Endocrine-Disrupting Chemicals

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INTRODUCTION

An endocrine-disrupting chemical (EDC) is defined as: “an exogenous chemical, or mixture of chemicals, that can interfere with any aspect of hormone action”1. These can include natural or manufactured chemicals, such as pesticides, biocides, chemicals in plastic polymers (including breakdown products or constituents), food contact materials, cosmetics, and others. Common non-communicable diseases have been associated with environmentally-relevant doses of EDCs in human and animal populations, with differential exposure to EDCs emerging as a potential driver of observed health disparities based on race, ethnicity, and income. Research across different approaches and disciplines, including human, animal, and in vitro studies have unequivocally established causality between EDC exposure and effects and have often elucidated the endocrine mechanisms of action through which chemicals cause harm to humans, ecosystems, and biodiversity. Advances in scientific knowledge together with public interest prompted the design of policies to regulate the use of EDCs and prevent global health risks due to EDCs in the last decade.

As the world’s oldest and largest professional organization dedicated to the understanding of hormone systems and the care of patients with endocrine diseases, the Endocrine Society is committed to excellence in hormone science and incorporation of scientific knowledge into patient care and public health. Our members from over 120 countries are concerned about environmental chemical exposures and the role of EDCs in the etiology of diseases, particularly endocrine-related conditions. We strongly support the use of scientific knowledge in policies governing EDCs and other hazardous chemicals to improve public health.

Recognizing concerns about EDCs and their potential health effects, the Endocrine Society created a Task Force in 2008 to summarize scientific knowledge about EDCs. In 2009, the Task Force published the first Scientific Statement on EDCs, a landmark review of the science of EDCs, peer-reviewed and published in Endocrine Reviews. At the same time, the Society released the first position statement on EDCs, expressing its concern about the full translation of endocrine scientific knowledge into policies in the US. 

Because the science of EDCs has grown exponentially since 2009, the Endocrine Society published a second Scientific Statement on EDCs (EDC-2) in 2015, reviewing more than 1300 scientific articles published after the first Scientific Statement. Both Scientific Statements together establish a strong basis for concern about health risks associated with exposure to EDCs and provide a mechanistic understanding of how EDCs alter hormone actions, particularly during development, and at low doses. In this context, “low-dose” refers to concentrations of EDCs that are relevant to human exposure ranges, yet not typically evaluated in government-sanctioned or internationally-recognized testing strategies.

The scientific consensus in EDC-2 and subsequent research shows that:

• EDCs contribute to the burden of some chronic diseases and adverse health conditions, such as neurodevelopmental, reproductive and metabolic disorders, as well as some cancers, that have caused significant public health concern due to their increasing incidence.
• Non-linear and non-monotonic dose responses (NMDR) to EDCs are common and impair the assessment and management of risk when based on classical concepts of regulatory toxicology testing, such as potency, threshold, and the establishment of ‘safe’ doses of exposure.
• It is now well-established that the EDC effect depends upon when (i.e., at what life stage/s) the effect is assessed, with critical developmental periods of susceptibility, such as fetal development and infancy, influencing vulnerability to the effects of EDCs on later life outcomes.
• Regulatory hazard evaluation of EDCs is limited by the inability of standard good laboratory practice (GLP) toxicology testing and OECD/EU guideline studies to identify EDCs, as well as the omission of academic research, thereby leading to insufficient protection of public and environmental health with increased medical and other costs.
• New studies in humans have established associations between EDC exposures and numerous chronic diseases and adverse conditions, including mental health impacts. Furthermore, relationships between epidemiological studies and mechanistic experimental studies of cells and animals have greatly expanded during the last decade, identifying certain modes of action.

National and international regulatory agencies such as the Organization for Economic Cooperation and Development (OECD), European Chemicals Agency (ECHA), European Food Safety Agency (EFSA), United Nations Environment Programme (UNEP), World Health Organization (WHO), United States Food & Drug Administration (FDA), and the United States Environmental Protection Agency (EPA) have implemented programs to facilitate the translation of new scientific knowledge to governmental policies. However, there are serious deficiencies in these programs preventing the accurate identification of many EDCs and evaluation of their health risks. This has led to considerable concern that regulatory agencies will incorrectly assert “safety” of a compound or establish “safe” levels of exposure for compounds that cause harm. In many cases, regulatory determinations based on guideline studies, reflecting inadequate test strategies for critical human-relevant endpoints related to endocrine disruption, are inconsistent with peer-reviewed academic research, calling into question the rigor and effectiveness of regulatory approaches.

In 2017 the Endocrine Society established an Endocrine Disrupting Chemicals Advisory Group (EDC-AG) to improve the utilization of endocrine science in policies governing EDCs and help agencies address scientific and regulatory gaps, with oversight of member-led task forces operating in national, regional, and global policy environments. In 2024, the EDC-AG recommended the Society’s Position Statement on EDCs be updated to reflect new regulatory policies and proposals.

Read the full Position Statement