WILLISTON, Vt. -- A coalition of environmental groups said millions of obsolete computers that are ending up in landfills or incinerators have toxic materials that are a serious threat to the environment.

Stacked up outdated computers is a familiar sight in many offices and basements.

If such old computers end up in a landfill, they could contaminate the environment. Monitors are the worst offenders because the contain materials like lead and mercury.

That's why some activists want the makers of the machines held accountable.

There is a dizzying array of options for new computers, but when shopper Marc LeBlanc finally decides on one, he said he knows what he'll do with the old one.

"(I'll) donate it somewhere where someone will get benefits from it," LeBlanc said. "It's a good computer, I just want something a little faster with more opportunities."

LeBlanc could choose a place like Fred Wildt's store Used Computer Store.

The good computers are refurbished and resold at low prices, and some parts from the unusable ones are sent for recycling.

To cover costs Wildt charges a small drop off fee.

It's not unusual for shops or solid waste districts to charge a few dollars to take an old computer.

Recycling advocates don't have a problem with that, but said the costs of recycling are too often borne by taxpayer-funded programs or directly by consumers.

The new Computer Takeback Campaign calls for laws that hold manufacturers responsible and force them to take old computers back for free. That practice is required in some European countries where laws are tougher.

"A lot of these companies are multinationals, and they're already doing that at no cost to consumers in Europe," environmentalist Susanne Miller said. "Maybe that's something they should be able to do here in the us as well.

The Vermont Public Interest Research Group also wants the state to ban computers in landfills.

Only Massachuttes and California have similar laws now.