Inside Hewlett-Packard Co.'s cavernous recycling plant in the Sacramento suburbs, truckloads of obsolete PCs, servers, and printers collected from consumers and businesses nationwide are cracked open by goggled workers who pull out batteries, circuit boards, and other potentially hazardous components.

The electronic carcasses are fed into a massive machine that noisily shreds them into tiny pieces and mechanically sorts the fragments into piles of steel, aluminum, plastic, and precious metals. Those scraps are sent to smelting plants, mostly in the Sacramento area, where they are melted down for reuse.

The computer industry is ramping up its campaign against electronic waste, a dangerous byproduct of technology's relentless expansion.

HP and Dell Inc., which together sell more than half the country's PCs, are earning praise from environmentalists for using more eco-friendly components and recycling their products when consumers discard them. But every major computer manufacturer now has some sort of computer recovery and recycling program available for its customers.

"The computer companies are definitely embracing the idea that they need to deal with their products at the end of their useful life," said Barbara Kyle, who coordinates the San Francisco-based nonprofit Computer TakeBack Campaign. "There's been a complete turnaround."

Still, activists say far too much of the nation's electronic garbage--not only PCs but also TVs, radios, batteries, and other materials--ends up in landfills or gets shipped overseas to poor countries, where it pollutes the environment and exposes workers to dangerous chemicals.

"The United States is not responsibly managing this waste stream," said Sarah Westervelt of the Basel Action Network, a Seattle-based group that seeks to stop the spread of hazardous waste. "We're allowing it to go offshore and poison developing countries."

The push to recycle reflects a broader greening of the tech industry.

In addition to recycling and eliminating toxic chemicals, more companies are making their products energy efficient, using eco-friendly packaging and offsetting their carbon emissions to curb global warming.

"This focus is good for business," said Carl Claunch, a computer industry analyst at the technology research company Gartner Inc. "There's a growing pool of customers who value environmentally friendly products."

Still, eWaste is a growing environmental and public health concern as the world becomes more wired and companies introduce new products at a faster pace.

Discarded computers, televisions, radios, batteries, cell phones, cameras, and other gadgets contain a stew of toxic metals and chemicals such as lead, mercury, cadmium, chromium, brominated flame retardants, and polychlorinated biphenyls, or PCBs.

The U.S. Environmental Protection Agency says American consumers generated nearly 2 million tons of electronic waste in 2005. Gartner estimates that 133,000 PCs are discarded by U.S. homes, schools, and businesses each day. Yet only between 10 and 15 percent of electronics are currently recycled, industry analysts say. The rest collects dust in people's homes or gets dumped into municipal landfills, where environmentalists worry toxic chemicals can leak out.