US Environmental Protection Agency (EPA) pages of interest:

• Enforcement and Compliance History Online (ECHO).  You can search for facilities with violations by ZIP code.
• Toxics Release Inventory (TRI). Again, you can search by ZIP.
• Superfund National Priorities List (NPL). Maps and details.

Note:  This does not replace ToxMap.  ToxMap was retired by the National Library of Medicine on Dec. 16, 2019.  No replacement is planned.  Citizens can no longer use that single search for on-site toxic chemical releases and hazardous waste sites from the EPA’s TRI Superfund NPL, as well as coal and nuclear emissions, Census demographics, Commerce income statistics, or health data from NIH’s NCI SEER program.