Piles of computer waste are found in Guiyu
The transfer of hazardous waste is restricted by a 1989 treaty known as the Basel Convention, but the United States has not ratified it.
"I've seen a lot of dirty operations in Third World countries, but what was shocking was seeing all this post-consumer waste," said one of the report's authors, Jim Puckett of the Seattle-based Basel Action Network.
By publishing their report, the campaigners hope it will increase the pressure on American companies and politicians to do more to recycle computer waste.
Burning plastics
The report says electronic waste is the most rapidly growing waste problem in the world, with toxic ingredients such as the lead, mercury or cadmium being released into the environment.
The campaigners visited the waste sites in Guiyu, China, in December where people were smashing up machines to scavenge for the precious metals inside.
The report says that workers, with little or no protection against hazardous materials, burned plastics and circuit boards or poured acid on electronic parts to extract silver and gold.
The effect was to fill the air with carcinogenic smoke and pollute the water, said the report.
The campaigners said preliminary investigations in both Pakistan and India had revealed that these countries were also receiving and processing waste electronics from the West.
Problem 'ignored'
The growing amount of computer waste is becoming an increasing problem, with millions of devices becoming obsolete each year as the technology industry produces faster, better and less expensive equipment.
While there are recycling programmes in the US, campaigners say much of the waste electronics finds it way to the developing world.
The report suggested that as much as 80% of the America's electronic waste collected to be recycled is shipped out of the country.
"Everybody knows this is going on, but they are just embarrassed and don't really know what to do about it," said Ted Smith, head of the Silicon Valley Toxics Coalition, which also helped prepare the new report.
"They would just prefer to ignore it."