Growing concern over India's e-waste
The waste is mainly from Western Europe and North America
Thirty million computers are thrown out every year in the US alone, and many are dumped in India and China.
Some 70% of the heavy metals in landfills come from electrical equipment waste.
Now concerns are being raised on the impact the dumping - particularly evident in India's computer heartland, Delhi - is having on both the country's environment, and its people.
"The problem is that these computers, which are quite old, have a lot of toxic material in them," Ravi Agraval, leader of campaign group Toxic Links, told BBC World Service's One Planet programme.
"They have things like mercury, lead, flame retardants, and PVC-coated copper wire.
"When you try and extract or recondition these computers you release these heavy metals and these chemicals. These are disasters for the environment."
E-waste heads to India, China and Bangladesh because computer "recycling" is a good business, with much money to be made.
Computer recycling involves employing people to strip down the computers and extract parts that can be used again in machines to be sold on the high street.
"The process of extraction uses all kinds of chemicals, like acids - which then get dumped into the soil and go into the groundwater," Mr Agraval said.
"When you burn things like PVC-covered copper wire, you have emissions of very toxic chemicals like dioxins, which get released into the local environment."
There are also fears that the recycling process, an unregulated industry in India, is also very harmful to the health of those employed to do it.
In particular, the job involves exposure to a number of toxic chemicals both as part of the recycling process and within the computers themselves.
"The people actually doing the brunt of the recycling are people on less than half a dollar a day - women and children working in very shanty-like, disastrous, inhuman conditions," Mr Agraval said.
"For them, it's the difference between poison and a livelihood."
He added that a health survey had shown that recyclers regularly suffered from complaints such as respiratory diseases and skin rashes.
"It's difficult to say when you're in that state of poverty what really affects what, but certainly they are people on the edge, and any such exposure can't be doing them any good."
Such complaints have led to calls for regulation on the way computers are recycled, including workers potentially having to wear masks.
Mr Agraval emphasised that change needed to come from brands, which could instruct their suppliers to be more environmentally friendly.
The brands could also change some of the components in their own products, he said.
Some companies have already been offering to take back and recycle the computers themselves.
"Today, consumers are approaching us to take [the computer] in, but in the future with the new legislation, they will be able to dispose of it at the local municipality waste site," said Klaus Hieronymi, from Hewlett Packard's European Environmental Programme.
"The industry will have to organise that it is picked up there and put into the right recycling process."
He said that Hewlett Packard was also attempting to reduce the levels of cadmium and mercury in its products in preparation for the legislation, which comes into force on 1 January 2006.
Almost half of one range now did not contain a mercury lamp, he said.
Meanwhile in India, Mahinder Agowal, who represents the All Delhi Computer Traders Association, said that the risk to employees who recycled computers was relatively small.
"Out of the 2,000 shops most are in a good condition," he argued.
"Only some - very few - are in a bad condition. That happens in any market.
"If you go to a cigarette shop you wouldn't expect it to be in a good condition, so I feel most of the shops are fine."
However, one recycling shop visited by One Planet reporter Richard Hollingham - and credited by Mr Agowal's organisation - was clearly cramped with strong-smelling chemicals in the air.
Mr Agowal defended his organisation's members, arguing that many of them had set up business with very little money."Each will conduct business according to his own resources," he said. "We can't interfere with that."