You're talking and talking and texting on your cell phone -- but you don't realize you could be harming the Earth as well, do you?

We don't give much thought to the environmental footprint of our handsets. It turns out that even our ubiquitous mobiles can be very harmful to the environment.

Toxic chemicals are released into the air and water when phone components are manufactured and assembled. Heavy metals leach into the soil of landfills when the phones are thrown out. Wars are fought in Africa to control the mines supplying essential elements.

But there's an alternative — companies such as Nokia, Samsung, and Motorola make "green" phones that use materials such as bamboo, recyclable plastic water bottles and corn.

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One type of green material isn't better than another, as long as it's recyclable, says Casey Harrell, coordinator of the electronics campaign for environmental group Greenpeace.

According to Harrell, when phone components such as circuit boards and electronic cables are built and assembled, the elements bromine and chlorine can be released into the environment, posing a hazard to residents living in surrounding areas.

Some bromated flame retardants (BFRs) don't break down in the air and can cause abnormal brain development in animals and people.

Even worse are the fumes from the mercury and lead that manufacturers work with. Phthalates used to soften the PVC, or vinyl, that constitutes most handset bodies permeate the air during both manufacturing and disposal and can be carcinogenic. Rare earth metals must be mined in remote locations to make electronic components.

According to the United Nations, 20 to 50 million tons of electronic waste, or e-waste, accumulate annually worldwide, and Harrell says that much of it is shipped internationally.

"In its total weight, [e-waste] is by far the largest amount of hazardous waste," he says.

To cut down on the toxic effects, Greenpeace pushes electronics manufacturers to produce green products and grades the results. Harrell wrote the January report "Toxic Tech: Switching On to Green Electronics," which includes a survey of cell phones.

The less PVC and BFRs a phone contains, the higher its "green" grade. For example, Samsung's F268 mobile phone is made of bioplastic and is both PVC-free and BFR-free. It scored a 4.5 out of 10, tops among the cell phones mentioned in the report.

Harrell also had kind words for the Motorola Moto W233 Renew as an example of how an electronics company can change its approach to manufacturing. The Renew is made out of recyclable plastic bottles and will be available in the first quarter of 2009.

According to Bill Olson, director of Motorola's Office of Sustainability and Stewardship for mobile devices, the Renew uses 20 percent less energy than phones made of ordinary plastic. The company also says the Renew requires less charging than other models and has a talk time of 9 hours.

"Not only is the W233 Renew an environmentally responsible phone, it delivers the high quality that is expected from a Motorola device at a price consumers can afford," says Olson.

Through an alliance with Carbonfund.org, Motorola has also made the Renew the first carbon-free phone, says Olson.

At the recent Mobile World Congress in Barcelona, Spain, Samsung introduced a solar-powered touch-screen phone: the Blue Earth, also made from recyclable water bottles. But it won't be available in the United States.

"Samsung's 'The Blue Earth Dream' demonstrates our small but meaningful commitments for the future and our environment," said Samsung vice president J.K. Shin in a statement.

The phone's talk time is unlimited as long as there's enough sunlight, according to Samsung.

Meanwhile, Nokia has a concept phone called Remade, which is made from recycled aluminum cans, plastic water bottles and rubber key mats in the aim of reducing landfill input.

Another Nokia model, the 3110 Evolve, has an unpainted biocover made from 50 percent renewable material.

"The Evolve was partly about a proof point — can we produce a viable device that has a plastic shell on it that is not made with petroleum materials?" says David Conrad, Nokia's North American senior manager for environmental affairs.

According to Conrad, the challenge is to educate the 1 billion people using Nokia devices to make green choices in the devices they purchase.

So what happens if you don't choose a green phone? Will you be harming the environment?

Although it's not illegal to throw cell phones into the trash, it's preferable to take your old phone back to the store where you bought it.

AT&T has a program called Cell Phones for Soldiers, in which recyclable phones go toward calling cards for soldiers in Afghanistan, Iraq and other locations.

"Buy electronics from companies that will take their electronics back, so they don't end up in a dumpster in this country or overseas," says Greenpeace's Harrell.

Even better is to choose a green cell phone. That way, you send a signal to phone makers to extend their green efforts beyond just a product or two.

"Any time consumers want to make a difference, voting with their wallet is a key way to send that signal," says Harrell.

Harrell wants to see across-the-board replacements rather than just a narrow niche of green handsets.

"What are you guys doing with the rest of your phone line?" he asks about all phone makers. "There shouldn't be greener and less green. They should all be green."