Learning Resources

What are CECs?

Constituents of Emerging Concern (CECs) encompass any physical, chemical, biological, or radiological substance or matter in any environmental media that may pose a risk to human and/or ecological health, for which there is not currently published enforceable California or federal environmental or health standard, or the existing standard is evolving or being re-evaluated, and/or the presence, frequency of occurrence, source, fate and transport, and/or toxicology of which is not well understood, routinely monitored, and/or may lack analytical methods. CECs include a wide variety of constituents including per- and polyfluoroalkyl substances (PFAS), pharmaceuticals, personal care products (PCPs), flame retardants, disinfection by-products, certain urban pesticides, microplastics and nanomaterials, and numerous biological agents. CECs are increasingly being detected at low levels in surface water, and there is concern that these certain constituents have an impact on aquatic life (USEPA, 2021).

Where are CECs found in the environment?

CECs may originate from a wide range of point and non-point sources and may be found in groundwater, surface water, drinking water, soil, sediment, dust, air, food, and biota. Once released to the environment, there is often limited information regarding the transport and fate of CECs in the environment. Due to the environmental persistence of some CECs, failure to respond to CECs in a timely manner may result in long-lasting impacts to California’s water resources and require extensive costs to mitigate damages such as those posed by exposures that affect wildlife and human health.

What is being done in California?

California’s environmental authority is unified under the California Environmental Protection Agency (CalEPA). The State Water Resources Control Board (State Water Board) is one of six agencies that are tasked with various environmental oversight, and each agency has a role about managing CECs in California. The State Water Board implements CEC monitoring and management strategies for permitted discharges and receiving waters. Several regional water quality control boards (Regional Water Boards) have monitored and continue to monitor for CECs in wastewater effluent, stormwater runoff, and ambient water through pilot studies, Regional Monitoring Programs, and permit requirements. In addition, the State Water Board’s Division of Water Quality (DWQ), Division of Drinking Water (DDW), and Office of Information Management and Analysis (OIMA) have convened expert panels, funded research, and developed guidelines and regulations to monitor CECs in aquatic systems statewide. A CEC Program is currently in progress to develop a statewide CEC management strategy that will result in more coordinated efforts to address CECs in the environment.

The CEC Program is enhancing monitoring in California by combining traditional methods with next-generation tools such as non-targeted chemical analyses and bioanalytical assays. This integrated approach allows us to detect complex chemical mixtures, capture previously unmonitored contaminants, and better assess the risks of CECs in aquatic environments, strengthening our ability to protect water quality.

Bioanalytical Cell Assays (or In vitro Bioassays)

In vitro bioassays are rapid screening tools that assess the biological effects of chemicals by measuring activation or inhibition of key cellular pathways, such as nuclear receptor signaling. When used alongside chemical analyses, they capture the combined biological activity of all bioactive contaminants in a sample. These assays have been recommended to supplement environmental monitoring because they offer a practical, cost-effective approach to evaluating the risks of complex chemical mixtures while reducing time and animal use. Importantly, bioanalytical screening can detect a broader range of CECs, including unknown or unmeasured compounds that are not captured by targeted chemical analyses.

Non-targeted analysis (NTA)

Non-targeted analysis is a powerful technique that enables the detection and identification of chemicals in environmental samples without prior knowledge of their identity or properties. The major benefit of non-targeted analysis lies in its capability to identify unknown and unexpected chemicals, even at low concentrations. This information can inform the decision of whether to include additional target analysis in monitoring efforts.

For information on how other agencies are addressing Tire and Road Wear Particles, please refer to the links below.

• DTSC Safer Consumer Products – Motor Vehicle Tires Containing 6PPD
  Information on motor vehicle tires containing 6PPD, adopted as a priority product under California’s Safer Consumer Products program.
• CalRecycle – Tire Recycling and Market Development
  Resources on tire recycling, market development, and the Waste Tire Recycling Management Program, including the five-year plan.
• OEHHA – Health Effects of Recycled Waste Tires
  Evaluation of the health effects of recycled waste tires used in playground and track products.
• USEPA – 6PPD-Quinone
  U.S. Environmental Protection Agency’s page on 6PPD-quinone, including research and its environmental impacts.
• ITRC – 6PPD and 6PPD-Quinone Guidance
  Interstate Technology and Regulatory Council’s focus sheet and guidance document on 6PPD and 6PPD-quinone.
• SFEI – Microplastics from Tire Particles in San Francisco Bay
  San Francisco Estuary Institute’s research and fact sheet on microplastics from tire particles in San Francisco Bay.