Manufacturing a 24-kilogram (53-pound) desktop computer with its screen requires 10 times its weight in fossil fuels and chemicals, the study said. By way of comparison, a car or a refrigerator requires just twice its weight in natural resources.

The UN study found that manufacturing the computer and screen takes at least 240 kilograms (530 pounds) of fossil fuels, 22 kilograms (48 pounds) of chemicals and 1.5 tonnes of water -- totaling more than the weight of a rhinocerous or a car.

Microprocessors are a top culprit "because of their extremely light weight in relation to the enormous quantities of energy and chemicals needed for their manufacture," one of the study's authors, Ruediger Kuehr, told AFP.

Thirteen countries, most of them European, have already passed legislation anticipating computer recycling, said Eric Williams, co-author of the study, which recognized the efforts of Japan and Taiwan.

The federal government of the United States, the biggest producer and consumer of personal computers, has so far taken no steps to limit the environmental impact of the machines.

"The environmental consciousness is definitely lower in the United States," Williams said. He noted the tendency of President George W. Bush's administration not to favor regulation.

US sales of office computers increase annually by 10 percent while, worldwide, 130 million computers are sold each year.

"Most of the computers are made in the United States," Kuehr said.

"It is a matter of economics."

TERRA.WIRE