California's Adaptive Strategy for Monitoring Chemicals of Emerging Concern in Aquatic Ecosystems
Imagine every time you shower, wash dishes, or take medication, you're potentially contributing to an invisible chemical cocktail flowing into California's rivers, lakes, and coastal waters.
This isn't science fiction—it's the reality of Chemicals of Emerging Concern (CECs) in our aquatic ecosystems. From pharmaceuticals and personal care products to flame retardants and pesticides, these substances enter water systems through wastewater treatment plants, stormwater runoff, and agricultural drainage, posing potential risks to aquatic life and human health 1 .
What makes CECs particularly challenging is their ever-changing nature—as soon as we understand one group of chemicals, new ones enter the market. In response to this dynamic threat, California has pioneered an innovative, adaptive monitoring strategy that represents a fundamental shift in how we protect our water resources 1 7 .
In 2014, California developed a revolutionary framework prioritizing chemicals based on potential harm rather than mere presence 1 .
A cyclical process that continuously incorporates new knowledge and adapts strategies accordingly 7 .
| Stage | Key Activities | Outcome |
|---|---|---|
| Assessment | Gather data on ecosystem and community needs | Understanding of system pressures and data gaps |
| Design | Develop clear goals, decision points, and monitoring plans | Strategic framework with built-in flexibility |
| Implementation | Execute real-world actions across the state | On-the-ground protection and data generation |
| Monitoring | Track ecological, social, and cultural indicators | Comprehensive dataset on changing conditions |
| Evaluation | Analyze results with scientists and communities | Understanding of what works and what doesn't |
| Adjustment | Revise strategies based on new knowledge | Improved approaches informed by experience |
"Imagine navigating a boat through fog. You don't just set a course and sail forward—you're constantly checking your compass, observing closely, and looking for signs that help you decide where to go next" 7 .
To understand how CEC monitoring works in practice, let's examine a comprehensive study conducted in the Malaga Mediterranean coastal area that directly compared multiple sampling approaches 6 .
Single-point water samples collected at 1-meter depth from 14 stations
Cage holders deployed for twelve months to develop microbial communities
HLB disks deployed for one month, continuously accumulating chemicals
| Sampling Method | Most Prevalent CECs Detected | Key Advantages | Key Limitations |
|---|---|---|---|
| Grab Water Sampling | Sun agents (0.391-0.495 ng/L), caffeine | Simple, provides immediate snapshot of water quality | May miss temporal variations and low-concentration compounds |
| Biofilm Mesocosms (Microfouling) | Sun agents, clotrimazole (~0.001 ng/L) | Concentrates contaminants over time, shows bioavailability | Long deployment time, complex analysis |
| Biofilm Mesocosms (Macrofouling) | Sun agents, caffeine | Represents accumulation in food web, longer-term record | Seasonal variability, species-dependent accumulation |
| Passive Sampling | Similar profile to macrofouling | Time-integrated data, concentrates trace-level contaminants | Requires calibration, may miss some compound types |
The spatial analysis of CECs along the coastline revealed that sun agents and caffeine represented the largest proportion of detected contaminants, ranging from 0.391 to 0.495 ng/L across sampling stations. Perhaps surprisingly, the timeline analysis over five consecutive weeks showed no clear upward or downward trend in CEC concentrations, suggesting relatively consistent input sources and persistence in the environment 6 .
Statistical comparisons between the methods revealed that passive sampling results most closely resembled those from macrofouling organisms, while significant differences existed between all approaches. This crucial finding underscores that the choice of sampling method fundamentally shapes our understanding of CEC contamination—different methods capture different aspects of a complex picture 6 .
The sophisticated science of detecting and analyzing CECs requires an equally sophisticated toolkit. Over years of development, researchers have refined a suite of methods to uncover these elusive contaminants in aquatic environments.
| Technique | Primary Function | Key Features | Real-World Application |
|---|---|---|---|
| High-Resolution Mass Spectrometry (HRMS) | Identification and quantification of CECs | Exceptional sensitivity and specificity; can detect unknown compounds through "suspect screening" | Identified 92 previously unknown compounds in the Venice Lagoon 4 |
| Passive Sampling Devices | Time-integrated sampling of waterborne contaminants | Accumulates chemicals over time; captures episodic pollution events; more efficient than repeated grab sampling | HLB disks used in Malaga study provided cumulative contamination data 6 |
| Bioanalytical Screening Tools | Assessment of biological effects | Measures cumulative impacts of chemical mixtures; links detection to potential effects | Cell-based assays can detect estrogenic activity even when individual chemicals are below detection limits 1 |
| Biofilm Mesocosms | Assessment of bioaccumulation potential | Shows which contaminants accumulate in living organisms; represents transfer through food webs | Twelve-month deployment in Malaga revealed differential accumulation patterns 6 |
| Nontargeted Analysis | Discovery of unknown contaminants | Identifies chemicals without prior knowledge of their presence; essential for keeping pace with new compounds | Enabled detection of 150 pharmaceutical ingredients in Venice Lagoon 4 |
Focused on known contaminants with established methods; limited scope for emerging compounds.
Development of methods for specific CEC classes; improved sensitivity but still limited to known compounds.
Using HRMS to screen for suspected compounds based on chemical databases; expanded detection capabilities.
Comprehensive analysis to identify completely unknown compounds; represents current state-of-the-art.
In 2020, the Science Advisory Panel reconvened to update its recommendations based on the latest scientific advances . This act of revisiting and revising previous guidance exemplifies the adaptive management approach in action—the recognition that environmental protection strategies must evolve alongside both the changing chemical landscape and our growing understanding of these contaminants.
The reconvened panel addressed critical new questions about which classes of CECs have the potential to adversely impact marine, estuarine, and freshwater wildlife, and how state management agencies can better address CECs through implementation of the risk prioritization framework .
Development of models that can forecast the input, fate, and effects of future chemicals before they become problematic 1 .
Moving beyond chemical-by-chemical analysis to assess cumulative impacts of chemical mixtures .
Continuous observation, evaluation, and adjustment of management approaches based on new knowledge 7 .
"In a time of rapid change, the most powerful thing we can do is stay open to new knowledge and to each other" 7 .
California's adaptive, comprehensive monitoring strategy for Chemicals of Emerging Concern represents a sophisticated acknowledgment that environmental protection in the 21st century requires both scientific excellence and organizational flexibility.
By embracing iterative learning, risk-based prioritization, and multiple lines of evidence, this approach offers a robust yet responsive framework for navigating the complex challenge of CECs.
As new chemicals continue to enter the market and our waterways, the adaptive management cycle of plan-act-monitor-evaluate-adjust ensures that California's protective measures will evolve in step with both the changing chemical landscape and our growing understanding of these contaminants.
"This approach ensures that protection strategies won't be a static document. It will be a living framework, designed to evolve with the coast and ocean it seeks to protect" 7 .
For other regions grappling with similar challenges, California's evolving strategy offers both a model and a mindset for protecting aquatic ecosystems in an era of rapid chemical innovation and environmental change.