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What definition should be used for identifying EDCs?

There are different definitions under discussion, e.g. from the WHO/IPCS:

“An endocrine disruptor is an exogenous substance or mixture that alters function(s) of the endocrine system and consequently causes adverse health effects in an intact organism, or its progeny, or (sub) populations.”

Another one is from the Endocrine Society, the world leading society of endocrinologists:

“An endocrine disruptor is exogenous chemical or mixture that interferes with any aspect of hormone action.”

It is likely that the WHO/IPCS definition will serve as a basis for identifying EDCs in the EU, as referred to in several options of the EU Commission’s roadmap. The EU Endocrine Disruption expert advisory group considered, however, that the evidence of an endocrine mode of action and adverse effects “coupled with a biologically plausible relationship” should be sufficient to conclude on endocrine disruption.

We consider that the WHO/IPCS definition provides a useful scientific working definition.  However, for protective legislation this requires too high a bar of proof that a substance, by disruption of the endocrine system, “consequently causes adverse health effects”. This is because mechanisms of action can take years or decades to establish (if ever!), as exemplified by chemicals such as DDT or TBT. If regulation couldn’t happen until this complete data was available, then people and wildlife would have had many years of continued exposure to these chemicals. Therefore it is important to keep in mind that the legal text in the EU pesticides and biocides laws says “may cause adverse effects”.

This page is part of CHEM Trust’s Hormone Disrupting Chemicals FAQ – Full list of questions here.

This is the last question in the FAQ; the first question is “What are hormone disrupting chemicals (or endocrine disrupting chemicals, EDCs)?“.