lyle Campbell, a linguistic researcher at Louisiana State University at Baton Rouge, said that of the 1,500 or so languages that existed in the New World at the time of European colonisation, the majority had already died out and only a handful would survive another generation.
'There are people who think English is a real virus and there is a kind of conspiracy out there to reduce the world to some McDonald's standard. That sort of spread of major world languages in English is likely to happen irrespective of what values we put on it. Some people may think it's a good thing,' he said.
But, he said, the scale of language loss had become very distressing and linguists had set up an international task force to try to arrest the decline.
Dr Campbell cited the case of California, which once had more native American languages than anywhere else. 'At the time of European contact there were roughly 200. There are about 100 left and of those 100 there are no children learning any of them,' he said. 'That means within our lifetimes probably 100 languages will die out in California.'
There were attempts to revitalise dying languages, he said. 'There are people trying to learn the language of their grandparents, or relearn languages that have already become extinct, but it's too early to know what success they will have.'
Donald Ringe, from the University of Pennsylvania, said pressure on ethnic minorities to learn English was enormous. 'It is partly the advantage you get if you learn English. If you want to be a traditional native American you'd better resign yourself to being poor.'