How Scientists Are Hunting What Our Eyes Can't See
Imagine walking through a modern city, surrounded by invisible chemical compounds. They're in the water we drink, the soil that grows our food, and the air we breathe. Over 350,000 chemicals are used in our society today, with more than 204 million substances registered in global databases 1 .
While most are harmless, some pose potential threats to ecosystems and human health. Traditional testing methods can only detect a few hundred of these compounds at best, leaving us largely in the dark about the complete chemical landscape around us.
The NORMAN network (Network of Reference Laboratories, Research Centres and Related Organisations for Monitoring of Emerging Environmental Substances) was established to enhance the exchange of information on emerging environmental substances. It brings together over 80 leading laboratories and authorities across Europe, North America, and Asia to tackle the challenge of identifying potentially harmful chemicals that conventional monitoring misses 1 .
How Non-Target Screening Works
Scientists look for specific, pre-defined chemicals using reference standards. This is like fishing for specific known fish species with specialized bait.
Researchers search for compounds they suspect might be present based on existing knowledge, without having reference standards on hand.
The true game-changer—scientists analyze samples without any preconceptions about what might be there, identifying entirely unknown substances.
Identifying unknown chemicals isn't a simple yes-or-no process—it's a spectrum of confidence that progresses through several levels 2 :
The gold standard, requiring a perfect match with a reference standard
Strong evidence from multiple sources but lacking reference standard confirmation
Plausible structure but with limited supporting evidence
Confident determination of the chemical formula but not the exact structure
The starting point, knowing only the molecular weight
Putting Non-Target Screening to the Test
In 2013, NORMAN organized a groundbreaking collaborative trial that marked a turning point for non-target screening. The network selected a single, well-defined water sample from the Joint Danube Survey 3—a comprehensive monitoring campaign along one of Europe's most iconic rivers—and distributed it to laboratories across Europe 3 .
This was the first exercise of its kind in environmental analysis, designed to answer a critical question: Could different laboratories using various NTS methods produce consistent and reliable results?
"The participating laboratories employed a range of techniques, though most experience within the NORMAN network involved water analysis of polar compounds using liquid chromatography coupled to high-resolution tandem mass spectrometry (LC-HRMS/MS)."
Participants tentatively identified roughly as many chemicals through suspect screening as through target methods, but very few via pure non-target approaches 4 .
Different laboratories using varied data sources and identification criteria produced inconsistent results, highlighting the need for standardized approaches 4 .
Participants used an incredibly wide variety of data sources during the trial, demonstrating that collaboration and data exchange were essential for progress 4 .
Data from the Frontlines
Antibiotics, antidepressants, painkillers
Very High DetectionForever chemicals like PFOA, PFOS, GenX
WidespreadHerbicides, insecticides, transformation products
High DetectionPlasticizers, flame retardants, surfactants
High DetectionInitial Launch
First centralized suspect list exchange
99 Lists, >100K Substances
Integration with major chemical databases
Regular Updates
FAIR data principles implementation
The NORMAN-SLE now serves as a specialized chemical information resource worldwide, with significant impact metrics including >40,000 unique views, >50,000 unique downloads, and 40 citations as of May 2022 4 .
Essential Resources for Chemical Identification
A centralized platform hosting multiple specialized databases for emerging substances, including the Suspect List Exchange, Substance Database, and Ecotoxicology database 5 .
The core analytical tools that provide the precise measurements needed to distinguish between thousands of compounds in complex environmental samples 2 .
A FAIR chemical information resource containing 99 separate suspect list collections from over 70 contributors worldwide, totaling over 100,000 unique substances 4 .
These tools represent a fundamental shift toward open science and collaboration in environmental chemistry, breaking down traditional barriers between research institutions and countries.
The Future of Environmental Monitoring
The development of harmonized non-target screening methods represents more than just a technical advancement—it signifies a transformation in how we understand and protect our chemical environment. The NORMAN guidance continues to evolve, recently extending beyond water analysis to include methods for sediment, soil, biota, dust, and air 2 .
This expansion reflects the growing recognition that chemical pollution affects all environmental compartments and requires comprehensive monitoring approaches.
"The journey from unawareness to comprehensive knowledge of our chemical environment is well underway. Through the pioneering work of the NORMAN network and the widespread adoption of non-target screening techniques, we are gradually illuminating the dark matter of environmental chemistry."
Machine learning algorithms are increasingly being employed to help prioritize chemicals of potential concern from the thousands detected in NTS.
Techniques for estimating concentrations without reference standards are improving, helping risk assessors determine which detected chemicals merit immediate attention.
The success of the NORMAN network has inspired similar initiatives worldwide, creating an increasingly connected global early warning system.
As instruments become more sensitive and software more sophisticated, the dream of near real-time comprehensive chemical monitoring is becoming increasingly attainable.
As research continues and these methods become more accessible, we move closer to the ideal of "one substance, one assessment"—a comprehensive understanding of each chemical's environmental presence and impact, anywhere in the world 4 .
In this endeavor, the combination of sophisticated technology, harmonized methods, and global scientific collaboration offers our best hope for managing the complex chemical landscape of the modern world.