A Bangladeshi student I saw recently attempted suicide after failing to pay his tuition fees. On closer questioning it turned out his parents had sold off almost all their land and taken out a sizeable loan from a moneylender at an extortionate rate. They were banking their future upon him completing his degree in Australia and gaining permanent residency.

As if to underline the depths of his despair, he showed me a picture of him dressed up as Santa Claus to advertise a suburban car wash business. It was one of his three part-time jobs.

His situation is hardly out of the ordinary. While there are overseas students from wealthy families and developed countries, the bulk are from households of moderate means, usually from Asia.

As someone born in Bangladesh, but raised in Australia, I often feel like an unelected representative of the Third World. I watch new migrants arrive in Australia or observe them on my trips to visit family and wonder how life would have been different if my parents never migrated here.

But now I have a fairly good idea. I would be one of the hundreds of thousands of young people like that Bangladeshi student. While the letters PR may mean spin and media manipulation to many of us, to them they stand for permanent residency, the holy grail, the key to prosperity and security for their family. It is their ticket to a better shot in the great game of globalisation.

International students bring in close to $11.3 billion a year in revenue, making it Australia's fourth largest export industry. It represents one of our key trade relationships with the emerging powerhouses India and China.

As government funding has declined, universities are increasingly dependent upon international students to survive. In lecture theatres across Australia, they are thick on the ground.

There has also been much controversy about whether this dependency has led to a decline in university standards, as they try desperately to placate and to pass their burgeoning ranks of overseas clientele.

Some universities have been the target of allegations that their degrees are little more than extended migration schemes, with the qualifications useful for only the points on the residency application but almost worthless in the employment marketplace.

But what is less commented upon is that overseas students are fast becoming one of the most vulnerable groups in our society. Working in mental health, I see more and more each month and their situations are often horrendous. Suicide attempts, self harm or drug overdoses are the most common way they present, usually in relation to financial and study pressures. It is complicated further by language and cultural difficulties and lack of adequate health insurance.

A 2004 study by the University of Queensland found their international students were three times more likely to suffer depression than local students through the course of their study.

Only this month a house fire in suburban Melbourne killed three Indian students. It emerged that they were sharing the one room in bunk beds and would sleep in shifts while the others were working part time jobs. Overcrowding and difficult living conditions may have contributed to the accident.

Overseas students are the new refugees, living on the edges of Australian society under the weight of visa difficulties, imminent deportation and reduced access to social services. They inhabit that ill defined landscape of unbelonging.

They increasingly staff the lower end of the labour market. In fact, within the hierarchy of the working poor, they are kings and queens. Ask any petrol station attendant, a car wash worker or taxi driver and there is a good chance that they are an international student.

Despite their plight, most of them would not have it any other way. The alternative of trying to eke out a living in their homelands is much worse. Government surveys in 2005 found that about 80 per cent of international students were satisfied with their experience.

While we celebrate the end of local class conflict and suggest there is a diminishing working class, international students are a reminder that the rank and file of the world economy has shifted. This is particularly clear when they present to the hospital, a space where the south meets the north. The staff consist primarily of overseas doctors from the subcontinent, nurses from the Philippines and Zimbabwe and cleaners from the Middle East. It is the flip side of outsourcing, an "in" sourcing of cheap labour to fill skill shortages.

When I see patients like the Bangladeshi student, there is an underlying tension infusing the consultation. His eyes suggest a mix of desperation, longing and envy. While he looks like me and has a name like mine, I inhabit a completely different stratum. It is as if there is an invisible border representing unfettered access to the developed world that is just out of his reach. For me, there was the difficult decision by my parents decades ago to board a plane and start a new life in an unknown land. And that made all the difference.