Old computers don't just fade away -- and that's where the problem begins. Just ask IBM, which handled 60,000 tons of computer equipment at the end of its useful life in 1999, coming just from equipment it leased and its own internal operations. But that volume is nothing compared with the avalanche of old machines that could soon bury IBM and other computer makers if pending legislation in Europe and elsewhere requires them to take back their products. The EPA estimates that 75 percent of obsolete electronics are still gathering dust in storerooms and attics. The reason behind such warehousing of useless products is simple: No one agrees on the best way to dispose of them. "There's still not an infrastructure for recycling electronics as there is for newspapers," said Renee St. Denis, manager of product recycling solutions for Hewlett-Packard. It is, she said, "an industry that's still evolving." The major obstacle impeding progress of electronics recycling is the uniquely hazardous nature of the material. Those on all sides of the issue are focused on two primary concerns: the sheer number of devices involved and the environmental risks posed by certain components if they are improperly discarded. Of most concern are heavy metals such as lead, mercury and cadmium , as well as chlorofluorocarbons and brominated flame retardants, which can seep from landfills into water supplies or waft from incinerators into the atmosphere. "The immediate problem is a solid waste problem," said the US Public Interest Research Group's Jeremiah Baumann. "The more fundamental problem is the use of toxic metals, heavy metals, in computers." The potential for harm from many of those elements has been well established and has forced changes in consumer products. Lead, for instance, has been banned from petrol and household paints, and high mercury levels have kept certain fish off restaurant menus for years. The exact extent of the threat from those elements in PCs and related devices, however, has not yet been established. "What is known is that PCs will leach, can leach and do leach," said Ted Smith of the Silicon Valley Toxics Coalition, which estimates that 40 percent of the lead in landfills comes from consumer electronics. Smith acknowledged the need for more testing but said, "What is known is that if you burn this stuff, the metals don't burn and get back out into the environment." The European Union says the hazardous content of electrical and electronic equipment will cause "major environmental problems" if obsolete machines are not suitably treated -- and that lack of proper treatment is the norm, with more than 90 percent of electronic waste dumped in landfills, incinerated or recovered without proper precautions. Those companies that do follow careful cleanup procedures face yet another daunting challenge: the financial cost of doing things right. Last year, the Public Service Enterprise Group -- a partner of the EPA's WasteWise programme -- resold 128 computer systems and 150 monitors and donated just over 400 computer systems to community organisations such as the Boys and Girls Clubs, on top of several hundred that it sent off for recycling. The cost was $130,000 (£90,000), but the equipment that was sold raised only about $43,000 (£30,000). "This operation runs in the red," said Gary Wohler of the enterprise group. "Our impression is that the market for this stuff is somewhat limited -- it's becoming somewhat saturated now." HP has had costly experiences as well. The company runs its own recycling operation, which deals with some 1,500 to 1,700 tons of obsolete systems per month. The programme is run jointly with Canadian mining company Noranda, which sees an opportunity to mine for materials from PCs that it otherwise would dig out of the ground. The returns hardly constitute a moneymaking operation. "We pay Noranda to process this material," HP's St. Denis said. "It's definitely a cost business for us, but one that we feel is important to participate in." Not all companies have had such expensive experiences. Sony's Mark Small said his company's costs were just "pennies per pound" in a 1999 pilot recycling program with the state of Minnesota. Sony believes that in a five-year, national program it would be possible to "get recycling costs down to zero, or at least below landfill costs," he added. The manageable costs were particularly surprising because the project focused on the removal of residential products, in part because their relative lack of uniformity makes them more expensive to process. The program collected nearly 700 tons of used electronic products -- about ten percent of them PCs and monitors -- at a cost of just under $300 (£209) per ton. "One thing we learned in our project is that it actually costs a lot less than people thought," said Tony Hainault of Minnesota's Office of Environmental Assistance. Although Sony's experience appears to be the exception, he is hopeful that a solution for wide-scale recycling may not be far off. "The fundamentals of the infrastructure are all in place," Hainault said. "It's just a matter of will, to decide now is the time to do this." Click here to go return to the intro of our Recycling Special Report: Who pays for recycling hardware? Click here to go to Part III of our Recycling Special Report: A way forward. Click here to go to Part V of our recycling special report: Designing PCs for the environment. See ZDNet UK's NetBuyer guide to recycling PCs -- complete with details of useful organisations that can help. 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