| Clean Air and Water (quality) | Clean Air and Water (quality) | 221 |
| Chemicals/Chemical Industry | Chemicals/Chemical Industry | 34 |
| Environment/Superfund | Environment/Superfund | 29 |
| Waste (hazardous/solid/interstate/nuclear) | Waste (hazardous/solid/interstate/nuclear) | 26 |
| Energy/Nuclear | Energy/Nuclear | 9 |
| Homeland Security | Homeland Security | 7 |
| Defense | Defense | 6 |
| Animals | Animals | 4 |
| Agriculture | Agriculture | 3 |
| Natural Resources | Natural Resources | 3 |
| Consumer Issues/Safety/Products | Consumer Issues/Safety/Products | 3 |
| Fuel/Gas/Oil | Fuel/Gas/Oil | 2 |
| Trade (domestic/foreign) | Trade (domestic/foreign) | 2 |
| Small Business | Small Business | 1 |
| Science/Technology | Science/Technology | 1 |
| Manufacturing | Manufacturing | 1 |