California's Adaptive Strategy for Monitoring Emerging Chemicals
Beneath the surface of California's vibrant waterways—from the mighty Sacramento River to the sprawling coastline of the Pacific Ocean—a complex chemical cocktail is silently accumulating.
These aren't the familiar pollutants of the industrial past, but a new generation of chemicals of emerging concern (CECs) that include everything from pharmaceuticals and pesticides to microplastics and synthetic compounds from everyday products.
What makes this threat particularly insidious is that these substances evade traditional water treatment and monitoring systems, entering our aquatic ecosystems in subtle yet persistent ways.
California has pioneered a revolutionary approach: an adaptive, comprehensive monitoring strategy that aims not just to identify today's chemical threats, but to anticipate tomorrow's.
Chemicals of Emerging Concern (CECs) encompass a vast array of synthetic or naturally occurring compounds that are not currently regulated, but which raise significant concerns about their potential impact on ecosystem and human health 7 .
These contaminants enter our waterways through multiple pathways, including municipal wastewater discharges, agricultural runoff, industrial effluent, and urban stormwater systems 3 .
The term "emerging" doesn't necessarily mean the chemicals are new—rather, that our ability to detect them has improved, or our understanding of their risks has evolved 8 .
The conventional approach to chemical regulation has typically been reactive—waiting until evidence of harm becomes overwhelming before implementing controls. This model is poorly suited to CECs for several compelling reasons:
Antibiotics, anticonvulsants
PBDEs, PFAS
PFOS, PFOA
Endocrine disrupters
Faced with these challenges, California convened a Scientific Advisory Panel to develop a more sophisticated monitoring strategy. The result was an iterative, phased framework that uses risk-based screening to prioritize chemicals for monitoring and management 2 5 .
This approach represents a significant advancement over previous methods that struggled to keep pace with the rapidly expanding list of potential contaminants.
The framework begins by identifying potential CECs through multiple information sources, including environmental occurrence data, toxicity studies, and changes in chemical use patterns 3 .
Through this rigorous screening process, the panel identified an initial list of 16 high-priority CECs that represent the most immediate concerns for California's aquatic environments 2 .
| CEC Category | Examples | Primary Sources | Risk Level |
|---|---|---|---|
| Pharmaceuticals & Personal Care Products | Antibiotics, anticonvulsants, cosmetics | Wastewater treatment plants | High |
| Flame Retardants | PBDEs, PFAS | Industrial discharges, consumer products | High |
| Pesticides & Biocides | PFOS, PFOA | Agricultural runoff, urban applications | Medium-High |
| Steroids & Endocrine Disrupters | Biogenic and synthetic hormones | Wastewater, agricultural runoff | Medium |
| Disinfection Byproducts | Chlorination byproducts | Water treatment facilities | Medium |
What makes this approach particularly innovative is its inherent adaptability. As the panel emphasized, the strategy must evolve with "the ever-changing nature of chemical use, technology, and management practices" 2 .
The process begins with comprehensive water sampling across diverse aquatic environments—marine waters, estuaries, and freshwater systems. Scientists collect samples from multiple matrices including water, sediment, and biological tissue 5 .
Once priority CECs are identified, the focus shifts to understanding their real-world effects. This phase incorporates bioanalytical screening methods that can detect biological responses to complex chemical mixtures 2 .
The final phase closes the loop by using collected data to refine future monitoring efforts. Monitoring results inform management actions commensurate with identified risks 2 .
| CEC Class | Water Column | Sediment | Biological Tissue |
|---|---|---|---|
| Pharmaceuticals | High | Low | Medium |
| Flame Retardants | Low | High | High |
| PFAS | High | Medium | High |
| Steroids/Hormones | Medium | Low | Medium |
| Microplastics | Variable | High | Medium |
Monitoring CECs in complex aquatic environments requires sophisticated analytical tools and specialized materials. The following details key components of the CEC researcher's toolkit, compiled from current monitoring methodologies 3 8 :
| Tool/Reagent | Function | Application in CEC Research |
|---|---|---|
| High-Resolution Accurate-Mass (HRAM) Mass Spectrometry | Enables identification of unknown compounds through precise mass measurement | Structural elucidation of previously unidentified CECs; non-targeted analysis |
| Solid-Phase Extraction (SPE) Cartridges | Concentrate and purify analytes from complex water samples | Sample preparation for trace-level CEC detection; reduces matrix interference |
| Liquid Chromatography Systems | Separate complex mixtures into individual components | Pre-separation prior to mass spectrometry analysis; improves compound identification |
| Metal-Organic Frameworks (MOFs) | Highly porous materials with tunable pore geometries | Selective capture and concentration of specific CEC classes like PFAS from water 1 |
| Bioanalytical Tools | Assess biological effects through in vitro assays | Screen for endocrine disruption, cytotoxicity, and other biological impacts |
| Passive Sampling Devices | Time-integrated sampling of water contaminants | Provide more representative contamination profiles than grab samples |
| Internal Standards | Correct for analytical variability during sample processing | Isotopically-labeled versions of target analytes for quantification accuracy |
| Quality Control Materials | Verify analytical method performance and reliability | Certified reference materials, method blanks, and matrix spikes |
The future of CEC monitoring lies in developing increasingly sophisticated detection methods that can keep pace with the expanding chemical landscape.
Moving beyond simply testing for predetermined chemicals, researchers are developing methods that use high-resolution mass spectrometry to identify any unknown compound present in a sample 8 .
Instead of solely measuring chemical concentrations, scientists are increasingly using cell-based bioassays that detect biological effects directly 2 .
The development of advanced sensor technologies promises to move CEC monitoring from discrete sampling campaigns to continuous, real-time assessment 8 .
As monitoring technologies advance, so too must the frameworks for interpreting and acting on the data they generate.
Researchers are developing models that can forecast the environmental fate and transport of future chemicals based on their structural properties 2 .
Inspired by the concept of a circular economy, this approach emphasizes designing chemicals and materials that are inherently safer and more sustainable 6 .
Effective CEC management requires coordination across multiple jurisdictions and sectors. California's model emphasizes stakeholder engagement and information sharing 5 .
California's adaptive framework for monitoring chemicals of emerging concern represents a fundamental shift in how we approach environmental chemical management.
By embracing iterative assessment, risk-based prioritization, and continuous refinement, this strategy offers a dynamic solution to the constantly evolving challenge of CEC contamination.
The value of this approach extends far beyond California's borders. As global chemical production continues to increase—with more than 4,200 plastic-related chemicals already identified as concerning 6 —the need for intelligent monitoring strategies has never been greater.
This adaptive framework represents a more humble and honest approach to environmental protection—one that acknowledges we don't have all the answers today, but establishes a systematic process for finding them tomorrow.