Beijing (AsiaNews/SCMP) – Lian Jiao, a township on the outskirts of Guangzhou metropolis (Canton) is the world's rubbish dump. Waste is carted here for recycling from the United States, Europe and many other nations.

Every day, tons of discarded supermarket food and products from the rich world end up in the city. Here, workers – often husbands and wives helped by their little children – pick through piles of rubbish by hand. Plastic wrappers are jet-hosed and doused in chemicals in nearby factory workshops, sending streams of dye and colourings directly into a heavily polluted river that flows into the Pearl River. Waste that is not fit for recycling - about 20% - is burned either in nearby incinerators or in workshop yards, sending plumes of black smoke into the air.

More than 30,000 migrant workers coming from China's poorest provinces work here, but after two or three years, many are forced to return home sick with fever, coughs, and skin blemishes. Some develop cancer or lung disease

Li Lengen, a migrant from Henan province, has worked in the rubbish heaps for two years with his wife and daughter. He said: "No one knows the reason why people get sick and there is no way to appeal for compensation or help [to pay medical expenses]. The pollution kills you slowly and secretly."

His 18-month-old daughter was born here, where "the river is black. The air is full of dust. When you breathe, your lungs fill with poison. I am worried my baby girl will not be strong enough to survive here but we have no choice but to stay - there is no work for us back home."

Migrant workers earn up to 800 yuan [eight euros] a month preparing plastic for recycling - four times what they earn for farm work. Many bring young children who help search among the rubbish dumps after school. Around 2,000 small companies pay 3,000 yuan for a ton of plastic rubbish; then they wash and chop it up to sell by the bag to plastics factories at a profit of around 500 yuan.

Huang Yintian, 45, from Sichuan province, said: "I work 14 to 15 hours a day, 30 days a month. The work is hard, dirty and dangerous. There is no time for rest.

"I work here because I am old, and I have no education and I have a wife and child back home to support. I haven't been home for two years because I can't afford to travel to see them. This is all I can do," he said.

Looking down at the foul tributary that runs through the town, migrant worker Yang Yichun, 50, says: "This has to be the dirtiest stretch of river in the world. One day it is black, the next day blue, the next day yellow, the next day red, all because the workshops wash the dye from the plastic straight into it.

From the wealthy West, the rubbish is shipped to Hong Kong and brought here. Recycled material is taken Guangdong's plastics factories. In western countries, people believe they are protecting the environment by separating waste. Every day, hundreds of tons of waste that do not end up in the river or burned, are buried in landfills.

Greenpeace said recycling activities contribute to severe air and water pollution in Guangdong. In the region, 55% of rain is acid rain and 20% of its rivers are heavily polluted.

Edward Chan Yue-fai, Guangzhou-based Greenpeace campaigner, urged the West to check where its waste was going and how it was being dealt with. "People may separate their waste with the best of intentions and have no idea what happens to it after it leaves their home, but a lot of the environmental problems we have in Guangdong province are due to the imported waste."