The topics included in this guide a but a very few.
For a more extensive list (with links to more information about each topic) go to the EPA A-Z Topic Index. To give you an idea of the range of topics, here are the B's:
Beaches
Bed Bugs: Get Them Out and Keep Them Out
Benchmark Dose Tools
Biosolids
Bipartisan Infrastructure Law
Board of Scientific Counselors (BOSC)
Bristol Bay
Brownfields
Building the Capacity of Drinking Water Systems
Burn Wise