Lying on her bed that night, staring at the bunk above her, the slight 19-year-old complained she felt worn out, her roommates recalled. She was massaging her aching legs, and coughing, and she told them she was hungry. The factory food was so bad, she said, she felt as if she had not eaten at all.

"I want to quit," one of her roommates, Huang Jiaqun, remembered her saying. "I want to go home."

Finally, the lights went out. Her roommates had already fallen asleep when Li started coughing up blood. They found her in the bathroom a few hours later, curled up on the floor, moaning softly in the dark, bleeding from her nose and mouth. Someone called an ambulance, but she died before it arrived.

The exact cause of Li's death remains unknown. But what happened to her last November in this industrial town in southeastern Guangdong province is described by family, friends and co-workers as an example of what China's more daring newspapers call guolaosi. The phrase means "over-work death," and usually applies to young workers who suddenly collapse and die after working exceedsingly long hours, day after day.

There has been little research on what causes these deaths, or how often they occur. Local journalists say many of them are never documented but estimate that dozens die under such circumstances every year in the Pearl River Delta area alone, the booming manufacturing region north of Hong Kong.

The stories of these deaths highlight labor conditions that are the norm for a new generation of workers in China, tens of millions of migrants who have flocked from the country's impoverished countryside to its prospering coast.