HP, Dell and Lenovo have been criticised for breaking promises to remove hazardous chemicals from their products.
Greenpeace's latest "Guide to Greener Electronics" list, which ranks the biggest technology companies on their green practices, shows that the world's biggest PC makers have all failed to improve their poor performance.
The three companies have backtracked on pledges to remove toxic materials such as PVC and brominated flame retardants (BFRs) from their products by the end of this year.
Apple is the only PC manufacturer that is phasing toxic substances out. Its new computer lines are virtually free of PVC and completely BFR-free. But the company was only 11th in the ranking because it has "unreasonably high threshold limits for BFRs and PVC in products that are allegedly PVC and BFR-free".
And while Dell, Lenovo and Acer have provided consumers with PVC and BFR-free alternatives, HP has not managed this.
Greenpeace International toxics campaigner Tom Dowdall said, "Greenpeace holds companies accountable for their promises. There are no excuses for backtracking, and no reason for these companies not to have PCs free of PVC and BFRs now."
While at current prices using alternative materials adds slightly to the cost of PCs, Dowdall said this would not be the case if companies bought in bulk and drove the price down.
PVC and BFRs do not just cause problems if they end up dumped on a Nigerian beach. Both contaminate humans and the environment throughout their lifecycle, and disposal is extremely environmentally damaging.
Greenpeace uses a list of measures to determine how environmentally friendly a technology company is, including how durable a product is, meaning less frequent replacement is required. It also looks at ease of recycling and use of toxic chemicals.
Nokia came top again, with a score of 7.4 out of 10. Samsung and Sony Ecrisson were second and third, followed by LGE, Toshiba and Motorola. Sony has dropped from 5th to 12th position as its performance has dropped, particularly on e-waste recycling. Dell, HP, Microsoft, Lenovo, Fujitsu and Nintendo make up the bottom of the table.