In recent years, the scientific community and regulatory bodies across the European Union have been grappling with a significant challenge: how to effectively identify endocrine-disrupting substances (EDS) while minimizing the reliance on animal testing. Endocrine disruptors, compounds that interfere with hormone systems, pose substantial risks to human health, wildlife, and ecosystems by contributing to conditions such as cancers, reproductive dysfunctions, and developmental disorders. Despite legislative frameworks permitting alternatives, animal testing remains the predominant approach for detecting these harmful chemicals, raising ethical concerns and efficiency bottlenecks.
A pioneering research initiative led by the DTU National Food Institute in Denmark has conducted a comprehensive evaluation of the current regulatory landscape governing endocrine disruptor identification within the EU and systematically mapped the application of New Approach Methodologies (NAMs). These alternative techniques—encompassing in vitro assays, in silico predictive modeling, and read-across strategies—offer the promise of reducing animal testing while maintaining stringent safety standards. However, the findings reveal that NAMs are still minimally implemented in regulatory practice, highlighting a critical disconnect between legislative provisions and real-world enforcement.
Central to the EU’s chemical regulatory framework is the premise that alternative tests can replace animal experiments if they demonstrate “similar predictive capacity.” Yet, according to Marie Louise Holmer, a leading expert from the DTU team, this criterion currently limits the acceptance of NAMs because only one method, read-across, is sufficiently mature for regulatory use. Read-across entails extrapolating toxicological data from well-characterized chemicals to structurally similar, less-studied substances. While this method accelerates assessment and reduces animal usage, its applicability is limited to substances with close chemical analogs. Other NAMs, such as high-throughput cell-based assays and computational toxicology models, remain under development and face validation hurdles.
The implications of widely adopting NAMs extend far beyond ethical considerations associated with animal welfare. Animal experimentation is time-consuming and resource-intensive, with the World Health Organization estimating that over 60,000 chemicals are currently in commercial circulation globally. Testing each compound for endocrine-disrupting potential using traditional methods would be prohibitively slow, spanning centuries at current rates. Therefore, integrating NAMs promises a paradigm shift, enabling faster, more cost-effective screening that could keep pace with the rapid introduction of new chemicals and better protect public health.
Endocrine disruptors interfere with hormone pathways that regulate myriad biological processes, including growth, metabolism, reproductive health, and immune function. Such disruptions can result in multifaceted adverse outcomes, including carcinogenesis and neurodevelopmental deficits. Currently, substances are regulated within the EU following confirmation of their endocrine-disrupting properties through methods predominantly reliant on animal testing. This reliance not only elicits ethical debates but also introduces variability and potential delays in chemical risk assessment.
Regulatory agencies and scientific researchers recognize the complexity involved in transitioning from animal-based methods to NAMs. The research team advocates for a balanced strategy that simultaneously advances the development and validation of new methods while optimizing existing animal tests to extract maximal informative value. It is vital that NAMs achieve or surpass the predictive reliability of animal models to ensure regulatory confidence, a goal that necessitates coordinated interdisciplinary efforts spanning toxicology, bioinformatics, and regulatory science.
Moreover, the study underscores the importance of fostering dialogue among all stakeholders involved in chemical safety regulation. This includes governmental agencies such as the Danish Environmental Protection Agency, European Union regulatory bodies, academic researchers, industry representatives, and non-governmental organizations. Building consensus on methodological benchmarks and establishing clear criteria for NAM acceptance will be essential to accelerate the integration of alternative testing methods into legislative frameworks.
The framework for identifying endocrine disruptors within the EU involves three essential criteria: firstly, the substance must exhibit harmful effects as evidenced by testing; secondly, it must be shown to interfere with endocrine (hormonal) systems; and thirdly, a causal link must be demonstrated between the endocrine disruption and the observed adverse effect. NAMs are currently utilized primarily to address the second criterion by evaluating hormonal system interference, but their application to demonstrating the resultant harm remains limited.
Innovative techniques encompassed in NAMs include in vitro assays, which utilize cultured cells or tissues to assess biotoxic effects at a cellular or molecular level without involving whole organisms. In silico models employ sophisticated computer algorithms and machine learning to predict chemical behaviors and toxicological profiles based on structural and physicochemical data. The read-across approach leverages existing data from chemically related substances to infer potential toxicity. Each method offers unique benefits and challenges that must be harmonized to form a comprehensive testing strategy.
Despite the potential of NAMs, significant scientific and technical obstacles must be overcome before they can fully replace animal testing in regulatory settings. These include the need for rigorous method validation, addressing uncertainties inherent in predictive models, and establishing standardized protocols accepted by regulatory authorities. Only through meticulous research, inter-agency cooperation, and stakeholder engagement can the promise of more humane, efficient, and accurate endocrine disruptor assessment become a reality.
The European Commission’s roadmap to phase out animal testing for chemical safety assessments marks an important policy initiative responding to public and scientific calls for modernization. However, as the DTU-led research confirms, the path to a fully animal-free testing paradigm will require sustained scientific innovation balanced with regulatory pragmatism. Until NAMs are proven to deliver equivalent or superior predictive accuracy, animal studies will remain indispensable, underscoring the necessity for their refinement and ethical optimization.
Overall, this research illuminates a critical juncture in chemical safety regulation—a transition period demanding collaborative solutions to harmonize ethical considerations with scientific rigor. Embracing NAMs offers an opportunity not only to improve animal welfare but also to enhance the speed and precision of toxicological evaluations in an increasingly chemical-saturated world. The urgent challenge is to bridge gaps between legislation, science, and practice to safeguard health and the environment effectively.
Subject of Research: Identification of endocrine-disrupting substances in the European Union and the integration of New Approach Methodologies (NAMs) as alternatives to animal testing.
Article Title: Assessment of endocrine disruptors in the European Union: Current regulatory framework, use of new approach methodologies (NAMs) and recommendations for improvements
News Publication Date: 12-Jul-2025
Web References:
- MERLON research project: https://merlon.dtu.dk/
- Original scientific article: https://www.sciencedirect.com/science/article/pii/S0273230025001138
References:
Marie Louise Holmer et al., “Assessment of endocrine disruptors in the European Union: Current regulatory framework, use of new approach methodologies (NAMs) and recommendations for improvements,” Regulatory Toxicology and Pharmacology, 2025.
Image Credits: DTU Food
