Endocrine disrupting chemicals interfere with hormonal communication between cells. Because hormones play a vital role in many processes, including organ development and function, mood and reproduction, endocrine disrupting chemicals could be having profound effects on our health. These substances are linked to reproductive abnormalities, immune disorders, obesity, cancer and other diseases. Endocrine disrupting chemicals are found in many everyday consumer products.
The endocrine system
The human body is made up from trillions of individual cells. Each cell is like a factory, constantly manufacturing the molecules which are ultimately responsible for all bodily functions, from temperature control to thought and rapid movement. This cellular manufacturing is what allows the body to stay healthy in response to an ever-changing environment, from inducing shivering when we get cold to absorbing excess sugar from the blood after eating.
In order to respond correctly to each change, cells in the body are constantly sending each other chemical messages to switch on and off these molecular manufacturing processes. Rapid responses, such as removing your hand from a hot object, are controlled by the nervous system. Larger events in life such as metabolism, mood, pregnancy and growth and development of organs are governed by the endocrine system: a set of glands which secrete hormones – the chemical messengers carried by the blood.
Transported at concentrations often as low as parts per trillion or less, hormones pass instructions to target cells where they initiate a complex cascade of changes to alter the molecules the target cell is manufacturing.
Endocrine glands include the thyroid gland, testes, and ovaries. Well-known hormones include oestrogen and testosterone, thyroxin and insulin. Because of the central role of hormones in the proper functioning of the body, disruption of the endocrine glands and hormone signalling can have a wide range of health effects from impaired mental development to increased risk of cancer.
Chemicals can interfere with endocrine signalling
An endocrine disrupting chemical (EDC) alters the normal functioning of the endocrine system in a way which may harm the health of humans or wildlife, by giving cells in the body the wrong messages or preventing correct messages from being sent or received.
There are many ways in which EDCs can upset hormone signalling, by interfering with the function of the parts of the brain which regulate hormone release, activating or blocking signalling cascades, interfering with how hormones break down or become deactivated, or by making it harder for the body to produce, transport or store hormones.
For example, some parabens and many UV-filters are endocrine disrupters because they can bind to and activate oestrogen receptors in target cells.
Certain phthalates are endocrine disruptors because they can block testosterone receptors, which can prevent processes essential for development of healthy reproductive organs in the male foetus from becoming activated.
It is not necessary for EDCs to be present in high concentrations for them to have a significant effect.