According to the US EPA’s Office of Inspector General (OIG), approximately 300 chemicals considered by the Resource Conservation and Recovery Act to be hazardous are unregulated. The Clean Water Act allows the EPA to regulate any substances, but the agency applies the rule to only 126 priority chemicals. Although industrial polluters are required to report discharge of hazardous waste to the EPA, the agency has not been enforcing the regulation consistently. Every five years, sewage-treatment plants must complete monitoring scans for the 126 priority pollutants. However, the EPA does not require all of them to be included on the Discharge Monitoring Reports of the plants. Among other recommendations by the OIG, the EPA has agreed to expand the list of chemicals it regulates and ensure compliance by sewage-treatment plants and their industrial users to the requirements of hazardous-waste notification. The EPA will complete the recommendations by September 30, 2015.

Source: US EPA