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.

"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."

But activists say far too much of the nation's electronic garbage _ not only PCs but also TVs, radios, batteries and other materials _ still 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, e-waste 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 and businesses each day.

Only 10 to 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.

Among the e-waste that is recycled, activists say, up to 80 percent is exported overseas to dismantling shops where poor workers are exposed to hazardous fumes and chemicals while trying to extract valuable metals and components.

Researchers for Greenpeace International have detected high levels of toxic metals in soil and water samples collected around electronics-dismantling workshops in China and India.

A growing number of countries and states are requiring electronics companies to take responsibility for recycling their products.

Japan, South Korea and most European countries now require electronics manufacturers to pay for and manage recycling programs for their products.

There is no such federal law in the United States, but Washington, Maine and Maryland recently passed "take-back" laws and about a dozen other states are considering such legislation.

California made it illegal to throw away nearly all electronic products last year, but the state doesn't require manufacturers to take back their products. Instead, when consumers buy electronics, they pay fees to cover the cost of recycling those products later.

E-waste advocates are pushing "producer responsibility" because it gives companies an incentive to make their devices more environmentally friendly.

"It's essential that manufacturers think through the end of life of their products," said Rick Hind, legislative director for Greenpeace's toxics campaign. "No matter how they recycle, it doesn't matter if there are still toxic materials in their computers."

Among computer manufacturers, Dell has emerged as a leader in electronics recycling. The Round Rock, Texas-based company has pledged to phase out certain toxic chemicals and began offering free recycling for all its products in December.

Chairman and CEO Michael Dell challenged the industry to follow his company's lead in his keynote address at this year's Consumer Electronics Show in Las Vegas, saying, "It's the right thing to do for our customers. It's the right thing to do for our earth."

The company recovered 80 million pounds of equipment in 2005. Some computers are refurbished and resold _ possibly overseas _ while parts or materials are recycled within the U.S. if equipment can't be fixed, said Dell spokesman Bryant Hilton.

"Our goal is to make it as easy to recycle a computer as it is to buy one," said Hilton, adding that the company's electronic waste isn't shipped overseas.

Hewlett-Packard recycled 164 million pounds of hardware and print cartridges globally last year, 16 percent more than the previous year. In the U.S., the company recycles about 50 million pounds at its plants in Roseville and Nashville, Tenn. and doesn't send any of that waste stream to landfills or overseas.

Since it began recycling 20 years ago, Palo Alto-based HP has set out to design products that last longer and are easy to recycle, said John Frey, who manages the company's environmental strategies.

HP still charges for recycling, but consumers get a coupon that goes toward the purchase of new products. It also organizes collection drives at retail stores where consumers can drop off old gear for free.

"Being environmentally responsible makes sense for our business _ it affects brand loyalty and how customers view us," Frey said.

But the problem is far wider than just computers.

Activists are focusing more attention on televisions, which make up an increasingly large share of the world's electronic waste. As more Americans switch to flat-panel TVs, they are throwing out clunky cathode-ray tube sets that contain large amounts of lead.

"The TV industry needs to step up and create some takeback programs," Kyle said. "Ultimately, they must design their stuff in a way that makes them easier to recycle."