March 19, 2009
Q&A: EU Testing of Endocrine Disrupters
Since the 1962 publication of Silent Spring, there has been concern that chemicals in the environment could be harmful to both wildlife populations and human health.
The term “endocrine disrupter” was coined in 1991 by former Worldwide Fund for Nature (WWF) scientist Theo Colborn, who reported that some environmental chemicals can disrupt the body’s endocrine (hormone) system, and that effects of exposure during development can be permanent and severe.
Q: What does the term “endocrine disruption” mean?
A: “Endocrine disruption” refers to adverse effects on reproduction, development and/or health in general resulting from chemically-induced interactions with the body’s hormone system.
Q: What kinds of substances have been identified as suspected endocrine disrupters?
A: A range of synthetic as well as naturally occurring agents have been identified as potential “endocrine disrupters,” including synthetic hormones, pesticides, compounds used in the plastics industry and in consumer products, industrial by-products and pollutants, and even some naturally occurring substances in plants.
Q: What is the EU doing to address endocrine disrupter concerns?
A: Given the wide range of EU legislation under which pharmaceuticals, pesticides and other chemicals are regulated, the European Parliament in 1998 called on the Commission to examine the many research and regulatory questions related to endocrine disruption. The following year, the Commission published a proposed Community Strategy for Endocrine Disrupters [PDF].
In contrast to programmes under development in the United States and elsewhere, which reportedly aim to screen and test thousands of chemicals, the Commission strategy calls for a number of more moderate activities, including:
“Establishment of a priority list of substances for further evaluation of their role in endocrine disruption.” On the basis of independent reviews of the peer reviewed scientific literature, and in consultation with the Commission’s Scientific Committee on Toxicity, Ecotoxicity and the Environment, a candidate list [PDF] of 553 synthetic agents and 9 hormones was published in 2000, together with a series of actions proposed to further evaluate the role of these substances in endocrine disruption.
- “Use of legislative instruments,” such as “classification using existing test results for reproductive toxicity, carcinogenicity and danger to the environment.”
- “Establishment of monitoring programs to estimate exposure to and effects of the substances on the ED priority list.”
- “Identification of specific cases of consumer use for special action.”
- “Information exchange and international coordination.”
- “Communication to the public.”
Medium-term actions include “research and development” and “identification and assessment of endocrine disrupters.” In 2001, the Commission convened a European workshop on endocrine disrupters to address such topics as biomonitoring, research and development, testing methods and strategies, and international co-operation. Recommendations emerging from this workshop have helped to shape the EU’s research programme on endocrine disruption, which has received extensive funding under the 4th and 5th Research Framework Programmes. In addition, as members of the Organisation for Economic Co-operation and Development (OECD), the EU and many of its member states are de facto partners in the work of the OECD Task Force on Endocrine Disrupters Testing and Assessment, which is co-ordinating the international development of numerous animal and non-animal screening and testing methods.
The final, long-term goals of the Community Strategy are “legislative actions” to control substances exhibiting demonstrably harmful effects on humans, wildlife and/or the environment. To this end, endocrine disruptors have been classified under the REACH chemicals regulation as “substances of equivalent concern” to carcinogenic, mutagenic and reprotoxic (CMR) agents, which are subject to the most stringent requirements for authorisation or complete marketing bans. Similar provisions are expected to be introduced into EU pesticides and related legislation as it is revised.
Q: What tests are being developed to identify endocrine disrupting substances?
A: Screens under development to provide a rapid and inexpensive indication of a substance’s potential to interact with key hormone types (i.e., oestrogen, androgen and thyroid) include the following:
- Uterotrophic assay in rats and/or mice
- Hershberger assay in rats and/or mice
- Enhanced 28-day repeated-dose general toxicity test in rats
- Female and male pubertal assays in rats
- Intact male rat assay
- Amphibian metamorphosis assay
- Fish screen
- In vitro receptor-binding assays
- In vitro transcriptional/reporter gene activation assays
- In vitro steroidogenesis assay
- In vitro aromatase assay
Tests under development to provide definitive proof of harm to human and/or ecological health include the following:
- Enhanced 2-generation reproduction study in rats
- 2-generation reproduction study in birds
- 2-generation reproduction study in frogs
- Fish full life-cycle test
- Mysid shrimp full life-cycle test
Q: How many animals are used in these screens and tests?
A: The screening methods each consume between 20 and 60 animals (except for the in vitro methods, which do not consume any animals), while the reproduction tests each consume as many as 5,500 animals per chemical tested.
Q: Are animal tests accurate predictors of endocrine disrupting hazard to people?
A: Not necessarily. A 2003 white paper [PDF] commissioned by the US Environmental Protection Agency documented that chemical effects on the endocrine system can differ dramatically not only between animal species, but also between strains of the same species. This raises serious doubt concerning the human relevance of test results from rats or mice. Equally troubling are questions that have been raised as to whether the OECD validation of one or more animal tests has complied with the internationally agreed-upon standards.
Q: What is HSI Europe doing to help animals used in endocrine disrupter testing?
A: HSI Europe has been at the forefront of lobbying efforts to ensure that all available, validated non-animal methods and testing strategies achieve expeditious regulatory acceptance in the EU. Additionally, HSI Europe and affiliate organisations The Humane Society of the United States and Humane Society Legislative Fund have assumed a leading role in supporting implementation of the vision of “twenty-first century toxicology” articulated by the U.S. National Research Council, which would see animal tests that are decades old, costly, slow and of dubious relevance to people replaced by ultra-modern, efficient and human-relevant non-animal methods. HSI Europe is calling for a “big biology” project to meet this challenge, akin to the Human Genome Project of the 1990s, and are forging an international, multi-stakeholder consortium make this landmark vision a reality as quickly as possible.