Allied Waste Industries, Inc.

Allwaste, Inc.

American Ecology Corporation

Appliance Recycling Centers Of America, Inc.

Azcon Corporation

Berliner Stadtreinigungsbetriebe

Brambles Industries Limited

Browning-Ferris Industries, Inc.

Chemical Waste Management, Inc.

Clean Harbors, Inc.

Copart Inc.

E.On Ag

Ecology And Environment, Inc.

Industrial Services Of America, Inc.

Ionics, Incorporated

Iss A/S

Kelda Group Plc

MPW Industrial Services Group, Inc.

Newpark Resources, Inc.

Norcal Waste Systems, Inc.

Pennon Group Plc

Philip Environmental Inc.

Philip Services Corp.

Roto Rooter Corp.

Roto-Rooter, Inc.

Safety-Kleen Systems Inc.

Sevenson Environmental Services, Inc.

Severn Trent Plc

Shanks Group Plc

Shred-It Canada Corporation

Stericycle Inc.

Trc Companies, Inc.

Veit Companies

WMX Technologies Inc.

Waste Connections, Inc.

Waste Holdings, Inc.

Wheelabrator Technologies, Inc.

Windswept Environmental Group, Inc.