A revolutionary scientific initiative is pioneering innovative methods to identify endocrine-disrupting chemicals and protect our health
Imagine a world where the very chemicals designed to make our lives easier—the plastic wrapping our food, the cosmetics we apply, the pesticides protecting our crops—silently interfere with our bodies' most delicate systems. This isn't science fiction; it's the reality of endocrine-disrupting chemicals (EDCs), and they're linked to rising rates of fertility problems, developmental disorders, and certain cancers. In this article, we explore how a revolutionary scientific initiative called the MERLON Project is pioneering innovative methods to identify these hidden threats and protect our health.
Faced with the staggering challenge of thousands of potential EDCs, scientists and regulators desperately needed a better approach to identify these hazardous substances 6 . The MERLON Project emerged as a comprehensive response to this challenge.
Launched in 2024, MERLON is a multinational, multidisciplinary research initiative funded by the European Union's Horizon Health programme. The project brings together world-leading experts from 12 partner institutions across eight European countries with a clear mission: to develop and improve tools to better identify and ultimately regulate harmful endocrine-disrupting chemicals 2 4 8 .
What sets MERLON apart is its specific focus on understanding how EDCs impact sexual development and reproductive function across critical life stages—from fetal development and "mini-puberty" during infancy through actual puberty and into sexual maturity 4 . By targeting these sensitive windows, researchers hope to identify how early exposures program later health outcomes.
| Aspect | Details |
|---|---|
| Full Name | MERLON (Mechanistically-based Research to Improve Identification of Endocrine Disruptors) |
| Duration | 2024-2028 8 |
| Partners | 12 institutions across 8 European countries 2 |
| Primary Focus | Effects of EDCs on reproductive health and sexual development 8 |
| Key Approach | Integration of new approach methodologies (NAMs) with traditional toxicology 4 |
| Regulatory Goal | Create a roadmap for improved EDC identification and regulation in the EU 4 |
Bringing together experts from various scientific fields
Focusing on critical developmental windows
Creating pathways for improved chemical regulation
One of the most groundbreaking studies supporting the MERLON approach comes from researchers at the Karolinska Institutet in Sweden, who developed a novel method for identifying endocrine-disrupting properties without traditional animal testing 3 . Their experiment showcases exactly the kind of innovative thinking that MERLON aims to expand upon.
The research team faced a significant challenge: conventional methods for identifying EDCs are slow, expensive, and rely heavily on animal studies. With tens of thousands of chemicals needing assessment, this pace is unacceptably slow for public health protection.
Using advanced molecular techniques to predict endocrine-disrupting potential
Researchers chose two suspected endocrine disruptors—cadmium and PCB-126—to evaluate their new methodology 3 .
Zebrafish embryos were exposed to these chemicals at critical early developmental stages. Zebrafish are ideal for such studies because they develop rapidly, are transparent (allowing easy observation), and share significant genetic similarity with humans 3 .
After exposure, the researchers used RNA-sequencing technology to analyze the transcriptomes of the zebrafish embryos. This advanced technique provides a comprehensive picture of which genes were turned on or off in response to chemical exposure 3 .
The gene expression data was then analyzed using a structured toxicological framework called Adverse Outcome Pathway (AOP) networks. AOPs are step-by-step maps that explain how a molecular disturbance can lead to adverse health effects at the organism level 3 .
The researchers employed both automated, data-driven approaches and manual, expert-driven methods to interpret their findings, allowing them to compare the effectiveness of these two interpretation strategies 3 .
The findings were significant on multiple levels. Both cadmium and PCB-126 were found to impact biological pathways related to hormone production and metabolism, confirming their endocrine-disrupting properties through multiple lines of evidence 3 .
| Aspect Studied | Finding | Significance |
|---|---|---|
| Cadmium Effects | Impacted pathways related to hormone production/metabolism 3 | Confirmed endocrine-disrupting properties through molecular evidence |
| PCB-126 Effects | Similarly disrupted endocrine-related pathways 3 | Validated method with another suspected EDC |
| Method Comparison | Both automated and manual data interpretation methods were effective 3 | Provides flexibility for future risk assessment applications |
| Regulatory Potential | Approach can support decisions on chemical safety 3 | Could accelerate the pace of chemical regulation |
| Animal Testing | Method significantly reduces need for traditional animal testing 3 | Represents more ethical and efficient testing paradigm |
The zebrafish experiment exemplifies a broader category of innovative testing strategies known as New Approach Methodologies (NAMs). These include advanced in vitro (test tube) methods, computational models, high-throughput screening, and other techniques that can evaluate chemical hazards more efficiently than traditional approaches while reducing animal testing 7 .
One of the most promising aspects of NAMs is high-throughput screening. This automated method uses microtiter plates—plates with dozens or even hundreds of tiny wells—to rapidly test thousands of chemicals for specific biological activity 7 . Robotic systems prepare the samples, expose cells or proteins to chemicals, and measure responses, generating massive amounts of data that would be impossible to collect manually.
Central to many NAMs is the Adverse Outcome Pathway (AOP) framework, which provides a structured way to connect molecular-level changes to adverse health effects 3 . An AOP is essentially a chain of events that begins when a chemical disrupts a biological system at the molecular level and describes how this initial disruption can cascade through cellular, tissue, and organ levels to ultimately cause disease 3 .
Molecular Event
Chemical binds to hormone receptorCellular Response
Altered gene expressionTissue Response
Tissue reorganizationOrgan Response
Organ dysfunctionAdverse Outcome
Reduced fertility| Method Category | Description | Application in EDC Research |
|---|---|---|
| High-Throughput Screening | Automated assays that rapidly test thousands of chemicals 7 | Identifying chemicals that interact with hormone receptors |
| Transcriptomics | Analysis of all gene expression changes in response to chemical exposure 3 | Detecting patterns of gene expression associated with endocrine disruption |
| Computational Toxicology | Computer models that predict chemical toxicity based on structure and properties 7 | Prioritizing chemicals for further testing based on suspected hazard |
| Adverse Outcome Pathways | Structured frameworks linking molecular initiation to adverse effects 3 | Providing mechanistic context for molecular changes observed in tests |
| In Vitro Systems | Cell-based assays that model biological processes outside living organisms 4 | Studying specific endocrine mechanisms without whole animals |
Modern EDC research relies on a sophisticated toolkit of reagents, models, and technologies. Here are some of the essential components used in cutting-edge endocrine disruptor research:
| Tool/Reagent | Function in EDC Research | Example Applications |
|---|---|---|
| Zebrafish Embryos | Vertebrate model with transparency and rapid development 3 | Studying developmental effects of EDCs; transcriptomics analysis |
| RNA-sequencing Reagents | Tools to analyze complete sets of RNA molecules in biological samples 3 | Identifying gene expression patterns changed by EDC exposure |
| Adverse Outcome Pathway Databases | Structured knowledge of toxicity pathways 3 | Interpreting molecular changes in context of potential adverse outcomes |
| High-Throughput Screening Platforms | Automated systems for rapid chemical bioactivity testing 7 | Screening large chemical libraries for endocrine activity |
| Computational Models | Algorithms predicting chemical-receptor interactions 7 | Estimating potential endocrine activity based on chemical structure |
| Cell-Based Reporter Assays | Engineered cells that signal when specific biological pathways are activated 7 | Detecting estrogenic or androgenic activity of test chemicals |
The work of the MERLON Project and similar initiatives represents a paradigm shift in how we approach chemical safety. By integrating multispecies molecular research, new approach methodologies, human clinical epidemiology, and systems biology, scientists are building a comprehensive understanding of how EDCs threaten human health 4 . This knowledge is already informing regulatory discussions in the European Union and beyond 9 .
For more extensive testing based on potential hazard
To existing endocrine-disrupting chemicals
That truly protect public health based on scientific evidence
While the science of endocrine disruption can seem daunting, initiatives like MERLON offer hope. They represent a coordinated, scientific approach to untangling the complex relationship between chemical exposures and human health. As these innovative methods continue to develop, we move closer to a world where we can identify hazardous chemicals before they cause widespread harm—creating a safer environment for generations to come.
The journey from scientific discovery to public health protection is long, but with projects like MERLON paving the way, we're developing the tools we need to address the invisible threat of endocrine disruption. As one MERLON researcher noted, the project aims to "create a comprehensive roadmap for advancing EDC identification, potentially transforming chemical safety assessment throughout Europe and beyond" 9 . In a world saturated with chemicals, this work has never been more urgent or more promising.