Measures to reduce the millions of tons of electronic waste generated each year by the manufacture of computers, mobile phones and other consumer electronic products are the focus of a United Nations-sponsored conference in Nairobi, Kenya.

Delegates from about 120 governments gathered in Nairobi on Monday to begin week-long talks on how to reduce the use of toxic substances, such as lead, cadmium and mercury found in PCs and mobile phones, and to promote schemes for recycling and re-using as many components as possible.

The UN estimates that up to 50 million metric tons of 'e-waste' are generated worldwide every year, representing more than 5 per cent of all municipal solid waste. In the US alone, as many as 20 million PCs are thrown out every year.

A good chunk of that waste ends up in Africa and other developing countries, according to the UN.

Every month, more than 100,000 discarded computers are entering the Nigerian port of Lagos alone, said UN under-secretary general Achim Steiner in a speech.

Local experts estimate that up to 75 per cent of the used PCs, TVs and phones sent from developed countries are unusable and end up in the landfills of developing countries, where the items are often burned, releasing toxic fumes and chemicals.

On the table at this week's meeting are proposals to encourage manufacturers to take more responsibility for their products, from the design stage through the supply chain to final disposal.

In a speech, Sachiko Kuwabara-Yamamoto, executive secretary of the Basel Convention, which monitors hazardous waste, pointed to a partnership with several mobile phone manufacturers and operators, including Nokia, Sony Ericsson and Vodafone to develop schemes for recycling and re-using the millions of mobile phones now sold worldwide every year.