The most commonly accepted definition adopted at European level is the one given by the WHO in 2002: an endocrine disruptor is an exogenous (outside the body) substance or mixture that alters function(s) of the endocrine system (hormone production) and consequently causes adverse health effects in an intact organism, or its progeny, or (sub)populations.

Imbalances and dysfunctions of the endocrine system can lead to well-known diseases, such as diabetes and obesity, infertility and certain types of cancer. In addition, disruption of the endocrine system may cause birth defects and learning disabilities.

Endocrine disruptors can have a natural origin such as phytoestrogens in soya or an artificial origin, such as bisphenol A, certain phthalates, certain pesticides, etc.