Mountains of discarded remote controls litter the warehouse floor. In a dimly lit room, women on plastic stools pry open the devices, as if shucking oysters, to retrieve the circuitry inside.

In a narrow alley a few blocks over, a father and son from a distant province wash microchips in plastic buckets. Men haul old telephones and computer keyboards off a truck.

Some items will be refurbished and resold, others will be stripped for components or materials such as copper or gold.

Business is booming in Guiyu, where the world's electronic waste ends up for recycling, and is set to get even better.

However, the industry has a heavy environmental cost. Electronic remnants are strewn in a nearby stream, and the air is acrid from the burning of plastic, chemicals and circuit boards.

Heavy-metal contamination has turned the air and water toxic, and children have high levels of lead in their blood, according to an August study by researchers at Shantou University Medical College.

Much of the e-waste that has passed through Guiyu over the past few decades came from outside China.

Western countries are now making greater efforts to process their own e-waste, but Chinese domestic supply will soon be more than enough to step into any breach, campaigners say.

"Before, the waste was shipped into China from other parts of the world - that used to be the biggest source and the biggest problem," Ma Jun, director of the Institute of Public and Environmental Affairs, one of China's foremost environmental NGOs, said.

"But now, China has become a consuming power of its own," he said. "We have, I think, 1.1 billion cellphones used, and the life of our gadgets has become shorter and shorter."

"I think the wave is coming," he added. "It's going to be a bigger problem."

China currently generates 6.1 million metric tons of e-waste a year, compared with 7.2 million for the US and 48.8 million globally, according to the United Nations University's Solving the E-waste Problem Initiative.

But while US e-waste production has increased by 13 percent during the past five years, China's has nearly doubled, setting the Asian giant on track to overtake the US as the world's biggest source as early as 2017.

Nowhere are the profit and environmental toll of e-waste recycling more noticeable than in Guiyu, where about 80,000 of 130,000 residents work in the loosely regulated industry, according to a 2012 local government estimate.

More than 1.6 million tons of e-waste pass through Guiyu each year, with recycling worth 3.7 billion yuan ($605 million) annually, attracting migrants from near and far.

"This work is tiring, but the salary is OK compared with the work in town," said a 30-year-old surnamed Ma, who left a salesman's job to dismantle electronics. "You can make 4,000 or 5,000 yuan a month."

At the same time, the town has made worldwide headlines for the devastating health impact of its tainted environment.

"People think this cannot be allowed to go on," said Leo Chen, 28, a financial worker who grew up in Guiyu.

The situation is better than it was a decade ago after official interventions, but the effects of years of pollution remain.