View SCCWRP’s full thematic Research Plan for Contaminants of Emerging Concern (PDF)
2025-2026 Executive Summary
Contaminants of emerging concern (CECs) refer to the thousands of chemical contaminants in aquatic environments for which evidence is emerging that they may pose a threat to ecosystem and human health. Introduced to water bodies through a wide array of human activities, CECs have the potential to impact the health of fish, other animals, and humans over time. Because these effects generally are not lethal or acute, California’s water-quality management community has historically struggled to manage these chemical contaminants and document their biological effects. SCCWRP is developing and applying next-generation strategies and tools for comprehensively monitoring emerging contaminants in aquatic environments. SCCWRP’s goal is to help water-quality managers efficiently and cost-effectively prioritize chemical classes that pose potential health risks to wildlife and humans.
SCCWRP’s CEC research is centered around building, testing, and refining tools for measuring chemical contaminants, including microplastics, in aquatic environments, and applying these tools to understand occurrence, fate, and effects of CECs. This CEC management paradigm is designed to help managers more cost-effectively and efficiently zero in on which of the tens of thousands of CECs in aquatic environments are potentially triggering adverse biological effects. SCCWRP’s research focuses on three main themes: (1) Development of exposure tools, including targeted and non-targeted chemical analysis to monitor unregulated chemicals and microplastics; (2) development of effects assessment tools to assess sublethal effects of CECs and to develop relevant bioindicators; and (3) characterization of environmental fate and transport of CECs to understand their physical, chemical, biological and ecological behavior controlling exposure levels and informing remediation strategies to mitigate their presence. The different data sets generated are then integrated to classify CECs and prioritize CECs of greatest concern.
This year, SCCWRP will develop a prioritization framework and populate it based on data collected over the past decade. SCCWRP will also continue developing and applying targeted analysis methods and sampling methods to identify and monitor CECs and other chemical stressors in water, sediment, and tissues. SCCWRP will continue supporting ongoing efforts to standardize microplastics collection and measurement methods, and to refine health-based thresholds for microplastics in aquatic environments. SCCWRP’s focus for 2025-2026 will be on:
- Risk-based prioritization of CECs in southern California watersheds: SCCWRP has spent the past decade generating exposure and effects data for a variety of CECs in freshwater and marine habitats. SCCWRP and member agencies partners will develop a risk-based prioritization framework based on exposure levels and toxicity thresholds, and develop a list of recommended monitoring actions for each risk category. SCCWRP will integrate existing data sets in the prioritization framework to identify those of greatest potential for negative effects. SCCWRP will continue to assess exposure and effects of new classes of CECs in water and sediments.
- Evaluating occurrence, levels, and environmental behavior of organic chemical stressors: SCCWRP is using previously developed sampling and measurement tools, developed by SCCWRP and its partners, to understand occurrence, fate, and transport of chemical contaminants. Accordingly, SCCWRP is using passive samplers to measure levels and fluxes of legacy persistent organic contaminants, as well as “DDT+” (i.e., DDT plus DDT breakdown products that are poorly understood), from sediments of the Southern California Bight at existing Superfund sites, at sites further offshore recently discovered to be heavily contaminated, and at oil platforms that could be decommissioned, to assess hazards that may be associated with exposure. SCCWRP is also assessing DDT+ contaminant levels in sport and commercial fish to understand and model exposure and bioaccumulation from such sites. Finally, SCCWRP is evaluating what CECs are likely present in urbanized southern California impervious surfaces (e.g., streets, parking lots) as a first step to understanding and prioritizing CEC monitoring in stormwater runoff.
- Investigating microplastics occurrence and effects: As the State Water Resources Control Board and California Ocean Protection Council develop statewide strategies for managing microplastics in aquatic systems, SCCWRP is building a scientific foundation for crafting informed management actions that optimally protect wildlife and humans from the health effects of microplastics exposure. To this end, SCCWRP is working at the national and international level to standardize methods for measuring microplastics in source water, sediments, and tissues. SCCWRP is developing standardized methods for collecting representative microplastics samples in these matrices, and refining risk-based approaches to refine microplastics toxicity thresholds.
