Endocrine disrupting compounds interrupt normal endocrine system function, in broad terms either by acting as a mimic to the normal hormone binding and stimulating a hormone response inappropriately or by binding to the normal receptor for the hormone and blocking normal stimulation of a response.
Endocrine-specific organs enable chemical communication between cells, including: thyroid glands, parathyroid glands, pancreas, testes, and ovaries. Along with many other cells that secrete hormones they make up what is known as the “diffuse endocrine system”. All organs and metabolic processes throughout the body are affected by hormone signalling and so the consequences of endocrine disruption can be complex.
Naturally occurring estrogens from plant sources, phytoestrogens, come directly into the diet from legumes such as soy and from orange juice, they are also ingested indirectly through milk. Long term exposure at low levels has been considered protective against some cancers as suggested by the low level of breast cancers seen in Japanese women eating diets high in soy.
Many industrial, agricultural and domestic processes produce chemicals that act as endocrine disruptors, for example waste incineration; cigarette smoke, car exhausts, paint and plastic production, manufacture of pesticides and fungicides. Pharmaceutical products, such as estrogens in the contraceptive pill, can contaminate water directly through recycling of waste water through water treatment plants. These compounds persist in the environment and result in their gradual increase in concentration in water courses.
The large numbers of compounds that act as EDCs, their persistence in the environment and the multitude of possible biological effects possible with disruption of normal hormonal function has led to concerns over their potential for detrimental environmental and health impacts and highlighted a need for monitoring. Endocrine disruption is thought to play a role in a range of issues in aquatic animals such as intersex, feminisation of fish and may also pose a broader risk to animal & human health including reduced fertility and increases in mastitis in livestock and developmentally abnormalities and increased cancer risks in humans.