USEPA Includes Microplastics in Draft Contaminant Candidate List
Authored by: Mark Nishibayashi & Jon Rohrer, PG, CHg
The United States Environmental Protection Agency (USEPA) recently announced the draft Sixth Contaminant Candidate List (CCL6) for contaminants that do not have any current national drinking water regulations, but are known or anticipated to be found in drinking water. Being listed in the CCL may lead to future regulation under the Safe Drinking Water Act (SDWA) and/or inclusion in subsequent Unregulated Contaminant Monitoring Rule (UCMR) regulations. The new draft CCL6, published April 2, 2026, includes 75 chemicals, four chemical groups (microplastics, pharmaceuticals, per- and polyfluoroalkyl substances [PFAS], and disinfection byproducts [DBPs]), and nine microbes. The USEPA is seeking comments on the draft CCL6 to be received on or before June 1, 2026.
Of particular note is the addition of microplastics as a “chemical group” of interest/concern. Microplastics are listed with the qualification that additional research is needed before the USEPA can fully understand the associated health risks. Along with the draft CCL6 release, the USEPA and US Department of Health and Human Services (HHS) announced a $144 million initiative called the Systematic Targeting of Microplastics (STOMP), intended to build and standardize detection and measuring tools for microplastics.
The development of the analytical tools and methodologies for plastics will be important to monitor, as there has not been a consistent and/or agreed upon set of standards or protocols among scientists, let alone at the federal level, for monitoring microplastics or studying their effects on human health. Development of sampling and analysis methods for microplastics has proven challenging. For example, California has been working for the past several years to establish a microplastics testing and reporting program for drinking water sources; however, the rollout of the pilot monitoring program and subsequent phases of source water monitoring work have encountered significant delays, as it has taken years to develop the sample collection method.
The next UCMR (UCMR6) was sent by the USEPA to the Office of Management and Budget (OMB) in late March 2026 and is currently in review; nevertheless, the USEPA has received petitions from several states and interest groups to include microplastics in the forthcoming monitoring program. This seems unlikely given there are no federal analytical methods currently. It is unclear what this might mean for the UCMR6 cycle and whether a later revision to include additional analytes might be feasible.
Roux works with drinking water providers, industrial facilities, municipalities, and private sector clients seeking to understand and proactively manage microplastics-related risk. We’ve been closely monitoring microplastics science, policy, sampling, and analytical techniques. We can support clients with:
- Fate and transport assessments
- Sampling plan development
- Lab coordination
- Data interpretation
- Regulatory strategy
- Scientific literature interpretation
- Risk communication
If your organization is planning for future regulatory requirements that may result from CCL6—or simply needs clarity on where the science and policy landscape is heading—we are here to help. Please complete the brief form, and a member of our team will follow up to discuss your needs.
