Sey is an 8-year-old Phnom Penh glue-sniffer. He lives with a group of mud-caked friends in a squalid encampment beneath the Monivong Bridge.

A visit finds the carefree band of brothers perched on a pile of old tires. Ten or so youths sprawl in postures of practiced nonchalance - some smoke cigarettes, others wager over a heated card game. They frequently fight, both playfully and fiercely, over whose turn it is to inhale mind-numbing chemicals from a plastic bag filled with glue.

When the bag reaches Sey, he wraps it expertly around his fingers. The inside is coated with yellow glue, the tube of which he gleefully produces from his pocket. Every few minutes, Sey's delightful smile vanishes momentarily as he inhales the fumes. His discolored skin is spattered with scars, blisters and cuts. Only in the depths of his bloodshot eyes is his youth betrayed - they occasionally glimmer with the childish curiosity that should be a hallmark of his tender years.

In a bounding pack, the boys roam the river bank. Their bony knees protrude from shorts stiff with dirt; the skin on their torsos is stretched taut over rib cages and shoulder blades. With quick, restless movements their blackened fingernails scratch at the tufts of matted hair that crown their dizzy heads.

A riverside life of camaraderie and glue-induced escape is a more enticing option than either a family home or an NGO-run shelter. Professor Ka Sunbaunat of the University of Health Sciences says forming a unit with other children is a legitimate response to a lack of other support in these children's lives.

"When the children joined together they all had the same problems and the same purpose," he said. "They were aiming to create their own society, to share and understand and help one another. They were all looking for help. When they joined together they tried to create the support they craved."

Huffing, or inhaling, has become an increasingly popular means of ingesting glue to get high, says David Harding, technical adviser for Friends International, but in addition to the severe mental and physical consequences of inhaling volatile chemicals, the process of inhalation has other dangers.

"With glue sniffing, the method of ingestion - sharing plastic bags - makes users more vulnerable to the transmission of infections such as TB," he said. Moreover, users risk chemical burns on the face that can get quite severely infected.

Sey's friend Darti, 13, roams the riverfront in a tattered blue waistcoat. He spends the day begging, shining shoes and catching sparrows. In the evenings, he plays cards or goes scavenging through the city streets.

"Sometimes I eat; sometimes I don't," he said. "I wake up at eleven o'clock - it is late because I go to bed late, maybe at one or two in the morning."

Other riverbank kids told Darti that sniffing glue was chnang - delicious - and encouraged him to try. When he was 11, he did, and now agrees with his friends.

"When I take glue I go to Tansour - a good place, a happy place," he said. "If I don't have money to buy glue I get a fever but feel cold and my head hurts."

The large welt on his foot is the result of a scrape with police. Punctuating each word with a sideways glance, he explains that the police hit him with wire cables if they see him on the streets. He hides if he learns they are likely to be patrolling.

Sunbaunat said difficult family environments can force children to depend more on their peers and leave them vulnerable to drugs.

"All of them have very difficult family backgrounds," he said. "They are often orphans or have lost a parent, or do not have their parents' active presence in their lives."

Chewing distractedly on a blade of grass, Darti fends off playful attacks from younger friends.

"My mother died when I was 11," he said. "She died because my father got very drunk and hit her too much. My father died of drinking too much. When my mother died I felt very sad and cried a lot."

Darti says he's content living on the riverbank with Sey and his other friends. In the evenings, they take the food left as offerings on shrines and eat it on the river's edge.

But Darti has a secret dream: "I like living on the streets with all my friends, but I would really like to be a pilot. I want to fly an airplane."