It wasn’t always so, the second generation iPhone was far worse than other phones. The report says:

The iPhone has undergone a steady, gradual toxic chemical improvement in the last five years: the iPhone 2G received the worst overall score of all ranked phones, but the iPhone 4 and 5 are now among the top ten percent of phones.

Nice work. Cell phone manufacturers overall are reducing the amount of toxic chemicals used, and continue to make pledges to cut the worst offenders. See the image below for the overall reductions:

But now that the amount of chemicals is being reduced, the biggest problem is recycling. These devices can potentially leach toxic chemicals into the ground, so need to be removed from landfills and recycled or reused. Unfortunately only 8 percent of cell phones in the U.S. are recycled.

The iPhone 5 isn’t only making progress on green materials, it’s also one of the most energy efficient cell phones out there. It only costs $0.41 to charge an iPhone 5 for the entire year, according to a report from OPower. That’s a tiny amount of energy compared to laptops, desktops and TVs.

However, cell phone energy becomes a problem when you think about it in mass. The report says that “the collective annual electricity consumption of the iPhone 5’s sold within 12 months will be equivalent to the annual electricity usage of 54,000 US household.”

Related research and analysis from GigaOM Pro:
Subscriber content. Sign up for a free trial.

• Analyzing the wearable computing market
• Confused about the wireless markets? Here’s a breakdown
• Siri: Say hello to the coming “invisible interface”