The U.S. Environmental Protection Agency (EPA) recently published a prepublication draft Sixth Contaminant Candidate List (CCL 6). The CCL identifies contaminants not currently subject to national primary drinking water regulations that may warrant future regulation. In addition to various individual contaminants, the draft CCL 6 highlights four chemical groups: disinfection byproducts (DBPs), microplastics, per- and polyfluoroalkyl substances (PFAS) and pharmaceuticals — all known or anticipated to occur in public water systems.
Inclusion on the CCL does not mean a contaminant ultimately will be regulated, but it signals that the EPA views these contaminant groups as warranting closer scrutiny and that future monitoring obligations and drinking water standards are possible. Public water systems, manufacturers and other stakeholders should monitor the CCL 6 process closely, as listed contaminants may become subject to Unregulated Contaminant Monitoring Rule (UCMR) requirements and, eventually, national primary drinking water regulations.
Companies whose operations may contribute listed contaminants to drinking water sources should also be aware that public water systems seeking to comply with future regulations may look to potentially responsible parties to defray costs, as has occurred with PFAS.
The inclusion of microplastics in the draft CCL 6 marks an important development. The EPA plans to use the CCL 6 process to close significant data gaps before taking regulatory action. Specifically, the EPA plans to use the CCL process to develop a health-based definition of microplastics to identify which characteristics (e.g., polymers, shapes and sizes) are most associated with adverse health effects.
In addition, it will evaluate detection technology capable of reliably measuring microplastic concentrations and build a more complete picture of the sources of plastic pollution contributing to microplastics in drinking water.
The proposed PFAS group listing is also notable. The draft CCL 6 uses the same broad structural definition as CCL 5, covering a wide class of PFAS and excluding only those already subject to national primary drinking water regulations. This listing is consistent with the Agency’s broader PFAS regulatory agenda, which has expanded through drinking water standards, RCRA hazardous constituent listings and TSCA reporting requirements. The inclusion of a broad PFAS group signals that additional PFAS beyond those currently regulated may become candidates for future monitoring and enforceable standards.
The pharmaceuticals group encompasses all substances meeting the definition of “drug” under the Federal Food, Drug, and Cosmetic Act. The EPA has identified pharmaceuticals as a priority after more than a decade of public concern about their presence in drinking water sources.
The EPA is accepting public comments on the draft CCL 6 for 60 days following publication in the Federal Register. The Agency seeks input on the contaminants selected, data sources evaluated, screening and classification processes and the listing of each chemical group. Stakeholders with relevant data or perspectives should consider submitting comments.
For more information on the draft CCL 6 or its potential implications for your operations, contact Paul Beach, Dennis Donohue or a member of Warner's Resources, Energy and Environmental Law Practice Group.
