Current issues of concern

Endocrine Disrupters and Drinking Water

The endocrine system in humans controls the production and release of hormones within the body. There are many different hormones with different functions in the body, for example, hormones regulate growth, metabolism and sexual development and function. The major glands in the body involved in hormone control are the Hypothalamus, the Pituitary and the Thyroid glands.

There are many substances, both natural and synthetic which have the potential to mimic or interfere with the functioning of the human endocrine system. These are collectively known as Endocrine Disrupters (EDC’s) - a general, non scientific, term used to describe all kinds of substances thought to be able to act in this way. The “phenomenon” was first identified in the 1980’s as a consequence of observations of gender changes in fish in some rivers. Not surprisingly research into the phenomenon has led to concern that some of these substances could enter our drinking water supplies.

Research has shown that EDC’s are present in some of our rivers. However the amounts are exceptionally small and tend to occur only in immediate proximity to industrial and wastewater discharges. Many of these substances are unstable in river water and break down naturally and quite rapidly. This means that they are not detectable in the river water at the points where it is abstracted at the intakes to water treatment works. This has been demonstrated by research where sampling was done at locations specially chosen to represent the highest perceived, theortetical risk. European Commission funded studies have shown that conventional treatment of both sewage and water is very effective at removing EDC’s to levels below those that can be detected by the most sophisticated method of analysis currently available.

There is one one group of substances that attracts above average media attention, namely the components of the Birth control Pill (oestrogens), therefore, these have been studied in detail and we can now be very confident that that ordinary water treatment is effective at removing these substances. It is a popular media story to identify London’s water supply as being at particular risk, however, this ignores the fact that the major supplies to London are protected very well by large impounding reservoirs, where natural purification takes place during the 90 days storage.

It is not questioned that EDC’s can be a hazard to some wildlife and marine studies by Defra (EDMAR) have shown that there may be a significant effect on wildlife from these chemicals particularly under drought conditions. However these environmental concerns are quite separate from, and should not be related to, our drinking water supplies - unfortunately much that is written in the popular press does not make this important distinction between environmental and human health concerns.

In conclusion, it is correct that EDC’s are an environmental issue which continues to be researched with a view to the protection of wildlife. However, there is no evidence whatsoever that EDC’s are a potential risk to human health through our drinking water supplies. The Drinking Water Inspectorate continues to monitor the ongoing research in this field.