Next week, 160 governments - meeting in Geneva under the auspices of the Basel Convention, the United Nations treaty regulating trade in toxic waste - will address the growing crisis.

But phone users do have something to cheer about: a new gadget to combat the curse of the noisy mobile conversation. The Cooltalk VoiceBox, a device similar to those used by security agents, is said to filter out blaring music or rattling trains using microchip technology, so that the person on the other end hears only the speaker's voice.

Users trade up to a new handset on average every 18 months. As a result, some 105 million handsets are discarded in Europe each year, enough - if placed end to end - to stretch from London to a point 150 miles beyond Perth in Australia. Even more - 130 million - are thrown out annually in the United States.

Tests by both the US and the Californian environmental protection agencies have established that they should be classified as toxic waste. The cadmium in a single battery from an old phone could seriously contaminate 600,000 litres of water, enough to fill a third of an Olympic-sized swimming pool. Cadmium is being phased out of new batteries, but many other poisonous materials remain. Lead - which affects the immune, endocrine and central nervous systems, and causes serious damage to children's brains - is used to solder components to the printed wiring boards. Brominated flame retardants, used in wiring boards and plastic cases, have been associated with cancer, liver damage and problems with the neurological, immune and endocrine systems. Beryllium, which can cause serious lung damage, is used in contacts and springs and highly toxic dioxins can be emitted if the phones are incinerated in waste plants.

Experts add that many phones at the end of their lives are exported to developing countries such as India, Pakistan and China where they are broken up for recycling in rudimentary conditions, threatening workers' health and their communities. Colombia, Nigeria, Brazil, Botswana, Uganda, Namibia and Kenya all voiced alarm at the impact of discarded phones on their countries at a previous Basel Convention meeting.

The convention is now working closely with the United Nations Environment Programme (UNEP) and mobile phone manufacturers to tackle the crisis. It is working on designing new phones with safer components, collecting discarded phones, and recycling and disposing of them safely.

In Britain, over the past two years, a partnership between the Government, network operators and major retailers, called Fonebak, has collected and recycled more than 3.5 million phones - about one-10th of those discarded.

They are recycled in Bucharest, Romania. Nickel is recovered from batteries for use in saucepans, irons and new batteries. Small amounts of platinum, gold, silver and copper are recovered for jewellery and pipes. And the plastic is sent to Sweden where it is burnt to provide central heating for a village.

Klaus Toepfer, UNEP's executive director, says that the growing partnership with the industry should "serve as a model and an inspiration" for other businesses.

Critics hope that next week's meeting will impose legal controls on the trade in old phones. The Basel Action Network, a coalition of environmental groups, wants exports of all hazardous waste from rich countries to poor ones to be banned.