Topic Hubs™ are web-based guides to peer-reviewed pollution prevention information and expertise on a particular subject. They were developed by centers in the Pollution Prevention Resource Exchange (P2Rx) network, which was funded by U.S. EPA until 2018.

The Pollution Prevention Resource Exchange (P2Rx™) was a consortium of eight regional pollution prevention information centers, funded in part through grants from EPA. These centers provided pollution prevention information, networking opportunities and other services to States, local governments and technical assistance providers in their region. The centers represented a broad constituency, including state and local pollution prevention programs, manufacturing extension partnerships, cooperative extension and nonprofit organizations.

The Great Lakes Regional Pollution Prevention Roundtable (GLRPPR) served the U.S. EPA Region 5.