A survey of 15,000 people aged between 15 and 19 found they were increasingly worried about financial security and their job prospects.

Mission Australia's 11th annual National Youth Survey also found that young people are becoming less concerned about the environment.

The environment was the top issue of national concerns in the past two surveys but has slipped to sixth place this year, with only 17.5 per cent of respondents saying it was the most important issue facing the country, compared with 37.4 per cent who made the same comment last year.

Mission Australia's national manager of research, Dr Bronwen Dalton, said the environment had been usurped by more immediate worries.

''The environment has been crowded out by this really dominant concern about the economy,'' she said.

Many young people said they would have to find work to support their families or expressed anxiety about their parents losing their jobs.

Dr Dalton said the young people surveyed were keenly aware of the global economic downturn and how it was affecting them.

''What stood out to us was these heart-wrenching comments about how they have got to get a job to support their families or mum and dad are out of work and they need to do more to keep the family afloat,'' she said.

''It was very troubling to see that young people were so concerned with financial security.''

Dr Dalton said the decrease in young people worried about the environment would be of concern to green groups but added that they were not disengaged from the issue, with more than one-quarter participating in environmental activities.