(AP) U.S. technology companies lag foreign rivals in reducing hazardous materials in electronics and encouraging recycling, while American workers involved in recycling are exposed to too many toxins, an advocacy group says.

In its third annual report card, the Computer TakeBack Campaign assigned poor or failing grades to Hewlett-Packard Co., Micron Technology Inc. and Gateway Inc.

The study, published online Thursday after research by the Silicon Valley Toxics Coalition, accuses U.S. companies of being slow to reduce "e-waste," including lead, polyvinyl chloride and other hazardous materials used in computer manufacturing.

The new report came down especially hard on Texas-based Dell Computer Corp. for failing to send company representatives to shareholder meetings involving toxic materials policy. It also attacked the nation's top-selling computer manufacturer for dealing with a U.S. government contractor, UNICOR, which employs prison inmates to recycle outdated computers.

According to the Computer TakeBack Campaign, "high-tech chain gangs" are not guaranteed the safety protections needed to ensure protection against e-waste.

"The Dell position on e-waste is a stain on the soul of Dell - the company and its founder," the report states. "Michael Dell and his wife, Susan, make generous donations to children's health and environmental charities in the U.S., but ignore the health and environmental impacts of e-waste on children and adults."

Activists mocked Dell's use of inmate labor at a protest Thursday in Las Vegas, where company executives gathered for the Consumer Electronics Show.

Dell spokeswoman Michele Glaze defended the contract with UNICOR, which is paid by dozens of companies and government agencies to have federal inmates recycle electronics, wash laundry, make toner cartridges, stamp metal and perform other jobs.

Glaze said the lower wages earned by inmates allows Dell to recycle computers inexpensively. Owners of obsolete Dell machines pay shipping costs to return their computers but do not have to pay any additional costs.

"We are as concerned about this issue as the Computer TakeBack Campaign is," Glaze said. "We don't want people to throw away their computers."

Dell's failing grade mirrors lax environmental standards throughout the country, according to the computer take-back group.

Even the highest-ranking American company in the study, IBM Corp., "disappointed" researchers for selling American consumers computers containing brominated flame retardants, used to prevent fires in circuit boards. Some countries prohibit the flame retardants, which are suspected of blocking hormones and impairing some biological processes. In those countries, IBM ships machines free of the chemicals.

The Silicon Valley Toxics Coalition and another group reported last year that as much as 80 percent of electronic waste collected for recycling in the United States was shipped to Asia, mainly China, India and Pakistan - exposing migrant workers to several poisons - despite a 1994 convention banning the export of hazardous waste from rich to poor countries.

Environmentalists also worry that with the popularity of new liquid crystal display technology, which is sharper and more energy efficient than traditional cathode ray tube monitors, an increasing number of old monitors are ending up in the trash.

The National Safety Council estimates the United States will be awash in 500 million defunct computers and monitors by 2007. Only a handful of American computer makers, including Hewlett-Packard, Dell and IBM, take back old computer equipment for disposal with little or no cost to consumers. Thursday's report said less than 10 percent of outdated computer products will be refurbished or recycled.

The report applauded California and Massachusetts for banning the disposal of cathode ray tube monitors and TVs in landfills because of their lead content. Several states and municipalities are considering similar legislation.

The report also praised the European Union, which in October adopted directives that put the burden of recycling on the manufacturer.

Japan, home of the highest-ranking electronics manufacturers, Fujitsu and Canon, passed a law in 2001 requiring manufacturers to recycle certain parts. Japan also requires disclosure of chemical use in production plants.