PC manufacturers have still not figured out how to make a computer without PVC (polyvinyl chloride) insulation and toxic brominated flame retardants (BFRs), although some consumer electronics manufacturers are now able to produce smaller gadgets without those chemicals, Greenpeace reports in a new study.

Nokia has returned to the top of Greenpeace's ranking of consumer electronics manufacturers after a year away from the number one spot -- although not for any changes to its products. Instead, it scored an extra point for improving its systems for taking back unwanted electronics in India.

However, some of Nokia's products were praised for their energy efficiency, a new criterion Greenpeace added in the ninth edition of its Guide to Greener Electronics, released Tuesday.

Other companies singled out by the campaign group for excellence in energy efficiency were Apple, Sony Ericsson and Samsung.

Greenpeace monitors the materials used in electronics because of the health hazards they can pose on disposal. Some chemicals can pollute groundwater when they leach out of waste electronics dumped in landfill, while other chemicals are released into the atmosphere when waste is incinerated or broken up for recycling.

In this edition of its report, Greenpeace is most concerned about continued use of toxic flame retardants and PVC insulation: It noted that so far, no company has released a computer completely free of these materials, although some manufacturers are reducing the quantities used in their products.

Fujitsu-Siemens Computers jumped to number three in Greenpeace's rankings, up from 15th place, after it promised to eliminate PVC and BFRs from all its products by late 2010. Many other companies have set no such timetable.

The campaign group also praised Apple for saying its new iPod line will contain no PVC, BFRs or mercury, and that it will eliminate these materials from all of its products by the end of the year.

However, Greenpeace remained unhappy with other aspects of Apple's product design, including the way that the sealed casing makes battery replacement so expensive that customers are more likely to buy a new model than replace a worn-out battery.

Despite the clean white appearance of Nintendo's game console, the Wii, the company is still the black sheep in the Greenpeace rankings. On a scale from "Bad" to "Good", Greenpeace rated the company bad on most criteria, but only partially bad on its management of chemicals, its plans to phase out substances other than PVC and BFRs, its commitment to reducing greenhouse gas emissions and its disclosure of its own carbon footprint.