In recent years there has been a significant paradigm shift in science, with the emergence of the endocrine disruption model. DES is now recognised as an endocrine disruptor, and the DES experience provides the primary model of endocrine disruption by environmental oestrogens.
The emergence of the Endocrine Disruptor Model
Environmental Oestrogens
During the 1980s, just as DES researchers were becoming aware of the widening range of DES-related effects, environmental scientists were trying to make sense of apparent chaos being seen in wildlife populations throughout the world. Across species and in all parts of the world, scientists were seeing wildlife populations under threat due to sterility, reproductive problems, aberrant development and behaviours.
It was hypothesised that a number of man-made chemicals released into the environment, although not oestrogens, act as oestrogens-mimics .For the past 70 years a large number of man-made chemicals have been released into the environment. These compounds are pervasive and persistent in the environment, and end up in our water supply as well as our food chain. Although not oestrogens, they act like oestrogens when absorbed by the body.
It was realised that many compounds introduced into the environment by human activity are capable of disrupting the endocrine system of animals, including fish, wildlife and humans. The consequences of such disruption can be profound because of the crucial role hormones play in controlling development.
What is an Endocrine Disruptor?
Put very simply, “chemical messengers” (hormones) are produced and released into the bloodstream by the various endocrine glands. These chemical messengers travel back and forth and they activate, regulate and control how the body develops and functions. The body’s three great integrating networks – the reproductive, immune and endocrine systems – are closely interconnected. Changes in one part of this complex system can have profound and totally unexpected consequences elsewhere because everything is so interconnected.
It used to be thought that this signalling was “infiltration proof”, with oestrogenic chemicals locking on to specific receptor cells, rather like a lock and key. DES is now recognised as an endocrine disruptor in that the body confuses DES with its own oestrogenic signalling messengers.
This results in epigenetic changes where DES exposure deregulates and changes the normal pattern of gene expression i.e. when genes are turned on and off. The epigenome is deregulated, with potential consequences being subsequent developmental disorders and disease manifesting over the course of a lifetime and trans-generationally.
The DES-exposed population has thus taken on added importance as leading indicators of the effects of endocrine disruptors: not all adverse effects of exposure are immediately apparent, but may expressed months, years, decades after exposure; the adverse effects are multiple and unexpected; and that the effects are trans-generational.