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Smartphones face a bit of a challenge when it comes to environmental sustainability, given their heavy reliance on such potentially toxic materials as lead, bromine, chlorine, mercury, and cadmium to form their circuitry and casings. That may lead one to believe that a sustainable smartphone may not be in the cards for consumers who want to make choices that are good for the environment.

But that's not true. In fact, it's actually pretty easy to cut your phone's environmental impact in half—simply by using it twice as long. And that will be good for your finances, as well.

Doing this is more appealing than it used to be, because smartphone innovation seems to have plateaued in recent years. Today’s smartphones, particularly many of the recommended models in our Ratings, are already quite good, especially when it comes to important characteristics such as camera quality. So the temptation to ditch your current phone for the newest model two years down the road shouldn’t be as strong as in the past.

The change in how we pay for our phones makes a difference, too. Today, most consumers pay off their phones in about two years, and then see their monthly bills drop by $20 or more—so the longer you keep your phone, the better for your wallet as well as the environment.

If you are interested in choosing a sustainable smartphone, that promises to keep you happily connected for a long time, consider the following seven features. And when you do decide to make a switch, you can do the responsible thing by properly recycling your old smartphone.

7 Features that Make for a Sustainable Smartphone

Carrier mobility. As our most recent cell-service survey by the Consumer Reports National Research Center shows, more people than ever are willing to switch cell providers, even the ones they’ve been with for a long time, to take advantage of better prices or service. Unfortunately, such moves often mean having to replace the phone you already have for one that’s compatible with a new provider's network. But a growing number of phones in our Ratings come with the radios and other hardware necessary for handling the voice and high-speed LTE data services of various cell providers, including the major ones: AT&T, Sprint, T-Mobile, and Verizon. Changing services is often as easy as swapping one nano-SIM card for another. And when you’re traveling abroad, you can avoid expensive network roaming charges by popping in a prepaid SIM card from a local carrier.

Dual SIM slots. This feature lets one smartphone handle two lines, which may reduce the burden on the environment—and your wallet—that would result from having to buy a second phone to meet the needs of a demanding personal and professional life. Most dual-SIM smartphones only support GSM-based networks, which means you can use it with providers such as AT&T and T-Mobile, but not Sprint or Verizon. Also, some models, such as the ZenFone 2, only allow the main SIM card (SIM1) to access a cellular data network for emails, the Web, and apps.

Expandable memory. Today’s high-resolution smartphone cameras capture life in a big way—and that goes for file size as well as drama. Those 5-megabyte snapshots and 1-gigabyte video clips you take with them can quickly scarf up the internal storage of most smartphones, which typically come with16GB to 32GB of storage. You can spend hundreds more on a smartphone with more internal storage, or take the cheap way out: Choose a smartphone that accepts microSD cards, which can be added easily and cost as little as $20 for 64GB.

Replaceable battery. It's just a matter of time—and the physics behind battery design—before the smartphone you love begins to nag you for a recharge way before it's practical to oblige it. For many smartphone owners, the fix to shortened battery life may mean an expensive warranty repair or even new phone. But if you buy a phone with a user-replaceable battery, you can swap in a new one for as little as $20 to $30. What’s more, you'll also have the enviable option of keeping a second battery on hand for long trips with limited charging opportunities.

Water resistance. Drowning is one of several smartphone accidents few, if any, smartphone manufacturer warranties cover. And insurance plans, with their high premiums and deductibles, are rarely worth it. But a drowned phone isn't a headache the owners of a Samsung Galaxy S7 are likely to face. In our tests, this aqua-comfortable smartphone survived immersion for up to 30 minutes in about 5 feet of water. Amazingly, it did so without a physical cover for the USB port.

Drop resistance. It’s not only water damage that can send your smartphone into the recycle bin. One fateful fumble onto hard pavement or ceramic tile can also shatter your dreams of a long and happy smartphone relationship. But phones such as the Moto Droid Turbo 2 seem quite able to handle such unplanned mishaps, thanks to what Motorola calls a five-layer ShatterShield display and other manufacturing techniques. It seems to work. Hopefully, more smartphones will follow in that model's footsteps.

Modular upgrades. LG, Google, and other big players in the mobile industry have been toying with the concept of designing smartphones whose components could be swapped out by their owners in order to substantially improve or change the functions of the phones already in their hands. The advantages of this approach over traditional, third-party solutions is that such modules would not only look like they’re a natural part of the phone but also function more smoothly because they would plug directly into the phone's core systems. The LG G5, one of the highest-scoring phones in our Ratings, is one such phone. But others will likely follow, including a rumored phone from Motorola (now owned by Lenovo). Stay tuned.

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