According to the definition adopted by the Environmental Protection Agency in 1997:
Kavlock et al. (1996) published the EPA definition of an endocrine disruptor as: "an exogenous agent that interferes with the synthesis, secretion, transport, binding, action, or elimination of natural hormones in the body which are responsible for the maintenance or homeostasis, reproduction, development and or behaviour."
Consistent with this definition, the Agency has also stated that it "...does not consider endocrine disruption to be an adverse effect per se, but rather to be a mode or mechanism of action potentially leading to other outcomes, for example carcinogenic, reproductive, or developmental effects, routinely considered in reaching regulatory decisions. Evidence of endocrine disruption alone can influence priority setting for further testing and the assessment of the results of this testing could lead to regulatory action if adverse effects are shown to occur."
The current Agency position is consistent with a broad definition of endocrine disruption that must entail research questions. However, the EPA also recognizes that regulatory decision-making is generally based on adverse effects using legislatively mandated risk-based criteria.
In the EU, the regulatory definition of an endocrine disruptor in relation to potential threat to human health described within the Final Joint DE-UK position paper dated 13 May 2011 is: “An endocrine disrupter is an exogenous substance or mixture that alters function(s) of the endocrine system and consequently causes adverse effects in an intact organism, or its progeny, or (sub)populations.”
The EU definition embodies two key elements on which one can build criteria for identifying an endocrine disruptor of regulatory importance: adversity and intact organism observations.
With regard to adversity, it is proposed that the global and widely accepted definition produced by WHO/IPCS in 2004 is used to determine whether effects caused by exposure to a chemical are adverse:
“A change in morphology, physiology, growth, reproduction, development or lifespan of an organism which results in impairment of functional capacity or impairment of capacity to compensate for additional stress or increased susceptibility to the harmful effects of other environmental influences (WHO/IPCS 2004).”