Constituents of Emerging Concern (CEC) Program

The Constituents of Emerging Concern (CEC) Program enhances California’s water resilience by balancing ecosystem needs with reliable local water supplies, reimagining how we monitor and manage contaminants to focus on prevention and proactive protection. By focusing on prevention and source control, this program aims to shift from reactive responses to proactive protection of public health, ecological health, and water quality. Using innovative monitoring tools and data-driven strategies, we address CECs holistically—targeting root causes and considering chemical, biological, and physical factors. When fully implemented, this systematic change in our approach to CECs will reduce contaminants in the environment while prioritizing transparency, collaboration, and stakeholder engagement to advance water resilience and ensure safer water for all Californians.

This webpage provides information about CECs, ongoing research, statewide data, and collaborative efforts to address these critical challenges.

Highlights & Quick Links

CEC Program - 6PPD-quinone Areas of Concern Map Published (July 28, 2025): The CEC Program's preliminary criteria map for 6PPD-quinone Areas of Concern in California, as featured in the December 2024 Informational Item on 6PPD, has been published to the State Water Board's Public GIS Portal.

6PPDq Areas of Concern - Preliminary Criteria - Overview
Water Boards – Informational Item on 6PPD and 6PPD-Quinone (December 4, 2024): Overview of the emerging contaminants 6PPD and 6PPD-quinone, their sources, environmental pathways, and toxic impacts on California’s freshwater ecosystems. This informational session included updates from the Water Boards’ Constituents of Emerging Concern Program, the Department of Toxic Substances Control (DTSC) Safer Consumer Products Program, and Caltrans, focusing on collaborative efforts to address these contaminants, regulatory updates, and monitoring strategies.

New Approaches for CEC Monitoring

We are increasingly confronted with complex scenarios in the aquatic environment involving numerous chemicals, their mixtures, and their transformation products. Most of these compounds are not detected through standard monitoring programs, and their associated health risks are not well characterized. To address these challenges, the CEC Program is building upon traditional approaches—such as targeted chemical analyses and toxicity tests—by expanding its analytical toolkit to better assess CEC issues in California. By incorporating next-generation monitoring approaches, such as non-targeted chemical analyses and bioanalytical cell assays, this effort will improve our ability to anticipate CEC-related challenges, substantially broaden the range of chemicals that can be routinely monitored, and evaluate substances that are data-poor or lack traditional toxicity information.

Learn More

Water Boards – PFAS Resources: Comprehensive information on per- and polyfluoroalkyl substances (PFAS), including statewide monitoring efforts, regulatory actions, research updates, and resources for water systems and stakeholders.

Water Boards’ Microplastics in Drinking Water
Information on microplastics in drinking water, including research, testing, and monitoring efforts.
CalRecycle
Plastic Pollution Prevention and SB 54 Implementation: Overview of the Plastic Pollution Prevention and Packaging Producer Responsibility Act (SB 54), including resources and updates on implementation.
Ocean Protection Council (OPC)
Plastics and Microplastics Resources: Comprehensive landing page on plastic pollution, featuring links to key resources like the Statewide Microplastics Strategy.

OPC Report – Microplastics from Cities to Oceans: Report analyzing the flow of microplastics from urban areas to the ocean, identifying sources and solutions.
Statewide Plastics Monitoring Plan & Strategy - San Francisco Estuary Institute’s project, funded by OPC, to develop a statewide plastics monitoring strategy.

SCCWRP Microplastics Tools and Data Repository - Southern California Coastal Water Research Project’s repository of tools, methods, and data for microplastics research and analysis.

Information Item on 6PPD and 6PPD-Quinone
The Water Boards’ Constituents of Emerging Concern Program, the Department of Toxic Substances Control (DTSC) Safer Consumer Products Program, and Caltrans presented an informational item on 6PPD and 6PPD-quinone on December 4, 2024. The presentation provided an overview of these CECs, including their sources, environmental pathways, toxic impacts on California’s freshwater ecosystems, and ongoing collaborative efforts related to regulation and monitoring.

Recording
Map of Areas of Concern for 6PPD-Quinone
To identify areas of potential concern where 6PPD-quinone may be present at concentrations above levels of concern in California, CEC Program staff developed a map that incorporates factors such as high traffic volumes, multi-lane arterial roadways, and stormwater discharge locations to indicate areas with a higher likelihood of 6PPD-quinone occurrence.

Access the Map