A phone from Sony-Ericsson, a notebook from Sony and PCs from Dell and Hewlett Packard have come tops in a new study of environmentally friendly electronics devices, conducted by Greenpeace.

But there’s little cause for celebration, as "green" proved a relative concept in the "Searching for green electronics" survey. The three category-topping products only scored around half marks, leaving plenty of room for improvement.

Greenpeace published the list to demonstrate that some companies can develop products that do less harm to the environment, and to encourage others to do likewise. The group is particularly concerned about the dangers posed by the 20 million to 50 million tonnes of electronic waste it says we produce each year.

"We are building an Eiffel Tower of waste every 70 hours," said Zeina Al-Hajj, a spokeswoman for the group.

Worse, no-one knows what happens to most of that waste: more than 75 percent of it cannot be traced, according to the environmental lobby group.

"Is it in landfill, or being shipped to China, or sitting in attics? We really have no idea," she said.

Laden with toxic products including lead, beryllium, PVC, phthalates and brominated fire retardants, poor handling or storage of this waste can not only damage the environment but harm human health, the group warned.

To lower the risks, the group wants manufacturers to reduce the amount of waste from products. It also wants them to make any waste less toxic, by manufacturing products that use less energy, choosing environmentally friendly components and materials, and making them longer-lasting. Designing products that can easily be recycled would also be an improvement.

"Searching for green electronics" is a snapshot of products between August and November 2007. The group invited PC and phone manufacturers to provide information about their most environmentally friendly notebooks, desktop PCs, mobile phones, PDAs and game consoles. They then evaluated the products on four criteria: use of toxic chemicals, energy efficiency, recyclability and marketing.

Of the companies approached, 14 replied, providing information on 37 products. Some of those contacted, including Acer, Apple, Asus, Microsoft, Nintendo and Sharp, did not respond, or replied too late. This meant game consoles did not figure in the final report.

The highest-scoring device was Sony-Ericsson's T650i phone, with 5.30 out of 10. The other phones submitted scored between 3.6 and 4.4.

In the laptop category, the Sony Vaio TZ11 led with 5.29 points out of 10. Other products listed scored between 3.49 and 4.82.

Frontrunners in the desktop PCs category were the Dell Optiplex 755 and the Hewlett-Packard dc5750, with 4.71 points each.